Optometric Case Analysis

Optometric
Case Analysis
MEDICAL RECORD DOCUMENTATION
The medical record is a medico legal document. The information

contained in the medical record is the property of the patient. Written
permission from the patient must be obtained before sharing
information with anyone. The physical medical record is the property of
the office where the examination was conducted.
Maintaining accurate and thorough patient records is essential for
providing optimal patient care. Proper medical record documentation is
necessary to record pertinent facts, findings and observations about an
individual’s health history, examinations, tests, treatments, and
outcomes. The medical record chronologically documents the care of the
patient and is and important element in contributing to high quality care.
The medical record facilitates:
The ability of the optometrist to evaluate and plan the patient’s
immediate treatment, and to monitor his/her health care over time
Communication and continuity of care among optometrists and other
health care professionals involved in the patient’s care;
Appropriate utilization review and quality of care evaluations; and
Collection of data the may be useful for research and education.
MEDICAL RECORD DOCUMENTATION
The medical record is confidential. If the patient requests a copy of

his/her medical record it must be provided to them. If the information is
for a third party (other physicians, school, insurance company, etc.), the
patient must complete a medical record release form. This form indicates
who is to receive the information and requires the patient’s signature in
order to be valid
The medical record is subject to subpoena. It is wise to avoid writing
comments that may prove someday to be embarrassing if not outright
damaging.
General Principles of Medical Record Documentation
The principles of documentation listed below are applicable to all types of

medical and surgical service in all settings.
. The medical record should be complete and legible. All entries should
be in ink – black or blue –only. Erasable ink should not be used.
. The documentation of each patient encounter should include:
Reason for the encounter and relevant history, physical examination findings
and prior diagnostic test results;
assessment, clinical impression or diagnosis;
plan for care; and
Date, and legible identity of the observer
If not documented, the rationale for ordering diagnostic and other ancillary
services should be easily inferred.
Past and present diagnoses should be accessible to the treating and /or
consulting physician.
Appropriate health risk factors should be identified.
The patient’s progress, response to and changes in treatment, and revision of
diagnoses should be documented.
The procedure and diagnostic codes reported should be supported by the
documentation in the medical record.
Any errors should be corrected using the “SLIDE” method. The “SLIDE” method
uses a Single Line through the error, Initial, Date and the correct Entry. Do NOT
obliterate or erase the error.
The SOAP Format
Identifying and Satisfying the Patient’s Needs

Good patient care can be described simply in these terms provided we extend
the concept of the patient’s needs to include the needs that the patient is aware
of and those that he/she is not. This is of particular concern with high-risk
patients. In order to accomplish this, the exam can be broken into four
components:
Subjective - the case history including CC, other ocular signs and symptoms,
previous oculars history, personal and family medical and ocular health history.
Objective – exam data and observation, all tests that may relate to history, tests
that identify high-risk situations and test that are required for baseline.
Assessment – diagnosis(es), refractive, sensorimotor/binocular and ocular health
Plan – treatment, patient education, and follow-up examination.
This is also referred to as the SOAP format of record keeping/analysis. All four
areas build from one to the other. The case history (S) should help to drive what
testing (O) is done and the assessment and plan (A/P) should explain all the
concerns of the patient noted in the case history or significant findings noted
during the examination.
The SOAP Format
When writing up the chart, the assessment and plan require some added
consideration. Each area should be broken down into subgroups. They are
generally ocular health, refractive and sensorimotor. Theses areas should be
prioritized based on importance to the overall case and documented in that
order. Therefore, the order that you see these subgroups will vary from chart to
chart. For example, a routine examination where the CC was only “distance
vision blur” and only a small increase in the distance prescription is found will
have “refractive” noted first. If during the same case you find that the IOP is
28mmHg in each eye, the first area noted would be “Ocular health” because that
is of more concern overall than a refractive change.
THE CASE HISTORY
The doctor may also learn more about the illness from the way the patient tells
the story than from the story itself – James B. Herrick 1861-1954
Clinical history taking is part art and part science. It allows for doctor-patient
interplay that when successful facilitates the remainder of the encounter as well
as subsequent therapy. Thus, the doctor should be doctor, actor, counselor,
therapist, educator, philosopher, and social worker.
Most clinicians consider the case history to be the most important “test” in the
entire examination. One mark of a good clinician is the ability to take a good
case history within an appropriate time frame.
“The Science of a Taking Case History”

There are several parts that should be included in each case history. They are:
. Chief Complaint (CC) The CC is a concise statement describing the symptom,
problem, condition, diagnosis or other factor that is the reason for the
encounter, usually stated in the patient’s words.
THE CASE HISTORY
. History of Present Illness (HPI) The HPI is a chronological description of the

development of the patient’s present illness from the first sign and/or symptom
or from the previous encounter to the present. It usually includes the following
elements:
 location
 quality
 severity
 duration
 onset
 frequency
 provocative factors
 modifying factors, and
 associated signs and symptoms.
THE CASE HISTORY
3. Review of Systems (ROS) ROS is an inventory of the body systems obtained

through a series of questions that seek to identify signs and/or symptoms which
the patient may be experiencing or has experienced in the past. This can be
accomplished verbally or through use of a questionnaire.
In a ROS, the following systems are recognized:
 Constitutional symptoms – fever, weight loss
 Eyes
 Ear, nose and throat
 Cardiovascular
 Respiratory
 Gastrointestinal
 Genitourinary
 Musculoskeletal
 Integumentary (skin and/or breast)
 Neurological
 Psychiatric
 Endocrine
 Hematologic/Lymphatic
 Allergic/Immunologic
THE CASE HISTORY
4. Past Family and/or Social History (PFSH) The PFSH consists of a review of
three areas.
Past history – the patient’s past experiences with illnesses, operations, injuries
and treatments.
Family history – a review of the medical events in the patient’s family, including
disease which may be hereditary or place the patient at risk; and
Social history – an age appropriate review of past and current activities.
During an optometric examination, the ocular history should include a thorough

exploration of the chief complaint and inquiry into other areas of visual
symptomatology. Most complete visual histories should explore these areas:
Clarity of vision - Blur at distance and/or near? With and /or without correction?
Type/Use of correction – Contact Lenses or spectacles, (If CLs, should include
questions about wearing habits, disinfect ion, etc. Is correction for distance or
near, or full time wear?
THE CASE HISTORY
• Headaches
• Eyestrain, asthenopia
• Flashes, floaters
• Diplopia
• Tearing, burning, itching, redness.
• History of trauma
• History of eye turn – self and family
• History of eye disease (i.e. Glaucoma, Macular Degeneration, blindness) - self
and family
• Visual Demands – work and hobbies. Remember to include working distances.
Any positive response should be explored thoroughly. When recording a history,

one must document any positive responses as well pertinent negative
responses.
THE CASE HISTORY
“The Art of Taking A Case History”

The case history, in many cases will set the tone for the examination. Therefore it
is important that one make a polite, professional first impression. When initially
greeting a patient, use their name and introduce yourself as Intern _____. Use
the correct title, i.e. Mr. Mrs. Or Ms., as appropriate. Introduce any other
individuals who may be present during parts of the examination (supervisors,
observing interns, or ancillary staff.) Explain the role of these individuals to the
patient.
In the exam room, be sure that the patient can sit comfortably (exam chair
height, position). Find a place for the patient to deposit any materials that they
have with them. To insure privacy during while taking the case history, the exam
room door may have to be closed.
During the history, there are many ways to non-verbally communicate interest.
Some of these are:
Sit at eye level with the patient. Make eye contact.
Sit at an appropriate distance (3-4 feet) open posture, no barriers.
No distractions
Appropriate voice
Appropriate use of hands and facial expressions, nod, touch (CAREFUL!)
LISTEN to your patient.
THE CASE HISTORY
Some Terms:
Symptom - something felt or noticed by a patient that can help to detect a
disease or disorder; evidence of a problem or disorder often but not limited to
subjective evidence
Sign – something seen by an examiner ; objective evidence of a problem or
disorder. Many signs go along with symptoms i.e. a rash or bumps are often seen
when patient complains of a rash
Syndrome – collective signs and symptoms characteristic of a particular disorder
or disease.
Problem – a sign or symptom presented by the patient.

Pertinent positive – the presence of a symptom or sign related to a specific
problem or diagnosis.
Pertinent negative – the absence of a sign or symptom that, if present, would be
suggestive of a diagnosis.
CASE DISPOSITION
As the case history is primarily for the doctor, the case disposition is primarily for
the patient. Once the examination has been completed, the case disposition
should be presented to the patient. Be sure that you have reviewed all items in
the history that were of concern to the patient and be prepared to discuss these.
The discussion should include:
• Both positive and negative results of your testing
• What is going to be done
• What the patient should expect from the “treatment”
• What is expected from the patient i.e. use of glasses, medical regimen
• When they are to return for care
• Ask the patient if they have any questions
• Tell the patient to contact you if they do have any questions at a later time
CASE DISPOSITION [CONT’D]
In the case disposition, the doctor must explain the diagnosis to the patient
relate it to the patient’s symptoms (or lack of symptoms), and discuss treatment
plans and prognosis. All of these must be clearly understood by the patient. If
glasses are to be prescribed, the patient must know when they are to be worn,
their role, limitations and future. The young myope should understand that the
myopia might increase; the presbyope should know that the need for stronger
prescriptions is influenced not by the new glasses but rather a physiological
change.
Occasionally, even after all best efforts, a patient may elect to decline treatment.
It can be as simple as holding off a prescription change to electing not to take
medications. Refusal of care is well within the patient’s rights. They must,
however, be counseled as to the outcome of the condition if it goes untreated. It
must also be clear that they understand what they have been told. These are
situations that require detailed medical record documentation including a
synopsis of the information that was given to the patient. Be careful to include
documentation that the patient verbally acknowledged that this information was
understood.
In the case disposition, the doctor must be careful not to promise more than can
be delivered. Symptoms that may be the result of multiple causative factors
don’t usually disappear if only one potential cause is eliminated.
The case disposition may be the essential ingredient in forming the patient’s
opinion of the doctor. Future visits and referrals are generated at this time.
CLINICAL DECISION MAKING
When you hear hoof beats in the woods, don’t think of zebras!
Every fact has an element of value, substantive and abstract, whose

interpretation is related to the nature of the person and to known disease
processes. Analysis suggests what the possible differential diagnosis(es) are and
what physical or laboratory tests are indicated. A treatment plan is outlined
including immediate and long-term prognoses. Progress notes are written
according to the patient’s response to the optical, pharmacological, surgical, or
orthoptic management. New observations derived from specialized diagnostic
techniques are added and consultation reports appended.
In patient care, when presented with symptoms a routine should be followed in
problem solving that considers high probabilities first for and eliminating each in
turn. There should be good reason, including eliminating the obvious before
subjecting the patient to elaborate more expensive investigations. This is basic
pattern of clinical decision making (CDM).
CLINICAL DECISION MAKING [CONT’D]
Data collection consists of historical information (patient and family), results

of testing, and information from other sources such as library and retrieval
systems.
CLINICAL DECISION MAKING [CONT’D]
In considering any diagnosis and treatment plan, the doctor must consider how
the condition and its treatment effects the patient. Clearly the patient should
benefit from the treatment of a condition. The rights as well as the needs of the
patient must be addressed. What is best for the patient must be more important
that the needs and wishes of the patient.
Data processing involves the clustering of data obtained from the history and
examination (includes laboratory analysis when needed). It is rare that a patient
will have a solitary symptom or sign of a disease. More commonly there will be
multiple symptoms and several related signs. It is the job of the clinician to fit as
many of these clues together into a meaningful pathophysiological relationship.
Other diagnostic strategies

Another diagnostic strategy that may be used is called “pattern recognition”. In
this situation, the doctors make the diagnosis simply by the recognition of a
constellation of observations, findings, etc. This is a skill that is difficult to learn
and can only be learned through clinical experience.
WRITING A SPECTACLE PRESCRIPTION
To avoid misunderstanding, the prescription is written in appropriate symbols. It must
be in ink, without errors. The prescription pad should be preprinted with the name
and the address of the optometrist(s) or practice. The telephone number should also
be included. The patient’s name and the date of the examination should be filled in.
The spherical component should be written first and should be followed by the
abbreviation “sph” if there is no cylindrical component. It is not necessary to add D or
Diopter. Three digits are specified. For example, it should be 2.00 not 2, and 0.25 not
¼. Do not omit the sign.
The cylinder is generally written in minus form but it can be written in plus form as
well. The symbol cyl is unnecessary and a times sign (X) serves for the axis. The
degree sign is omitted. Clinically, the combined with sign is not used to link the
spherical and cylindrical components.
If prism is to be included, specify clearly prism diopters and the direction of the base.
For oblique prism, add whether the base is up or down, in or out and specify the axis.
Prism can be incorporated into one lens or both – this should also be specified.
General specification may include base curve, material type (plastic, glass, high
index, photochromic, polycarbonate) coatings, or tints. For multifocals, specify type,
style, or size. Include near and far PD, and vertex distance in strong corrections.
The prescription must be signed by the optometrist (signature stamps are not
acceptable). Your state license number may be required on the prescription. This may
ether appear on the prescription pad, or be hand written or stamped onto each
sheet.
HYPEROPIA
Clinical Hyperopia is broader than it’s optical definition and often requires no
treatment. In low hyperopia, it maybe that unstable binocularity causes
symptoms. In absolute hyperopia, problems are compounded by decreased
visual acuity. In prescribing for hyperopia most clinicians will probably run
through a mental checklist of at least five factors: degree of refractive error,
available accommodation, and associated optical, binocular and pathologic
anomalies.
In low degrees of hyperopia, visual acuity may be good and symptoms absent. In
these cases treatment may consist of doing nothing gracefully. In higher degrees
of hyperopia, abnormal components should be looked for. Acuity may be
reduced especially as the patient gets older. Characteristic symptoms of
asthenopia can appear with close work at any age. A full or partial correction
may be ordered for distance or near use. When complaints are not specific, a
therapeutic trial is one alternative to doing nothing. A reading prescription is
occasionally indicated for those non-presbyopes whose nonspecific complaints
coincide with a recent change in occupation or avocation.
HYPEROPIA [CONT’D]
Therapeutic implications of available accommodation are self-evident in the

classification of hyperopia as latent or manifest. Latent hyperopia is made
manifest by relaxing ciliary tone through cycloplegics, fogging lenses, prolonged
occlusion or the natural course of aging. High latent hyperopia means excess
ciliary tone and is revealed by comparing cycloplegic and non-cycloplegic
findings. Its consequences are obvious in the accommodative strabismic but are
more subtle when symptoms are vague. Such cases might be evaluated by
comparing distance and near phoria, positive and negative relative
accommodation, and static and dynamic retinoscopy. Drug or disease induced
accommodative spasm is suggested by sudden onset, altered pupillary response,
increased esophoria, and large differences between cycloplegic and manifest
refractions. Higher ciliary tone is normal in infants and children.
The proportion of manifest hyperopia that can be overcome by available
accommodation is facultative; the residual hyperopia, which cannot be
compensated for, is absolute. Signs and symptoms will therefore depend on the
ratio of hyperopia to amplitude. The most common cause is presbyopia but any
drug or disease causing accommodative insufficiency will also have the same
effect, and treatment is directed at eliminating the underlying cause.
Most clinicians today aim at under correction of hyperopia. Donders suggested

that in cases where asthenopia was prominent and prescribing the result of the
manifest refraction did not cure the symptoms, one should correct all the
manifest and ¼ of the latent hyperopia. This technique of over correction
remains valid in convergent strabismus and pre-presbyopes.
Adult Hyperopia
For most adults between the ages of 20 and 40 with low to moderate hyperopia
who have not worn glasses before a prescription is indicated if the patient has
asthenopic symptoms. Visual acuity is rarely affected by this degree of
hyperopia. If the patient does have any loss of acuity, it is usually only at near or
is greater at near than at distance. The prescription given to this patient is for
use at near and can be the amount of plus found on routine noncycloplegic
refraction. The patient is advised to wear the lenses for near.
Partial prescriptions should be given to adult patients with clinically significant
latent hyperopia. Latent hyperopia is suspected when patients have amplitude
of accommodation less than expected for their age, when patients are esophoric
at distance through the refraction, when the result of the binocular balance
shows considerably more plus than the monocular subjective refraction, when
static retinoscopy shows considerable more plus than the subjective refraction,
or when the patient’s plus prescription does not reduce the near symptoms.
Common treatment strategy is the prescription of as much plus as possible
without blurring the patients distance vision and giving additional plus for near
in form of a bifocal if the patients’ symptoms so warrant. Patients who are given
partial prescriptions should be seen for follow-up 6-8 weeks after they begin
wearing their partial prescription and approximately every three months after
that until their refractive findings have stabilized and their symptoms have be
eliminated. As the patient’s accommodation begins to relax more plus will be
manifest on refraction and the prescription should be changed accordingly.
Patients need to be educated about wearing their lenses full time to reduce
accommodation and ultimately reduce the symptoms.
Patients with latent hyperopia are often reluctant to wear glasses because their
vision is often as good with the glasses as it is without. They are afraid that they
will become dependent on their glasses if they start to wear them. The
optometrist needs to anticipate these fears and remind the patient that glasses
can be prescribed for comfort as well as improvement in vision.
Pediatric Hyperopia
As with adults, decisions about prescriptions for children with hyperopia are largely
based on the child’s symptoms. The same principles can be applied but prevention of
amblyopia and strabismus must also be considered, particularly in children younger
than six years of age. One must also consider that few children younger than 6 can
articulate their visual needs or symptoms. Bilateral refractive amblyopia can occur in
persons with refractive errors lower than +2.50 DS. Unilateral refractive amblyopia
can occur in persons with as little as 1.00 D difference between the eyes.
Children at risk for development of refractive amblyopia should receive full correction
at an early age. The parents must be educated about the child’s need to wear the
glasses full time to ensure proper development of the child’s vision. Patients younger
than 6 should have follow-up examinations every three months to monitor visual
acuity and check on the patient compliance with full time wear of the glasses or until
maximal visual acuity and compliance are achieved. In children older than 6 visual
needs must be considered. Since school will increase the critical visual needs, a child
cannot/will not wear glasses that make the distance vision blurry. Often the full
correction found in noncycloplegic refraction is prescribed with additional plus at
near in the form of a bifocal if there is clinically significant esophoria, esotropia, or
latent hyperopia. When bifocals are necessary in younger children, an executive or
flat-top bifocal set at the mid pupil is recommended so that the child cannot avoid
using the segment. Older children who have mastered the art of bifocals can use
progressive addition lenses.
Cycloplegic Refraction
Cyloplegic examination is indicated in children when latent hyperopia is
suspected, when there is esophoria or esotropia, or when there is decreased
visual acuity that is not corrected with refraction. Young adults (16-40 yrs old)
should have cycloplegic examinations when there are complaints of headaches
or other nearpoint complaints but has little or no uncorrected hyperopia and no
other refractive or binocular vision anomaly. The need for a cycloplegic
refraction decreases markedly with age. Patients over 40 generally do not have
latent hyperopia that cannot be revealed by routine fogging procedures.
Choosing a cyloplegic agent should be based generally on the patient’s age. In
children under 6 complete cycloplegia can only be obtained by the use of
atropine. The adverse reactions and problems to consider, however, are that:
• Atropine must be instilled by the parent into the child’s eyes twice a day for
three days prior to examination
• Cycloplegia may last as long as two weeks
• The ointment is poisonous and may be cause death if taken by mouth
• A constant esotropia may result in a child with an intermittent esotropia or
high esophoria.
For these reasons, cyclopentolate is the agent of choice for the cycloplegic
refraction of children. Tropicamide provides an adequate amount of cycloplegia
in adults.
Cyclopentolate Tropicamide
Usual Dosage 1 drop of 1% solution 3 drops of 1%solution at
1 minute intervals
Time for maximum 25-35 minutes 20-30 minutes
onset of cycloplegic
effect
Duration of maximum 30-45 minutes Transient – may be no
cycloplegic effect more than 15 minutes
Duration of residual 6-24 hours 2-6 hours
cycloplegic effects
Possible adverse Hallucinations, ataxia, None reported in the
systemic side effects disorientation (occurred literature
only with the higher
than recommended
dosage) Use with
caution in children with
Down’s syndrome.
Associated binocular anomalies
Binocular motility problems in hyperopia are related to the accommodative-
convergence synkinesis. The required ciliary effort may produce esophoria out of
proportion to the compensating fusional vergences. The symptoms are similar to
those of accommodative insufficiency, and the hyperopia should be corrected.
Conversely, a hyperopic correction may induce exophoria, which may not be
tolerated. The patient now complains that the “glasses are too strong” though the
problem with the vision is oculomotor rather than ciliary. Exophoria is particularly
common in overplusing early presbyopes to postpone the need for reading glasses or
whenever a lowered acuity does not drive accommodation (convergence
insufficiency). Treatment consists of under correction (based on the AC/A), vision
therapy (to build up positive fusional ranges) or prisms. Additional illumination to
improve depth of focus may help tide the patient over this period of accommodative
insufficiency.
The need for full correction of hyperopia in accommodative esotropia should be
obvious but that rule is frequently ignored for fear that vision will blur. In fact a child’s
vision is seldom critical beyond three feet. The prescription must be strong enough to
neutralize the deviation to be of value. Insufficient correction may convert an
intermittent alternator to a constant esotrope. This can be very disconcerting to the
patient since the new glasses precipitated the change. In older children, bifocals may
be necessary to control the near deviation. Vision training may be used to enhance
binocularity. If these methods fail to control the deviation, surgery is indicated. Even
with adequate optical correction the esotropia may suddenly reappear and be related
to systemic illness, fatigue, or emotional stress.
Overcorrection at infinity
A useful tip for (especially) hyperopic lens corrections:
Occasionally a patient will complain that the new glasses blur the distance vision
especially at night. The patient may describe on coming headlights as
“feathered” or star-like”. They may also report seeing rings or halos around
lights. These symptoms are clues that there is overcorrection with plus. But how
did this happen after such a careful refraction?
SIMPLE! Refraction is normally performed with the distant acuity target 6m or 20

ft away. Therefore a precise refraction will correct a patient perfectly only for 20
ft away. For longer distances, the patient is actually overcorrected by +1/6 D.
This amount of error is usually negligible because the eye’s depth of focus is
sufficient to keep the retinal image sharp; but some hyperopes find the blur
intolerable, especially at night when the pupil is partially dilated, the eye is dark-
adapted and the depth of focus is reduced.
Solution: Instead of trying to guess which hyperopes may complain about

distance vision blur with their new glasses, some practitioners routinely reduce
the amount of plus they prescribe by 0.25D
MYOPIA
The primary sign of myopia is reduced distance visual acuity. There is a close
correlation between unaided visual acuity and the amount of myopia. It is
important to be sure that the amount of myopia measured in refraction is
consistent with the unaided distance visual acuity
MYOPIA [CONT’D]
Table from “Refractive Management Of Ametropia”, KE Brookman

MYOPIA [CONT’D]
Myopic Progression
Once myopia appears in childhood it generally increases (myopic progression)

until slowing or stopping in the middle to late teens. Myopia tends to progress at
a faster rate in cases where the onset was at an earlier age. Progression may
continue into young adulthood in selected populations, such as persons in
academic settings.
Although each case may have its own unique problems and challenges, there are
some general guidelines for correcting the myopic patient. In infants, it is
generally not necessary to correct myopia of less than 2.00-3.00 D. Myopia of
this amount may disappear by about age two. In preschool children, it is
appropriate to correct myopia of greater than 1.00-1.50 D since objects and
persons that they interact with are farther away than in infancy.
MYOPIA [CONT’D]
Since visual demands increase with each school year, the minimum amount of
myopia generally corrected decreases with age while attention is paid to any
possible development of near visual problems. In the first few years of school, it
may not be necessary to correct myopia less than 1.00D. In these cases, it may
be advisable to notify the child’s teacher about the visual problem. Follow-up
exams should be at six-month intervals since the myopia is expected to increase
over time.
Prescription Guidelines
Most clinician’s will give corrections for any of myopia necessary to improve the
visual acuity in adolescent and adult patients. Individual patients differ about
how critical they are about their distance vision. Prescriptions for as little as –
0.25 can be given in critical patients. In some cases, the patient is not sensitive
to small dioptric changes. In these cases low prescriptions are not warranted.
Finding the proper endpoint in the subjective refraction is important in these
patients. Many myopic patients mistake increased darkness of letters for
increased clarity. If the clinician is not careful with these patients, the
prescription will be for too much minus. When minus is increased in the
subjective refraction, the spherical endpoint has been passed if:
MYOPIA [CONT’D]
The patient says the previous lens was better

The change does not allow the patient to read any more letters on the chart or
The patient says the change makes the letters smaller and darker.
In cases where the patient is already wearing a correction for myopia, a change
in habitual correction should be made when a change in refractive error of 0.50
DS is found. Changes of less than 0.50 DS may have to be made in cases when
the patient is very critical about their acuity.
Correction for 0.50 DC should be included in myopic prescriptions since
uncorrected cylinder can be a cause of asthenopia. Patient sensitivity should also
be assessed in these cases.
Myopic patients entering presbyopia often find that they can read comfortably
without their glasses. This may be satisfactory if the patient has low myopia and
does not have any clinically significant amounts of astigmatism or
anisometropia. In cases of high myopia, significant cylinder or anisometropia,
bifocals or progressive addition lenses should be prescribed. Adaptation to these
types of lenses is easier when the powers are lower.
MYOPIA [CONT’D]
Associated Binocular Anomalies
Overcorrection of myopia will stimulate accommodation and therefore

reduce the amount of an exo deviation. For this reason, full time
correction of myopic patients with high exo deviation and normal
accommodation may be recommended. In cases of esophoria at near
(convergence excess) and in cases of accommodative insufficiency a near
point plus addition is recommended. In cases of esophoria at near a
useful way of determine an addition is to use just enough plus to make
the near phoria ortho or low exo. This can be done by using the AC/A
ratio or by performing near phoria testing through different amounts of
plus until the add that eliminates the esophoria is found.
MYOPIA [CONT’D]
Pseudomyopia
Some patients with emmetropia or low amounts of hyperopia have overactive
accommodation (accommodative excess) or difficulty relaxing accommodation
(accommodative spasm). This can result in pseudomyopia. Pseudomyopia occurs
most often in young adults who are doing a great deal of near work. The diagnosis of
pseudomyopia is confirmed when the subjective refraction is minus and the
cycloplegic is plano or low plus. The following symptoms/signs are suggestive of
pseudomyopia:
Asthenopia that is more severe than the test findings suggest
Intermittent distance blur
Reduced and variable distance visual acuity.
Low amplitude of accommodation for the patient’s age
Low PRA or high NRA or both
Fluctuations in retinoscopic findings, or subjective refraction
More minus on subjective than on static retinoscopy.
Minus lenses generally should not be prescribed for pseudomyopia. The goal of
treatment is to relax accommodation and eliminate the pseudomyopia. This can be
done with the prescription of any plus in the distance found in a cycloplegic
refraction, plus addition for near work, and/or VT to improve accommodation and
fusional vergences ranges. Patient education is crucial in these cases. Patients must
understand pseudomyopia, including the fact that distance vision may be blurry until
accommodation is relaxed.
MYOPIA [CONT’D]
Myopia Control
Some clinicians’ treatment regimens are designed to try to slow myopic
progression. This is referred to as myopia control. Some methods used to try to
slow myopic progression are undercorrection in the distance or part time use of
correction. Although these methods are commonly applied there is little data
published showing the efficacy of these methods.
Another method of myopia control is the use of bifocal lenses in prescriptions
for children. Published data on any slowing of myopic progression with bifocals
has mixed results. Some studies found no change in rate of progression with
bifocals while others reported reduced rates of progression. Several studies
showed a decrease in rate of myopic progression in myopic children with
nearpoint esophoria.
When you first recommend a bifocal to children and their parents, it may be
useful to demonstrate that the power of the lens needed for distance is not
equal to the power of the lens needed for clear, comfortable nearpoint use. (This
is usually the case in children with near point esophoria.) It can then be
explained that the way to incorporate two different powers into the same lens is
through use of a bifocal. Studies have shown that rates of myopic progression
are lower when the habitual nearpoint phoria is orthophoria or low exophoria.
This suggests that the optimal add is just enough plus to make the phoria ortho
or low exo at near.
MYOPIA [CONT’D]
Rigid gas permeable contact lenses have also been used for reducing the rate of
myopic progression. The reduced rate is most likely due to corneal flattening
from the contact lenses.
Vision therapy can be used to improve accommodative and convergence
function. Visual hygiene can also be employed to reduce some nearpoint stress.
The guidelines for visual hygiene are:
Take breaks from reading or near work about every 30 minutes. During these
breaks stand up, walk around, and look out a window.
Used a relaxed upright position when reading. Sit in a comfortable chair with a
straight back.
Use adequate illumination for reading. Avoid glare on the page by using a diffuse
light from a source directed over your shoulder from behind you.
Hold material at the proper working distance (Harmon distance). To find the
proper distance make a fist and hold it up against your nose. Your book should
be held at least as far away as your elbow.
Sit at least six feet away when watching TV.
Limit the time that is spent watching TV and playing video games each day.
Get some physical exercise each day.
While there is no direct evidence that these behaviors help in myopia control,
they appear to be good recommendations for reducing nearpoint visual stress.
ASTIGMATISM
“The study of medicine would be the ideal human pursuit if it were not for the
patients.” - Aesop
Astigmatism is the ametropia created by meridional variation in refractive

power. The typical astigmatic patient reports blurry vision at distance and near,
as well as asthenopic symptoms like headaches and eyestrain, brow aches, and
burning, irritated eyes. Patients who have with-the-rule and against-the-rule
astigmatism may benefit from squinting. The combination of lid pressure and
the pinhole effect will help to improve the visual acuity a small amount. Much of
the asthenopia is cause by prolonged squinting which leads to muscle fatigue.
Many times “the treatment is worse than the disease” since astigmats
experience spatial distortions with their glasses. Complaints of seeing flat
surfaces (such as walls and floors) as warped and vertical lines (telephone poles
and stop signs) as tilted are commonly associated with initial correction for
astigmatism. Although most patient eventually do adapt, it takes some patients
a long time to get used to their glasses.
ASTIGMATISM [CONT’D]
Prescription guidelines.
For young children, most practitioners will give the full correction. There is some
debate, however, about what age to write that prescription. Astigmatism
changes during the early years of life and probably reaches adult levels by 3 to 5
years of age. Because the early years are critical in terms of visual development,
high degrees of astigmatism should be corrected to allow normal visual
development and prevent meridional amblyopia, a form of refractive amblyopia.
For older children (age 10 through teens) whose vision has not been corrected
the full correction should be given. However, due to reduced plasticity and
increased visual demands, the patient may experience symptoms of spatial
distortion when first wearing the glasses. Careful patient and parent education
will help to facilitate adaptation.
With adult patients, the issues are quite different. There are cases where full
prescriptions are given and other cases where partial prescriptions are
necessary. Many practitioners give the full prescription as a first option. In these
cases, careful explanation of the spatial distortions that may be experienced
should be given. The patient must also understand that the adaptation period
may last a few days to a few weeks.
A more conservative approach is to give a full prescription to patients who have

symptoms with their old glasses and seem open to a prescription change. This is
especially the case when patients notice an improvement in the visual acuity
with a change in cylinder power or axis. It is also true in patients with laid-back
personalities who may adapt more easily to a new prescription.
In patients whose personalities are highly critical, anxious, or meticulous, a

partial prescription may be the best option. These patients are notorious for
having unsuccessful results with a full prescription because they are “driven
crazy” by the distortions. Patients who have a history of frequent changes in
their prescriptions or have a high amount of cylinder at oblique axes (which
causes a maximum of spatial distortions) respond better to a partial than to a
full prescription.
How do I modify the prescription?
There is, unfortunately, no pat answer to this question. In all cases, the proposed
prescription should be trial framed to see how sensitive the patient is to spatial
distortion. The decision to reduce the prescription to facilitate adaptation can
then be made. There are several acceptable options that can be used:
Reduce cylinder power and maintain the spherical equivalent.
Under prescribe the cylinder initially and then increase the cylinder power over
time.
Use the old cylinder axis and modify the cylinder power.
Move the axis toward 180 or 90.
Special Considerations
When the cylinder power is high it is wise to measure the cylinder axis at
distance and near. When the eyes converge to nearpoint, an excyclotorsion
occurs. With this excyclotorsion, the cylinder axes become misaligned with the
principle meridians of the eyes and the patient will report blur at near. Clinically,
a near cylindrical refraction is rarely done, but knowledge of this procedure may
help solve a patient problem that can’t be solved any other way.
To measure the change on cylinder axis and power at near:
Fog the left eye
Refract the right eye with the JCC for cylinder axis and power
Remove the fog from the left eye
Fog the right eye and repeat the refraction on the left eye.
A distance-to-near change in cylinder axis of greater than 5 or cylinder power

greater than 0.75DC may produce problems. The most effective solution would
be to prescribe separate distance and near prescriptions.
ANISOMETROPIA, ANISEIKONIA
Anisometropia can be broken into five categories:

 Simple hyperopic anisometropia – one eye is hyperopic and the other is
essentially emmetropic.
 Compound hyperopic anisometropia – both eyes are hyperopic.
 Simple myopic anisometropia – one eye is myopic, the other is emmetropic.
 Compound myopic anisometropia – both eyes are myopic.
 Antimetropia - one eye is myopic, the other is hyperopic.
The symptomatology of uncorrected anisometropia depends not only on the

amount but also on the type of anisometropia and how well the patient has
adapted. Hyperopes may have any of the elements of asthenopia like blurring
(from ciliary spasm), eye -ache, eyestrain, headache, avoidance or limited
tolerance for near work, and rarely (when fusion fails) diplopia. All these
symptoms tend to be associated with reading. Patients with myopic
anisometropia or antimetropia may complain of monocular blur. Some may
escape symptoms completely by alternating fixation.
ANISOMETROPIA, ANISEIKONIA [CONT’D]
Like the clinical symptoms, the clinical signs vary also. Patients may manifest
anisophoria, unequal accommodation, unequal corrected or uncorrected visual
acuities, tendency to close one eye or strabismus.
Management of Anisometropia
The first step in management of the anisometropic patient is to determine the
exact spectacle prescription and the best visual acuity in each eye. In patients
with unequal best-corrected visual acuity or with a difference in the perceived
image size between the two eyes, standard refractive balance techniques that
use patient comparisons of two ocular images to equalize the stimulus to
accommodation often do not work. In cases like this, accurate objective
measurements can be made with a cycloplegic refraction. Normal fusion will not
be achieved in patients with anisometropia unless the correct refractive balance
is in place.
Clinically, the prescription that incorporates the exact balance is not always
tolerated. Patients with large amounts of anisometropia reject an initial
prescription that includes the full balance found in a cycloplegic refraction. The
eventual goal is to prescribe the full balance so progressive adaptation to the
balance must be made.
Careful testing and evaluation of strabismus and amblyopia should be made in
patients with anisometropia. These cases should be managed based on results
of all testing and patient’s clinical history.
Aniseikonia
Aniseikonia is the condition in which there is a difference in the size or shape of the
images presented by the eyes to the visual cortex. More simply stated, it occurs when
a patient perceives an image size difference between the two eyes. In a clinical
setting, aniseikonia is most often encountered in the treatment of patients with large
amounts of anisometropia although aniseikonia may also result from differences in
spatial density of the photoreceptor elements.
Anisometropia can be classified as either refractive or axial in origin. In refractive
anisometropia, the refractive surfaces of the optical components between the two
eyes are different. An example of this is the patient who is unilaterally aphakic. If the
anisometropia is completely axial and the corrective spectacle lens was placed at the
anterior focal plane of the eye, the size of the retinal images would be identical in
eyes with the same refractive power (same corneal and lens configuration). This
principle is Knapp’s Rule. It suggests that if you know positively that the
anisometropia is due only to a difference in the axial length of the two eyes, you
should not have to worry about correcting for aniseikonia. When this law is applied,
patients with axial anisometropia and aniseikonia would be prescribed spectacles and
patients with refractive anisometropia and aniseikonia would be prescribed contact
lenses. Although, as a clinician you should keep Knapp’s rule in mind, there are many
too many exceptions for this to be used as a hard and fast clinical rule. Many
clinicians try contact lenses first in the management of patients with anisometropia.
This is not only preferable for cosmetic reasons but also reduces or eliminates the
aniseikonic symptoms.
The device of choice to measure the amount of aniseikonia has long

been the AO Office-Model Space Eikonometer. It is no longer
manufactured and therefore is not readily available in most optometric
practices. As a practical substitute, an iseikonic trial lens set can be
used. These lenses (often referred to as size lenses) are manufactured to
produce varying amounts of magnification (1%, 2%, etc.) and have no
dioptric power. When they are placed over a patient’s prescription, you
can determine the amount of aniseikonia by means of equalizing the
perceived image sizes between the two eyes. Iseikonic lenses can be
used as a clip-on to determine if a patient’s symptoms are relieved by
correction of the aniseikonia. These results can then be used to design
or modify a spectacle prescription to eliminate the aniseikonia.
If you do not have an instrument to measure the aniseikonia, you can
use a quick rule of thumb to predict the aniseikonia. For every diopter of
anisometropia, presume a 1% difference in the perceived image size
between the two eyes. Most patients can accept a 2-3% difference in
retinal image size but remember that there are large individual
variations in sensitivity.
Binocular Vision
Patients with spectacle-corrected anisometropia often demonstrate
varying amounts of heterophoria when tested in different directions of
gaze. This is caused by variations in the prismatic effect caused by the
spectacle lenses. This is referred to as optical anisophoria. Optical
anisophoria can produce the same asthenopic symptoms as “regular”
heterophorias and can even lead to diplopia when the prismatic effect is
too great and fusion is disrupted.
Meridional Aniseikonia
Meridional aniseikonia is rare but can occur when the cylindrical
correction differs by more then 1.00DC in the corresponding meridians.
The induced magnification difference can produce stereoscopic
distortion that can cause the patient to become symptomatic.
Fortunately, many of these disturbing effect are minimized by
adaptation and the use of appropriate spectacle lens designs (i.e. use of
minus cylinders, minimize the vertex distance, and accurate placement
of the optical centers, index of refraction of lens material).
PRESBYOPIA
“No wise man ever wished to be younger” –Jonathan Swift
or
“Old age ain’t no place for sissies.” – Bette Davis
Contrary to popular opinion, age alone is not a reliable guide to the onset of
presbyopia., which may begin as early as 36 or as late as 50 and still be normal
for a given patient. The onset of presbyopia depends on both the amplitude of
accommodation, which can be measured clinically, and the patient’s demand for
accommodation, which can be assessed by a careful case history.
Patients with presbyopia typically complain of blurry vision at near or other
ocular discomfort and fatigue after fairly brief periods of near work. Many
patient’s literally complain that their “arms are too short”. This occurs due to an
instinctive attempt to compensate for the decline in the ability to produce plus
power by holding material farther away. After reaching physical limits, these
patients will seek professional help. Clinical point: Many early presbyopes not
only experience blur for near tasks, they also have difficulty ‘unfocusing’ when
they look up from reading. Their distance vision may remain blurry for seconds
to minutes. These patients may present with a complaint of blurred distance
vision. This inability to relax the accommodation quickly is as much a symptom
of the loss of lens elasticity as is the loss of accommodative amplitude. A
thorough case history will elicit the link between near work and distance vision
blur.
PRESBYOPIA [CONT’D]
Common exam findings associated with presbyopia are

 Decreasing amplitude of accommodation, usually below 5.00D
 Increasing lag of accommodation, requiring increased plus (or decreased
minus) at near for normal visual acuity.
 Increasing exophoria (or decreasing esophoria) at near, although some
patients with high AC/A ratios manifest esophoria in early presbyopia.
 Decreasing PRA
 Absence of a blur finding in base-in and base- out vergences measurements at
near

Prescription Considerations and Guidelines
No reading add should be ordered without a specific complaint. Since
overplusing is probably the most common error in prescribing, the rule to
prescribe the weakest add is a good one.
The distance at which a patient works is referred to as the customary near
working distance (CNWD). The total need for plus power at near depends on the
distance between the patient’s eye and the object of regard. Optometrist
assumes that the average patient views things from a distance of 40 cm, which
would require a total of +2.50D of plus power derived from the sum of
accommodation and the plus add of a prescription. Several things can affect
CNWD:
Customary near tasks
Vocational and avocational considerations
The patient’s stature
Patient’s ametropia and lens effectivity
In deciding how much plus to prescribe, the clinician must consider the patient’s
near visual acuity and the entire range of near distances over which the patient
works. In general, the add should place the patient’s CNWD at the dioptric
midpoint of the range of clear vision. An add that requires a patient to use
exactly half of his or her amplitude of accommodation will achieve this goal.
When the add provides good vision and a good range of clear vision the patient
will be able to function well with the add. Checking the visual acuity and range
of clear vision through the proposed near add are the final, definitive tests to
determine if the add is correct. All other means of determining the add should
be checked against the outcome of vision and range.
Many persons with advanced presbyopia experience intermediate blur. There is
a range of distances too far to be seen clearly through the add and too close to
be seen through the distance because the amplitude of accommodation is too
low. The likelihood that a patient will experience intermediate blur increase with
the power of the add. Intermediate blur occurs when the add exceeds the
amplitude. If intermediate blur is unacceptable based on patient demand, the
patient may need separate prescriptions, a trifocal or a progressive addition lens
(PAL).
A “normal” add varies with the age of the patient (see attached tables). Adds
between +0.50 and +3.00 are very effective for the vast majority of patients. A
variety of diseases and medications may influence the patient’s amplitude of
accommodation. Any pathologic condition that results in permanent damage to
the parasympathetic axons of the oculomotor nerve or the post-ganglionic fibers
leads to a reduction in the amplitude of accommodation. Anticholinergics may
partially or totally block the neuromuscular junction at the ciliary body, reducing
the amplitude of accommodation. If a patient has a lower than expected
amplitude of accommodation, all relevant diseases or medications must be
considered.
Binocular Vision
Whenever a patient looks through an add at near, accommodation will be less
than without the add for the same viewing distance. Because of the resulting
relaxation of accommodative convergence, the patient’s phoria will shift in a
more exo direction. Patients with advanced presbyopia may have high
exophoria at near. In most cases, these patients are not symptomatic. However,
some patients may experience fusional stress due to the increased exo posture.
Because they cannot give up the add without sacrificing clear near vision, these
patient need both the add and vision therapy, or base-in prism, for their
convergence insufficiency.
Psychological Issues
Many patients fall victim to the “youth culture” of today. They correctly
recognize that the need for reading glasses occurs with advancing age. In a vain
attempt to avoid the inevitable, some patients deny to themselves and others
that they have a vision problem. Alternatively, they may become upset at the
realization. Kindness and gentleness can help patient overcome even these
problems.
Treatment Options
Spectacles:
 Bifocals /Trifocals
 No-line Multifocals – blended bifocals, PAL
 Multiple pairs of glasses
Contact Lenses:
• Alternating vision bifocal contact lenses – “window” bifocal, progressive
addition (aspheric)
• Simultaneous vision bifocal contact lenses – concentric design, add in the
center surrounded by the distance prescription.
• Monovision – dominant eye for distance, fellow eye for near.
• DV contact with near –vision only spectacles over them
• Modified Monovision – one DV contact lens and one multifocal contact lens
CATARACTS, PSEUDOPHAKIA, APHAKIA
“We have met the enemy and they is us,” – Pogo, by Walt Kelly
Cataracts are opacities in the crystalline that interfere with vision. They can be
congenital or due to advancing age. They can be due to trauma or medication,
exposure to radiation, monocular or unilateral. Cataracts are described by the
location in the lens that is most affected i.e. cortical, nuclear, or posterior
subcapsular. They are graded to estimate severity and monitor progress.
Signs and symptoms
If you are unimpressed by the visual problems of the cataract patient then
perhaps you were not listening to him! The most common complaints of patients
with developing cataracts are blurring distance vision, shortening of near visual
range, fatigue when he uses his eyes, acuity that fluctuates with changing
illumination, the photophobia and dazzle, glare problems, loss of depth
perception, diplopia, and even polyplopia. The most common signs are changes
in refractive error, astigmatism, anisometropia, aniseikonia, muscle imbalances,
loss of binocularity, and anomalies of accommodation.
Increasing myopia is the most widely recognized change associated with a
developing cataract. It is attributed to the increasing optical density (refractive
index) of the lens nucleus. It is also referred to as nuclear sclerosis. The
phenomenon known as “second sight” occurs when a hyperopic patient
progresses into low myopia due to lenticular changes and no longer needs
glasses to read.
CATARACTS, PSEUDOPHAKIA, APHAKIA [CONT’D]
Increases in hyperopia are less common but can also occur. A hyperopic shift is
due to an increase in the refractive density of the lens cortex. Changes in
astigmatism can also occur. This shift is lenticular and is confirmed by
keratometry readings that are unchanged from previous readings.
Monocular diplopia (polyplopia) may occur in the early phases of cataract
development. It is created by irregularities in the refractive media of the lens
and is a pinhole effect. It can be differentiated from true diplopia with the use of
an occluder.
Changes in acuity that occur in different illumination are due to the changing of
pupil size. A classic example is dramatic decreases in visual acuity that can occur
in a patient with a posterior subcapsular cataract as room light increases.
Glare is due to changes in the refractive media. It can result in complaints
ranging from discomfort to significantly decreased acuity. Controlling the
amount of light that enters the eye i.e., use of tints, hats, may decrease
complaints due to glare.
As lenticular changes occur, changes in the patient’s correction will be necessary.
These changes may involve distance, near and intermediate correction. It is
unfortunate that cataracts appear at a time of life when patients tend to become
as rigid as their crystalline lenses. In many cases full correction will maximize
acuity but the induced distortions make adaptation difficult if not impossible.
This makes compromise the name of the game.
When deciding on a prescription, as always refer to your rules of prescribing.

Use of the trial frame is critical in evaluating patient acceptance of any
prescription change. In all cases, if the patient is asymptomatic, do nothing!
If the patient has a unilateral cataract or has bilateral cataracts that are
progressing at unequal rates, arriving at a prescription requires great
consideration. Some patients complain of induced blur and that the “bad” eye
interferes with the vision of the “good” eye. Some patients develop binocular
problems especially if the eye with the poorer vision is the dominant eye.
Binocular vision may be sacrificed as the disparity increases between the two
eyes. In these cases, improving the acuity in the poorer eye is appropriate unless
the disparity increases to the point of producing a significant anisometropia
leading to aniseikonia.
Surgery
At some point, spectacles can no longer correct the progressive visual loss. Then
the treatment option becomes surgery. The decision to operate (or not) is based
on several questions:
• What is the patient’s visual disability? How is it affecting their quality of life?
• Will surgery reduce the visual disability? Is any other condition contributing
to the decrease in visual acuity?
• What are the risks of surgery? Are there other health factors that increase
inherent surgical risk?
These are questions that you and your patient should discuss. The surgeon
should also discuss them during a consultation visit with the patient.
Aphakia and Pseudophakia

Aphakia results when the crystalline lens has been removed because of a
cataract. Patients who are aphakic may be corrected by spectacles, contact
lenses, or intraocular lens (IOL). When a patient is corrected with an IOL they
are called pseudophakic. Aphakic patients are rather uncommon now since the
vast majority of cataracts extractions involve placement of a posterior chamber
IOL but they are still encountered. Many patients with congenital cataracts or
high axial myopia prior to surgery are aphakic.
Retinoscopy is generally easy on post surgical cataract patients – the ocular

media is now clear. Keratometry can give information about wound healing and
stabilization, and be used in contact lens fitting but may not give much
predicative information on cylindrical correction. In most cases full correction is
necessary with attention paid to adaptation issues.
In cases of pseudophakia, low powered ophthalmic lenses for distance vision

and near correction are necessary. These can be in the form of bifocals or
progressive addition lenses. Contact lenses are also an option.
Aphakic patients will generally need lenses in the +12.00 D to +14.00 D range.
The best way to refract these patients is using a trial frame. The vertex distance
is a critical measurement in these cases, as varied vertex distance will vary
refractive power greatly. Remember to place the strongest lens in the back cell
to measure the vertex distance. The add will be in the range of +2.00 D to + 3.00
D based on CNWD. Age is not a factor in determination of the add in these cases.
Contact lenses are an important consideration with these patients. Aphakic
corrections are unattractive, heavy, and fraught with spectacle aberrations. In
cases of unilateral aphakia, contact lenses will decrease the image size disparity
from 25-30% to a more manageable 5-7%.
Binocular Vision
As cataracts develop over time, the patient’s binocularity may be compromised.
In cases of unilateral cataract development or unilateral pseudophakia, proper
prescription will help balance good acuity and binocularity as long as possible.
Once good vision is restored to both eyes, most patients regain binocular
function approximating levels before cataract development.
LOW AMETROPIAS
“To prescribe or not to prescribe, that is the question” – Dr. Pace
Symptoms and Signs

Low Ametropias are refractive errors (myopia, hyperopia, astigmatism) of less
than 1 diopter in amount. These cases are often very challenging. These
symptoms can affect patients of all ages. For these patients, symptoms from
their uncorrected ametropia are often vague, transient, and difficult to
articulate. Clinically, examination findings for these patients are often normal or
very near normal and may then seem, to the clinician, to be insignificant. The
three most common symptoms (or patient complaints) associated with
uncorrected low ametropia are blurred vision, asthenopia and asthenopic
headache that originate with detailed visual tasks. Complaints of asthenopia may
be verbalized as eyestrain, fatigue or discomfort. Blurred vision associated with
low ametropia is often very subtle and may have little effect on visual acuity
since the defocusing of the retinal image is minimal. In cases of low hyperopia
and astigmatism, accommodation may compensate for the refractive error. Still,
effects may be manifested or intensified as asthenopia or headache when
associated with prolonged, detailed visual tasks such as occupational or
recreational reading, or computer use.
LOW AMETROPIAS [CONT’D]
The association of computers and vision related symptoms like headache, slow
refocusing between distant and near targets, diplopia, blurred vision, eye
irritation and eyestrain has been shown by many studies. Ocular factors that may
contribute are refractive error, accommodative amplitude, heterophoria, and
vergence range. Environmental factors like type of visual task, work pressure,
work intensity, and frequency of rest breaks can also be contributing factors.
Correcting these low ametropias has been effective in minimizing these
symptoms. Other potential contributing factors should also be considered before
prescribing lenses.
The predominant clinical signs of low ametropias are the objective and
subjective refraction data. A careful subjective refraction is crucial in the
diagnosis and management of low ametropias. Low myopia is usually manifested
by a reduction in acuity and is easier to identify during refraction than low
hyperopia and astigmatism. With low hyperopia and astigmatism visual acuity
often changes very little with the addition of lenses and patient response during
a subjective can be uncertain or variable.
The case history of a patient with low ametropia must clearly identify the
symptom and its association with specific visual tasks. The astute clinician will
also determine the environment in which the tasks are performed.
There is also anecdotal information that suggests that there are certain
personality types that are associated with symptomatic low ametropias. Patients
who are detail-oriented, precise, and intense may experience symptoms more
often than patients with low ametropias that are more relaxed. Regardless of
personality traits, these symptoms are real and may certainly compromise visual
efficiency and comfort.
For patients of almost any age who have symptoms there is a strong association
between the symptoms and the ametropia whether myopia, hyperopia or
astigmatism. The treatment/management strategy depends on the presence and
severity of symptoms as well as the effect of the ametropia on visual acuity.
Patient response during the subjective may help the clinician predict the
likelihood that a patient will benefit from corrective lenses. Generally the more
certain the patient response the greater the likelihood that the patient will
benefit from correction of their ametropia In these cases, the most appropriate
management strategy is to prescribe lenses to fully correct the ametropia
Modification of the prescription is generally unnecessary because the power of
the corrective lens is small. As a general guideline, the patient should use their
lenses to achieve the greatest benefit. Therefore, the patient may be instructed
to wear the lenses at certain times or for certain viewing distances or full time
based on visual complaint elicited during the history.
When low ametropia is corrected many patients report almost immediate relief
of their symptoms, especially if their symptoms arise from a specific visual task.
These patients generally adapt easily to their new prescription whether they are
habitual lens wearers or first-timers. Trial framing the prescription may help the
patient to observe the immediate improvement of the ametropia in certain
cases or may help the patient feel the improved visual comfort when performing
a visual task.
In some cases of low ametropia, such as simple hyperopia of an asymptomatic
young patient with normal accommodative amplitude, visual acuity is likely to be
near normal. In these cases, no corrective lenses for distance or near are
necessary. The patient should be educated about their condition and possible
signs and symptoms. These patients should be followed for routine care or as
necessary if symptoms arise.
Accommodation and Vergence
Full investigation of both the accommodative and vergence system should be
made prior to deciding whether correction of low ametropia will solve the
patient’s chief complaint. Problems in these two systems should be remedied
appropriately either by spectacles or vision therapy. With low power spectacle
lenses, a clinically significant effect on the accommodative vergence system is
not expected. Patients who are prescribed lenses, though, should be educated
about spectacle lens adaptation and monitored for symptoms related to
accommodative or vergence dysfunction.
BEYOND GLASSES AND CONTACTS
LASIK is short for "laser-assisted in situ keratomileusis." It is the most commonly
performed refractive surgery procedure -- partly because of the relative lack of
pain immediately afterward and partly because good vision is usually achieved
by the very next day, if not before.
An instrument called a microkeratome is used in LASIK eye surgery to

create a thin, circular flap in the cornea. The surgeon folds the flap back out
of the way. The excimer laser uses a cool ultraviolet light beam to precisely
ablate very tiny bits of tissue from the cornea to reshape it. The flap is then
laid back in place, covering the area where the corneal tissue was removed.
With myopes, the goal is to flatten the too-steep cornea. Also, excimer lasers can
correct astigmatism, by smoothing an irregular cornea into a more normal
shape. In LASEK, a trephine is used to create an epithelial flap. Advantages over
LASIK include no flap complications as in LASIK, useful for thinner corneas,
reduced dry eye effects, potential for better “custom ablation results, and can
abort to standard PRK if necessary.
In PRK (photorefractive keratectomy), an excimer laser removes tissue directly

from the surface of the cornea.
BEYOND GLASSES AND CONTACTS [CONT’D]
Both LASIK and PRK are an improvement over RK (radial keratotomy), a non-laser
procedure that involves making incisions in the cornea in a radial pattern. The
result is that the cornea is flattened, thereby correcting nearsightedness.
Drawbacks to RK include pain, lengthy healing times, regression over time, and
scarring in some people. Since the incisions go deeper into the cornea than the
laser does, many surgeons consider the surgery more invasive and therefore
potentially traumatic to the eye than PRK or LASIK. RK is rarely performed now.
Myopia (Excimer Laser)

Patient Inclusion Criteria -
1. Patients with 1.0 to 6.0 diopters of myopia are low, between 6.1 and 10.00
are considered to have high myopia, and patients with greater then 10.10
diopters of myopia are considered to have extreme myopia.
2. The attempted diopter correction is based on the patient’s true refraction.
Identifying the patient’s true refraction is the key to preventing over or
under correction. To determine the true refraction, a combination of
cycloplegic and manifest refraction must be used. Additionally, a consistent
method of refraction must be used pre and post-operatively. The spherical
equivalent must be adjusted to the corneal plane using the patient’s true
refraction and the vertex distance.
3. Stable history of preprocedural astigmatism: Patients with 0.50DC - 0.75DC
as determined by manifest refraction will have their astigmatism treated.
Manifest refraction is used because it takes into account the lenticular
astigmatism as well as corneal astigmatism. Those with 1.0DC or greater will
be treated via a toric protocol.
4. Patients will be at least 18 years of age. There is no upper age restriction.
5. Young patients with large pupils may be warned about potential problems
with glare.
Patients may be excluded due to:

1. Presence of any active ocular disease or of any systemic diseases that would
influence corneal wound healing like Rheumatoid Arthritis, Systemic Lupus,
Atopy (if present should be under good control)
2. Keratoconus or early prekeratoconus symptoms. All patients must undergo
corneal topography to rule out the presence of keratoconus. Those with K
readings of 46.00 or greater require close scrutiny to rule our keratoconus.
(Patients that require grafting may however be made contact lens tolerant by
reducing the size of the cone.)
Results
LASIK and PRK results have been notably consistent ever since the FDA approved
the first excimer lasers in1995. Best results are achieved by low to moderate
myopes, with not as good results for high myopes or hyperopes. Astigmatism
can be treated as well, though the particular type and severity of astigmatism a
person has will affect results.
Here are some numbers:

In recent studies, 98% of laser patients achieve 20/40 vision or better
after one or more treatments. (Source: TLC Laser Eye Centers) results showed
that 32% of eyes undergoing LASIK for nearsightedness achieved 20/20 or better
and 83% achieved 20/40 or better the day after surgery. Six months later, 46% of
eyes were seeing at least 20/20, with 90% seeing 20/40 or better. (Source:
data.site, an outcomes database for eye doctors) Recent studies reveal that two
thirds of PRK patients reach 20/20 or better vision, while 95% reach 20/40 or
better. (Source: American Academy of Ophthalmology) Studies of 1,013 LASIK-
treated eyes showed 92% were corrected to 20/40 or better and 47% were
corrected to 20/20 or better. (Source: FDA report of its 1999 approval of the
Summit Autonomous excimer laser for use in LASIK) Of 1,736 eyes with low to
moderate nearsightedness with or without astigmatism, about 87% achieved
20/40 or better a month after LASIK, and 93% saw 20/40 or better six months
later. The number was 45% rising to 50% for achievement of 20/20 or better.
(Source: Cataract and Refractive Surgery LASIK Study Summary of PMA Data, as
reported by LASIK Institute) An Argentina study of highly nearsighted eyes
(-10.25 to -15.00 diopters) showed average refractive error of -0.55 diopters and
average best-corrected visual acuity of about 20/30. (Source: 1998 study as
reported by LASIK Institute)
Complications
Halos and glare from bright lights at night, pain, under or over correction,
decreased contrast sensitivity at night, post-operative infection, dryness, and the
so-called "Sands of Sahara" itchiness are the main complications that patients
have reported after vision correction surgery. Fortunately, these problems don't
occur to most patients, and when they do, they are usually temporary and
treatable.
Several clinical studies report that the chance of having a vision-reducing

complication is less than 1%. No cases of blindness resulting from laser vision
correction have been reported. (Source: TLC Laser Eye Centers)
Short-term side effects of LASIK performed on 1,013 eyes included pain for one
to two days, corneal swelling, double vision and light sensitivity; some patients
experienced the effects for several weeks. Six months later problems included
under-correction in 11.9%, over-correction in 4.2%, severe halo in 3.5% and
severe glare in1.7%. Glare and halos were worse in people with larger pupils.
(Source: FDA report of its 1999 approval of the Summit Autonomous excimer
laser for use in LASIK)
For further information and demonstration of some “optical” complications see

http://www.surgicaleyes.com or http://www.LasikDisaster.com.
Phakic IOL
Implantable contact lenses, known as phakic intraocualr lenses (IOLs), are presently
being investigated as another refractive procedure. Phakic IOLs hold promise as
potentially powerful refractive tools with almost unlimited potential to correct
refractive errors. Phakic IOL are considered the best option for patients with 9-20
diopters of myopia. At the present time, however, phakic IOLs are being studied in
clinical trials to determine efficacy and safety. If FDA approved, phakic IOLs are
expected to gain wide acceptance from ophthalmologists who have implanted IOLs in
cataract patients for the past four decades with excellent results.
The phakic IOL is unique, however, in that the thin intraocular lens implant is placed
in the eye without removing the natural lens of the eye, as is completed in cataract
surgery. At present, phakic IOLs are being studied which are implanted both in front
of, and just behind, the iris of the eye. Given that the natural of the eye is not
removed, the patient retains the accommodation of the eye for near tasks.
The phakic IOL must be shown to be as accurate in correcting refractive errors as

other refractive procedures (e.g., LASIK, PRK, Intacs) and have a comparable safety
profile prior to FDA approval. At present, data regarding the potential risks, such as
cataract formation, corneal decompensation, and glaucoma, is being gathered.
Ophthalmologist investigators believe that the phakic IOL may prove to be a powerful
addition to the present refractive armamentarium, especially for those individuals
whose refractive errors presently fall out of the range for LASIK.
Astigmatism
Limbal relaxing incisions (LRI)
Limbal relaxing incisions (LRI) are truly a modification of astigmatic keratotomy
(AK), which is a procedure to treat astigmatism. LRI’s are incisions that are
placed on the far peripheral aspect of the cornea (the limbus) resulting in a
cornea that is more round. The astigmatism is thus reduced and uncorrected
vision is improved.
The procedure can be completed in a few seconds after instillation of a topical

anesthetic. There is usually little if any post-operative discomfort. The procedure
is extraordinarily safe and is not associated with glare or starburst, as often
occurs with true corneal incisions. Furthermore, the cornea is usually stable
within a week, indicating that visual fluctuations have typically resolved by that
time interval.
Limbal relaxing incisions have gained widespread acceptance amongst cataract

surgeons where it is often combined with the cataract operation to reduce pre-
existing astigmatism. This results in better post-operative vision without glasses.
The procedure can also be used in individuals whose primary refractive error is
astigmatism.
Hyperopia
Laser thermal keratoplasty LTK by Holmium Laser
A technology that received U.S. Food and Drug Administration approval

is a holmium laser from Sunrise Technologies that corrects mild
farsightedness. Called the Hyperion LTK Laser System, it works differently than
the excimer lasers now used for laser vision correction, by gently heating the
collagen in the periphery of the cornea, thereby shrinking it to steepen the
cornea's shape. The procedure is called laser thermal keratoplasty or LTK. It takes
just three seconds for each eye, and no instrument comes in contact with the
cornea. (In LASIK, a tiny sliver of cornea is cut by a keratome, lifted, and
then replaced on the eye.)
Patients must have +0.75 to +2.50 diopters of refractive error with less than
or equal to +/-0.75 diopters of astigmatism. For best results, patients must also
be 40 years of age or older, with a six-month record of refractive stability; in
other words, their prescription cannot have changed during that time period.
Patient Inclusion Criteria

Patients with 1.0 and 5.0DS hyperopia should be considered.
The attempted diopter correction is based on the patient’s true refraction. Identifying
the patient’s true refraction is the key to preventing over or under correction. To
determine the true refraction, a combination of cycloplegic and manifest refraction
must be used. Additionally, a consistent method of refraction must be used pre and
post-operatively. The spherical equivalent must be adjusted to the corneal plane
using the patient’s true refraction and the vertex distance.
Stable history of preprocedural hyperopia – this is determined by practitioner
judgment regarding the patients history including previous exam results, old
prescriptions and glasses.
Stable history of preprocedural astigmatism: Patients with 0.50DC - 0.75DC as
determined by manifest refraction will have their astigmatism treated. Manifest
refraction is used because it takes into account the lenticular astigmatism as well as
corneal astigmatism. Those with 1.0DC or greater will be treated via a toric protocol.
Patients will be at least 18 years of age. There is no upper age restriction. PRK with
hyperopic patients have results that increase with age at the time of surgery. Patients
in their 40’s have approximately a 50% success rate. Once the patients hits their 50’s
the success rate increase to 90% and then approaches 100% success when the
patients are in their 60’s.
Young patients with large pupils may be warned about potential problems with glare.
Results
The cinching effect produced at the surface initially by the radial burns initially
was effective but the regression rate is up to 80% over 6-12 months. Additionally
the procedure produces a significant amount of overcorrection and can create
irregular astigmatism.
Conductive Keratoplasty
This technique is similar to LTK except radio frequency, electrical thermal
conduction is used. A 460-micron probe delivers heat to deeper layers. Early
data shows that this procedure has less overshoot and regression than LTK.
Refractec, Inc using their ViewPoint CK System is currently developing this
procedure. The CK System was recently recommended for approval by the FDA
as the first surgical device to improve near vision or monovision. The approval
recommendation is for temporary reduction of spherical hyperopia in patients at
least 40 years old with refractive errors between +1.00 and +2.25D. The approval
was largely based on the fact that US surgeons had already performed the
procedure about 27,000 times off-label since the View Point received approval
for a separate indication in April 2002.
Clear lens replacement

For individuals over 40 who are considering refractive surgery to decrease
dependence on glasses and contact lenses, clear lens replacement (CLR) is an
exciting option. The procedure is essentially the same as a cataract extraction
with IOL with lens implant, however; in this case, the procedure is completed
prior to cataract development for the refractive advantage. The use of ultrasonic
instrumentation to measure the length of the eye to within 100ths of a
millimeter, and IOL formulas, IOL power can be determined quite accurately to
decrease the dependence on spectacles post-operatively.
CLR is a procedure that is more invasive than LASIK, PRK, and Intacs, with
consequent greater potential risks. However, CLR may be an excellent alternative
to these procedures for people already wearing bifocals or for those who do not
qualify for other refractive procedures due to extremes of refractive error.
Because CLR requires entering the eye to place the lens implant, the patient has
a small risk of endophtalmitis that is not present in the other, above-mentioned,
refractive procedures (LASIK, PRK, and Intacs). Unlike these procedures,
however, CLR avoids any treatment of the cornea and instead changes the
refractive power of the eye in a potentially more natural position (i.e., natural
lens of the eye). CLR, thus, avoids any significant risk of reduction of contrast
acuity.
Because CLR requires removal of the natural lens of the eye, the patient is
subsequently unable to accommodate at near. This is why CLR is best suited for
patients over 40 who are already wearing bifocals. One potential solution to this
problem of accommodative loss is implantation of a multifocal IOL implant. This
implant allows focusing at both near and far, allowing most patients to read
small size print and drive a car without glasses, following implantation of the
lens in both eyes. A total of 41% of patients implanted with the Array
multifocal lens in both eyes reported that they never wore glasses post-
operatively. The drawback of this lens is that approximately 15% of patients have
severe difficulty with halos and 11% have severe difficulty with glare. Less than
1% of patients have had such severe visual difficulties following implantation of
the Array lens, that they have requested removal of the lens.
A second alternative for patients who are considering CLR, but who do not
embrace the notion of wearing reading glasses following surgery, is monovision.
With monovision, the traditional monofocal IOLs are implanted bilaterally,
however, the patient’s dominant eye is corrected for distance and the non-
dominant eye is corrected for near.
This choice is also an excellent one, but not necessarily an option that would be
tolerated by everyone. An excellent method to determine whether this is a
viable option is to correct the eyes in monovision fashion as a trial, prior to
consideration of surgery. Those patients that tolerate monovision with contact
lenses (or perhaps glasses), will likely tolerate and enjoy this visual solution
following surgery with lens implants.
Corneal Ring Inserts - Intacs

Intacs corneal ring segments are an ophthalmic medical device designed for the
reduction or elimination of myopia from -1.00 to -3.00 diopters with
astigmatism of 1.00 DC or less (and patients must be 21 or older) Intacs are
removable and therefore this is the only surgical procedure that is reversible.
When placed in the corneal stroma, outside of the patient's central optical zone,
the product reshapes the anterior surface of the cornea. Intacs are composed of
two microthin prescription inserts, each having an arc length of 150 degrees.
They are manufactured from polymethlmethacrylate (PMMA) and are available
in three thicknesses, 0.25 mm, 0.30 mm and 0.35 mm. The degree of correction
is determined by the Intacs thickness. In U.S. clinical studies, 97% of patients
achieved 20/40 or better vision, 74% saw 20/20 or better, and 53% saw 20/16 or
better. (Source: KeraVision)
In patients who had Intacs implanted, about 7% experienced visual symptoms
such as glare or fluctuating vision after the surgery. In U.S. clinical studies, a few
Intacs were removed from patients' eyes, but all patients could be corrected to
20/20 or better. (Source: KeraVision)
In early 2001, Kera Vision stopped production of Intacs. Laser correction for
myopia was far more popular. Surgically, the technique to create the channels
for the Intacs was very demanding. With the development of Femtosecond
infrared cavitation lasers, creating channels has now become easier and Intacs
are gaining popularity
Orthokeratology/Corneal Refractive Therapy

Orthokeratology/Corneal Refractive Therapy is a procedure that uses a series of
rigid gas permeable contact lenses (RGPs) to change the curvature of the cornea.
Unlike regular RGPs used for everyday vision, ortho-K/CRT RGPs have
a "reverse geometry" design that can reshape the curvature of the cornea.. The
lenses flatten the epithelium centrally creating mid-peripheral epithelial
thickening. There is no change made to the stroma. The FDA has approved
reverse geometry lenses for overnight wear. After the corneas have achieved the
best shape for optimal vision, the lenses are worn less frequently – perhaps for a
few hours every two or three days. If lens wear is discontinued altogether, the
corneas will gradually regress to their original shape or close to it.
The Children’s Overnight Orthokeratology Investigation (COOKI) found no
adverse effects in 25 children ages 8-11 years old. After 6 months of treatment,
the mean uncorrected visual acuity was 20/25.
Who Is a Candidate?
The best success with ortho-K/CRT occurs in people of any age who have low
amounts of nearsightedness or astigmatism. For instance, that means if you’re
nearsighted and you have a prescription between –1.00 D and –6.00D and up to
1.75DC.The goal is to bring the person’s vision at least to 20/40 (the legal visual
minimum for driving in most of the United States). However, many people do
achieve 20/20.
Who Is Not a Candidate?

If you have four to five diopters of astigmatism and are highly nearsighted,
ortho-K will not help much.
How Long Does It Take?

Because of new advances in lens technology and design, good results
with ortho-K can occur quickly. A skilled eyecare professional can change a
person’s vision by two to three diopters in about a month. The typical time
period for ortho-K is at least six months.
The Future
Presbyopia Correction
Currently, corneal laser vision procedures cannot correct for presbyopia.
Presbyopic who receive laser vision correction must still wear reading glasses or
receive monovision.
Now, a Florida company, SurgiLight, Inc., has begun U.S. clinical trials for an
infrared laser to correct presbyopia. The company has demonstrated clinical
successes as long as 2 years at sites overseas and in Canada with more than 80%
of patients reading without glasses post-operatively. The procedure involves 8
radial cuts in the sclera to expand the globe and increase the space available for
the ciliary muscle to change the power of the crystalline lens.
Another technology for presbyopes uses a tiny scleral expansion band

(SEB), a series of four tiny segments made by Presby Corp. that are
implanted just below the surface of the sclera outside of the cornea. The
outpatient procedure is performed under local anesthesia in about 30 minutes
per eye. Right now, it’s under investigation at six U.S. clinics. The purpose of the
Scleral Expansion Band is to expand the diameter of the sclera, and thus the
distance between the sclera and the lens, so that the effective working distance
of the ciliary muscle increases.
By restoring the effective working distance of the ciliary muscle to the level that
existed within a younger eye, the muscle once again can exert enough force on
the lens of the eye to produce accommodation. Due to claims made by the
company that were false, Presby Corp. received a warning letter from the FDA
about deceptive practices.
Currently in development stages are 8 accommodating IOLs. These lens designs

include lenses with bihinged optics that move with movement of normal eye
structures and produce changes in power of the IOL and light adjustable IOL by
Calhoun (currently under animal studies). Clear lensectomies with placement of
multifocal IOLs are being investigated. Pharmacia is currently testing the Tecnus
IOL, a prolate aspheric IOL, designed to be implanted after the crystalline lens
has been removed.
The Future of Laser Vision Correction

Wavefront technology will drive the next revolution in laser vision correction. It
is currently being used as a diagnostic tool (Orbscan, corneal topographer). As a
surgical tool, it will allow custom ablations. This technology corrects higher order
aberrations and achieves maximum vision correction. It is the quantum physics
and biology of the human cornea that will be the limiting factors in achieving
maximum vision correction.
THE DISSATISFIED REFRACTION PATIENT
“If I had my life to live again, I’d make the same mistakes, only sooner.” – Tallulah Bankhead
Although, discussions thus far have covered specific visual problems and their
solutions, patients are not always so obliging as to conform to the distinct
arrangements of visual complaints and the respective solutions. Herein lies a
listing of the most common patient complaints. We will look at the symptoms
and provide the basis for analyzing them.
The Patient Complaint

The patient with the wrist-drop who dangles his glasses between his thumb and
index finger and complains that he just can’t wear these glasses is well known
even to the most conscientious practitioner. (Obviously, the more skilled the
practitioner the less frequent the complaint.) Although, there is no study that
quantifies how many patients are dissatisfied with their glasses it is estimated to
be about 6%of glasses prescribed. (Some days it may seem like the number is
higher!) This is a huge number considering it may take 15 to 60 minutes to solve
the patient’s problem!
THE DISSATISFIED REFRACTION PATIENT [CONT’D]
Some of the most common complaints are:

• The frames are uncomfortable
• The glasses won’t stay in place; they slide down their nose
• The lenses are too thick
• The glasses feel too heavy
• Vision blurs at distance
• Cannot read with the new bifocals/multifocals
• Eyes tire or “pull” with the new glasses, eyes feel better without them
• Has headaches when wearing the new glasses
• Has nausea with the new glasses
• Sees double when reading
• Objects are tilted, the ground seems to slant, or reading material seems
shorter on one side
• Vertical lines seem to curve inward –or outward-with the new glasses but
not the old ones
• Cannot walk without stumbling with the new bifocals/multifocals
• The size or shape of the bifocal is objectionable
• Objects appear too big
• Objects appear too small, too sharp
• Reflections are too annoying
Patients vary widely in their tolerance for discomfort caused by changes in their
glasses. Generally, a patient’s threshold for discomfort will depend not only on
the degree of change but also on the abruptness of change. Whenever new
glasses are ordered you must view each of the possible problems as if it could
happen to any patient.
Mechanical Discomfort with the Frames Or Lenses

The first four on this list of woes are in the jurisdiction of the
optician/ophthalmic dispenser (which in some small or rural practices may also
be YOU!) Some may be prevented by proper frame section and adjustment. Lens
design and lens material selection will help to control lens weight and thickness.
The practitioner can make recommendation at the time that the prescription is
filled to help eliminate these problems.
Vision Blurs at Distance

If the patient is aware of distance vision blur, the refraction may have been in
error. In the case of higher refractive errors the vertex distance of the new
glasses may not coincide with the vertex distance of the phoropter. Or the
prescription may not have been filled correctly. If you need to repeat the
refraction, make sure to measure the vertex distance when the refractive error is
over 5D. Hyperopes can be sensitive to the 1/6 D accommodation that is
overcorrected when refraction is performed at 6M. Targets at 100-200M will
then seem to be slightly blurry. Under correcting hyperopes by 0.25 D may help
to prevent this problem. If the patient is wearing multifocals, the placement of
the distance portion of the lens should be checked. With the patients head
straight check monocular visual acuity. If the best-corrected acuity is different
from what is the expected, have the patient move their head up and down and
side-to-side to see if there is a position where the vision improves. This is then
the location of the center of the distance portion of the lens. If this is in any
other than the straight ahead position OR the patient must move their head
differently for each eye to improve the visual acuity, then the lenses are
centered incorrectly and must be redone.
Patient Cannot Read with The New Bifocals/Multifocals

When a patient complains that he cannot read with his new bifocals/multifocals,
he is generally saying that he cannot read as well with his new glasses as he can
with his old ones. This can occur when the practitioner prescribes an add that is
too high for the patient and the patient is unwilling or unable to work at the
new, shorter working distance. Perhaps the patient was never told that an
increased add would shorten his working distance. This happens especially in
patients that are under minused at distance (i.e.; the patient with newly
developing nuclear sclerosis).
Inability to read with the new glasses or mulitfocals can also be due to poor
segment positioning. In the case of bifocals it is easy to see by comparing
segment height and inset from the old to the new glasses. In multifocals it is
more complex. One-way is to have the patient position their head so that near
vision is the clearest. Then occlude each eye alternately. I f the patient has to
move their head in order to achieve maximum clarity for either then the reading
portion of the glasses are improperly positioned.
Induced anisophoria may also cause asthenopia and can easily account for
limited reading capability. This may occur when the optical center of either (or
both) lens is off or when the new prescription has caused a disturbance in the
binocular system.
Patient’s Eyes Tire Or “Tend” To Pull With The New Glasses; He Has Headaches
And/Or Nausea With Them
If the patient has these complaints and no problem with his visual acuity, the
cause of the complaint will usually be found in some disturbance of the
binocular system. To check this, have the patient read first with one eye
occluded for a short period of time and then the other. If monocular occlusion
relieves the symptoms, the problem is binocular. But a binocular problem maybe
due to fusion problems, accommodative imbalance or induced prismatic effects.
This requires you to recheck the refraction and binocular findings. Also check the
positioning of both the vertical and horizontal optical centers of the lenses. If
any of these are off, it will induce prism.
Fatigue, asthenopic symptoms and panoramic headaches may originate from

small image size disparities, either meridional or overall. A change in the base
curve of one or both lenses may be responsible for this kind of disparity
especially in an anisometrope.
Sees Double When Reading
When a patient complains of double vision when reading, the follow up question
that you ask will help isolate the cause. If the diplopia is horizontal, the new
glasses have most likely disrupted fusion or accommodation. If the diplopia is
vertical, the cure may be binocular or poor optical center placement (and
therefore induced prism). If the diplopia is vertical and the patient is wearing a
standard bifocal like a flattop or executive, the cause may poor improperly
positioned segments. These patients may also complain of headaches and neck
pain. This is from having to position the head awkwardly to use the bifocal
segments.
Vertical Lines Seem To Curve Inward Or Outward

This bowing of straight lines may be explained by the progressive change in
magnification produced by any lens from its center to its periphery. With plus
lenses, straight lines will appear concave (“pincushion effect”); with minus
lenses the lines will appear convex (“barrel effect”) these effects are greater with
increasing lens powers.
In most cases, patients will adapt to the distortion. But sometimes to minimize
the distortion the lens curvatures will have to be increased for both plus and
minus lenses.
Minus lenses inherently have steep, inside curves that do not create much peripheral
distortion. Further increasing the curvature will reduce any distortion that is already
present and increase the magnification – frequently a desirable goal with minus
lenses. Plus lenses, on the other hand, increasing the curvature will simultaneously
increase the magnification, which may already be a problem. In these cases you may
have to choose between the two effects or compromise.
The Shape Or Size Of The Bifocal Segment Is Objectionable

This problem can be easily avoided if the practitioner, prior to ordering the glasses,
gives the patient some idea of what their glasses will look like. Discussing the options
and “Plusses and Minuses” associated with each lens type prior to filling a
prescription will minimize patient dissatisfaction with their lenses.
Objects Appear Too Big Or Too Small

“Fore warned is fore armed” seems to apply here. The practitioner should discuss the
possibility of objects appearing larger and closer to a hyperope when increased plus
is required. If this is a problem, decreasing the center thickness of the lens may help
ameliorate it. When myopic patients complain of minification, it is sometimes
because they have been overcorrected. This requires the practitioner to recheck the
refraction. There is the occasional myope who prefers to be under corrected. They
don’t like things “too clear”. Hopefully, trial framing the proposed new prescription
will have uncovered this fact.
The Investigative Routine

Whenever a patient presents with a complaint associated with new glasses, it is
helpful to have a standardized course of action for investigating the problem. Of
course if the cause of the problems is obvious, or becomes clear early in your
routine, there is no need to complete the routine fully.
LISTEN! The patient may be able to pinpoint the problem quickly. A few
moments of conversation may help determine quickly if the problem is optical,
mechanical or psychological.
Take visual acuity with the new AND the old glasses and compare. If the glasses
are bifocals take both distance and near acuities.
Neutralize the lenses with the lensometer.
Mark the optical centers and the centers of the bifocal segments. If multifocals
use your lens guides to mark the centers of distance and near portions of the
lenses. Compare optical centers of new and old lenses and patient’s PD.
In cases with high refractive errors measure the vertex distance, ccmpare the
vertex distance of the new glasses to that of the old or the vertex distance of the
phoropter.
Evaluate visually the frame adjustment of the new glasses. Remember to check
for the correct pantoscopic tilt.
Check base curves with a lens clock on both old and new glasses.
With bifocals or multifocals –check to see the reading segment is at the proper
height relative to the patient’s pupils.
Measure the height of the near segment (it’s vertical dimension). It should be at
least 12mm high to give an adequate near field.
Compare frame size to the old glasses. An abrupt increase in frame size can
cause an exacerbation of lens aberrations.
Inspect the lenses for scratches, waviness or other evidence of defective
finishing.
At this point, if you find that neither the new lens nor the frame is at fault, you
should reevaluate the patient’s complaint and their history especially looking
into specific visual requirements and repeat the refraction. Accommodative
ranges should be measured and heterophorias should be measured again.
Astonishingly, you will sometimes find that the error has been yours!
In cases with high refractive errors measure the vertex distance, ccmpare the
vertex distance of the new glasses to that of the old or the vertex distance of the
phoropter.
Evaluate visually the frame adjustment of the new glasses. Remember to check
for the correct pantoscopic tilt.
Check base curves with a lens clock on both old and new glasses.
With bifocals or multifocals –check to see the reading segment is at the proper
height relative to the patient’s pupils.
Measure the height of the near segment (it’s vertical dimension). It should be at
least 12mm high to give an adequate near field.
Compare frame size to the old glasses. An abrupt increase in frame size can
cause an exacerbation of lens aberrations.
Inspect the lenses for scratches, waviness or other evidence of defective
finishing.
At this point, if you find that neither the new lens nor the frame is at fault, you
should reevaluate the patient’s complaint and their history especially looking
into specific visual requirements and repeat the refraction. Accommodative
ranges should be measured and heterophorias should be measured again.
Astonishingly, you will sometimes find that the error has been yours!
On The Prescription Pad

Errors may sometimes be avoided and time saved by including supplementary
information on the prescription. The following information may be provided:
Vertex Distance, especially in high refractive errors.
Bifocal segment position especially if there is a specific visual requirement.
Type of bifocal or multifocal, based on previous glasses, occupation.
Material of lenses especially if they are other than standard Cr-39.
Tint or absorptive finishes.
Include optical separation, including the decentration if you want to add prism
to the prescription by decentration.
If there is any facial asymmetry, it must be considered on the prescription.

Asymmetry may be vertical or it may be an unequal distance between the
pupillary center of each eye and the bridge of the nose. Other anatomical
problems – like old nose fractures, and exophthalmos should be considered.

Optometric Case Analysis

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What are the general principles of medical record documentation?

What are the general principles of medical record documentation?

What information should be included when documenting a patient encounter?

What information should be included when documenting a patient encounter?

Optometric

The medical record is a medico legal document. The information

The medical record is confidential. If the patient requests a copy of

The principles of documentation listed below are applicable to all types of

Identifying and Satisfying the Patient’s Needs

“The Science of a Taking Case History”

. History of Present Illness (HPI) The HPI is a chronological description of the

3. Review of Systems (ROS) ROS is an inventory of the body systems obtained

During an optometric examination, the ocular history should include a thorough

Any positive response should be explored thoroughly. When recording a history,

“The Art of Taking A Case History”

Problem – a sign or symptom presented by the patient.

Every fact has an element of value, substantive and abstract, whose

Data collection consists of historical information (patient and family), results

Other diagnostic strategies

Therapeutic implications of available accommodation are self-evident in the

Most clinicians today aim at under correction of hyperopia. Donders suggested

SIMPLE! Refraction is normally performed with the distant acuity target 6m or 20

Solution: Instead of trying to guess which hyperopes may complain about

Table from “Refractive Management Of Ametropia”, KE Brookman

Once myopia appears in childhood it generally increases (myopic progression)

The patient says the previous lens was better

Associated Binocular Anomalies

Overcorrection of myopia will stimulate accommodation and therefore

Astigmatism is the ametropia created by meridional variation in refractive

A more conservative approach is to give a full prescription to patients who have

In patients whose personalities are highly critical, anxious, or meticulous, a

How do I modify the prescription?

A distance-to-near change in cylinder axis of greater than 5 or cylinder power

Anisometropia can be broken into five categories:

The symptomatology of uncorrected anisometropia depends not only on the

The device of choice to measure the amount of aniseikonia has long

Common exam findings associated with presbyopia are

When deciding on a prescription, as always refer to your rules of prescribing.

Aphakia and Pseudophakia

Retinoscopy is generally easy on post surgical cataract patients – the ocular

In cases of pseudophakia, low powered ophthalmic lenses for distance vision

Symptoms and Signs

An instrument called a microkeratome is used in LASIK eye surgery to

In PRK (photorefractive keratectomy), an excimer laser removes tissue directly

Myopia (Excimer Laser)

Patients may be excluded due to:

Here are some numbers:

Several clinical studies report that the chance of having a vision-reducing

For further information and demonstration of some “optical” complications see

The phakic IOL must be shown to be as accurate in correcting refractive errors as

The procedure can be completed in a few seconds after instillation of a topical

Limbal relaxing incisions have gained widespread acceptance amongst cataract

Laser thermal keratoplasty LTK by Holmium Laser

A technology that received U.S. Food and Drug Administration approval

Patient Inclusion Criteria

Clear lens replacement

Corneal Ring Inserts - Intacs

Orthokeratology/Corneal Refractive Therapy