Fitting the Soflex ND

Moodi Kupperman B.Sc Soflex

GP Lenses in your Clinique

Advantages to your customer

Improved corneal health Sharp, stable and clear vision Easy to handle Economic and easy cleaning process Comfortable throughout entire day Long lens life

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GP Lenses in your Clinique

Advantages for you

Less chair time More profit Customer loyalty Less health problems for your customers eye

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100 years from glass to GP, contact lens History

1508 Leonardo da Vinci illustrated the concept of contact lenses 1823 British astronomer Sir John Herschel conceptualized practical lens design 1887 First contact lens manufactured from glass, and fitted to cover the entire eye 1939 Contact lenses first made from plastic 1948 Plastic contact lenses designed to cover only the eye's cornea 1971 Introduction of soft contact lenses 1978 Introduction of GP contact lenses 1981 FDA approved new soft contact lenses for extended (overnight) wear 1986 Overnight wear of GP contact lenses became available 1987 Introduction of disposable soft contact lenses 3/16/2013 1987 GP contacts available in next-generation 4 fluorosilicone acrylate materials

Silicone Fluroine

Methacrylic Acid Methylmethacrylate HEMA MMA

Polymer (in Greek) = Poly - many, Meros - parts

Fluoro-Silicone-Acrylate
Fluorine, Silicone Methacrylic acid (Hema) = = = Oxygen permeability Wetting agents

MethylMethAcrylate (MMA) 3/16/2013

Mechanical and optical stability

RGP Lens Properties

Oxygen permeability / Oxygen Transmissibility
Surface characteristics Wettability, reactivity Dimensional stability Flexural resistance Hardness Fracture resistance Specific gravity Index of refraction Machining capabilities

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Oxygen Transmissibility
Dk - Is the materials permeability to oxygen. Dk/t - Is the materials oxygen transmissibility t - Is the thickness of the lens.
Standards for measuring Dk
O2 O2 O2 O2 O2 O O2 O2 O2 O2O2 2 OO 2 2 O2
0.10 mm

O2

O2 O2 O O2 2 O O2 2 O2 O2 O2 O2
0.20 mm

The higher the Dk/t number the greater 3/16/2013 the oxygen transmissibility !

Coulometric Polarographic ISO Fatt ISO Fatt (revised) mm Hg hPa

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MeniconZ=168

HDS100 Bxo Optimum Extra =100 Optimum Comfort=65 HDS=58 S4=32 S3=18

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Other Techniques for Measuring In Vivo Oxygen Transmissibility

Overnight Corneal Swelling Biochemical corneal changes Epithelial mitosis Corneal sensitivity Limbal vascular response

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Limbal Redness

Low Dk CL

High Dk CL

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Silicone

Fluorine

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Measurement of the Material Wetting Properties In Vitro

Sissile Drop in air Captive Bubble in water Wilhelmy Plate Dynamic in water
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RGP Surface Modification

Bulk properties Molecular membranes Plasma treatment Plasma polymerization
Treated Surface

Untreated Surface

Monomer

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RGP Surface Modification

Manufacturing Induced Non-Wetting Residual Blocking / Polishing Pitch

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RGP Surface Modification

Manufacturing Induced Non-Wetting Excessive Solvent Exposure

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RGP Surface Modification

Manufacturing Induced Non-Wetting Excessive Heat Exposure

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Plasma Treatment
The Cleaning stage

Oxygen Surface Contaminant Plasma

The oxygen plasma hits the lens surface with such force that it breaks-up any surface contaminants such as waxes, polishing pitch and residual residue left on the lens.
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Plasma Treatment
The Surface Modification Stage

Electron ejected from a gas (oxygen) Bombard the contact lens surfaces The reaction between the gas molecules and the surface silicon molecules alters the hydrophobic silicon surface chemistry 3/16/2013 to one that is significantly more hydrophilic

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Plasma Treatment

BEFORE
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AFTER
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Base Curve Radius Stability

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Flexural Resistance
In Vitro Laboratory measurement

In Vivo Residual astigmatism

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RGP Surface Scratches

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Fracture resistance

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Specific gravity
Superior Lens Position Inferior Lens Position
Material name
Menicon z Optimum Extra HDS100

Specific Gravity
1.200 1.160 1.100

Bxo

1.270
1.170 1.160 1.140

Centered Lens Position

Optimum Comfort HDS S4

S3

1.126

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Material Index and Add Power

Higher index materials can be made thinner while maintaining the same refractive power
low n

Material
PMMA

I/R
1.490

Add Pwr
+1.75

HDS
HDS 100

1.449
1.453

+1.25
+1.25

Menicon Z
Bxo
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1.440
1.415

+1.25
+0.75
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high n

Raw Material Properties

Material name Menicon z Optimum Extera HDS100 Bxo Optimum Comfort HDS S4 S3
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Wetting Angle

Oxygen Permeability (Dk)

Hardness
(Rockwell R)*

Refractive Index

Specific Gravity

24 3 42 49 6 14.7 12.8 30

160 100 100 100 65 58 32 18 112.0 105.5 100.0

1.440 1.431 1.442 1.415 1.437 1.449 1.446 1.470

1.200 1.160 1.100 1.270 1.170 1.160 1.140 1.126 39

PMMA

1.490

All Soflex gas permeable lens design are available in all the above materials !!!

Ski, Soflex ND, Tri, OP2, OP5, OP8 OPT, SPHRD

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The Soflex ND
Soflex - ND is our Polish Free flexible Gas Permeable contact lens which is incredibly comfortable for customers to wear and convenient for practitioners to fit. The lens base curve has a unique aspheric optic zone and continuous periphery that controls the edge lift and rounds the edge. This revolutionary design allows maximum comfort and easy fitting.
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The Soflex ND
Soflexs Soflex - ND is produced on computer controlled diamond turning lathes using advanced raw materials. This combination together with Plasma treatment gives the lens excellent wettability, high oxygen permeability and reliable parameter stability.

Fast Tool Servo

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Polish Free
High reproducibility rate Excellent optics Accurate parameters Stable parameters High quality surface finish High comfort all day long

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Fitting the Soflex ND

1. Initial data gathering 2. Lens Fit Analysis 3. Ordering of the Soflex ND, RGP lens
Rh Rv Axis Sph Cyl Axis HVID BUT

R 3/16/2013 L

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Initial data gathering

Recent routine refraction note the visual acuity and back vertex distance. Full eye examination including a slit-lamp assessment. Keratometry and/or Topography

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Initial data gathering

Tips:
Measurements are required of the Horizontal Visible Iris Diameter (HVID), the vertical palpebral aperture, and the pupil diameter in various illumination conditions. The HVID gives an initial clue as to the overall lens diameter, usually approximately 2 mm less than HVID.
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The position of the eye lids is important. The Soflex - ND lens should be fitted using the lid attachment method Tear film quantity and quality assessment using the slit lamp. Observing the tear prism Tear break-up time with fluorescein
-

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A suitable Soflex - ND lens is selected from the Trial Set Box based on the available information and inserted into one eye. An assessment and note of the lens fit and performance is made. Suitable modifications may be suggested to improve the fit and these may be discussed.

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Lens fit analysis

The first choice Soflex - ND lens has a Back Optic Zone Radius of curvature (BOZR) nearest to the flattest keratometry K reading. An aspheric lens design is more likely to closely follow the midperipheral corneal contours, to spread the lens pressure on the cornea more evenly and to improve comfort. For this lens design the lens BOZR on flattest K is preferable. An aspherical design lens can often mask corneal astigmatism better. Tip: For each 0.75D corneal astigmatism reduce 0.05mm from lens BC (steeper)

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Effect of Lens Thickness

If a lens has a back vertex power (BVP) of greater than +4.00D, the lens front surface shape and thickness may affect the fitting. A steeper fit would often be needed If the lens power is a high minus power of greater than -7.00D, the center of gravity is posterior to the corneal apex and the lids can grasp the relatively thicker lens transitional zone to lift the lens. A flatter fit and larger diameter would often be needed.
+7.00
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-3.00
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-7.00

Lens Diameter
The Soflex - ND lens Over All Diameter ( OAD ) is 9.60mm Standard Diameter 9.00 and 10.20 are also available upon request
A large overall lens diameter may be preferred in order to help pupil coverage, to assist lens centration particularly if the palpebral aperture is wide, and in some cases to stabilize the lens fit if there is excessive lens movement. A small lens diameter is used where palpebral aperture is small

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Lens Fit
The Soflex - ND lens fit is assessed after a drop of fluorescein is instilled, the patient blinks several times and the fluorescein pattern observed using the Burton lamp for a general view with the patients head in a natural position. The slitlamp with the cobalt blue filter can be used for a more detailed view of the lens fit pattern and tear flow. The lens centration, movement and fit should be noted, both in the primary position of gaze and on various eye movements.

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Fluorescein pattern
Flat fit
An apical bearing fluorescein pattern reflects a flat fitting relationship. Photo shows a Flat Pattern. This relationship can ultimately result in corneal distortion in the region of bearing. This can be easily managed via selecting a steeper base curve radius.

An apical bearing

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Fluorescein pattern
Steep fit
An apical clearance fluorescein pattern reflects a steep fitting relationship. Photo shows a Steep Pattern. This can cause peripheral seal off, resulting in poor tear exchange and possibly adherence. Select a flatter base curve radius to improve the fitting relationship.

An apical clearance

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Fluorescein pattern
Normal fit
Strive for an alignment ("even") fluorescein pattern. This is not necessarily equal to an "On K" base curve selection due to the asphericity of the cornea. Photo shows an Alignment Pattern.

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A good fit shows

- Satisfactory lens centration. - With lids held apart, the lens should slowly drop downwards. - With normal lid position, the lens peripher should not move beyond the limbus. - Alignment type fluorescein pattern shows alignment or slight apical clearance over the central 7.00mm region, mid-peripheral touch and edge clearance of about 0.50mm width.

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Lens ordering
The ocular refraction (Oc.Rx) at the corneal plane can be calculated from the spectacle prescription and the back vertex distance (BVD). See Back Vertex Correction table ( There should be an approximate change of 0.37D for every 4.00 diopters of power. ) Trial Lens: Soflex ND 9.60 7.80 Over refraction: Soflex ND 9.60 7.80

-3.00 -5.25 -8.00 / Raw Material / Clinique name / Px name

The ordered lens specification must be clearly written.

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Choice of the raw material

The Soflex - ND is manufactured from state of the art raw material Optimun Comfort as a standard. This material has excellent wettability and deposit resistance, high oxygen transmissibility and very good physical properties, however we are also able to manufacture the lens from other materials depending on your patients needs.
Tip: The choice of RGP lens material will depend on physiological characteristics of the patient.

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Lens Parameters
Lens Specifications:
Material Optimum Comfort Surface Treatment: Base Curve : Diameter: Central Thickness: Sphere Power: Back Design: Front Design Spheric: Plasma 7.00 to 8.40mm 9.60, 10.20mm ( 9.00mm ) 0.16 mm @ -3.00DS Any Medium Asphericity + Blended Bevel Sphere + Lenticular DK 65 x 10 -11 @ 35 Tint Blue,Green

For diameters and base curves outside the standard range, please inquire

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Cleaning and disinfecting

Cleaning and disinfecting the Soflex - ND lenses is an important procedure that must be performed immediately every time lenses are removed. Cleaning is necessary to remove mucous, film and residue on the lens surface, while disinfecting is used to prevent germs from causing eye infections. There are many different brands of lens care products available for GP contact lenses.

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Follow up
The practitioner is reminded that successful Soflex ND lens fitting is not just obtaining a contact lens of correct curvature and power, but includes educating the patient in the appropriate wear and care of the lens and continuing to monitor the eye at the regular aftercare visits.
Tip: Remember - Follow up regime is essential

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Fitting tips
Fitting Tip Checklist
Parameter Changes - Change base curve radius (BCR) a minimum of +/-0.1mm ( from the Trial Set ) - Change overall diameter a minimum of 0.6mm To maintain the same fitting relationship: - Select 0.05mm flatter BCR for every 0.6mm increase in diameter (i.e., if large pupil size) - Select 0.05mm steeper BCR for every 0.6mm decrease in diameter (i.e., small fissure size)
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Thanks
Questions