DE102013022302A1 - fundus camera - Google Patents

Abstract

The invention relates to a fundus camera (1) for photographic observation, documentation and / or diagnosis of the retina of an eye (2), which comprises the following features: an illumination module (10) with a light source (11) with limited area for generating an illumination beam path, an image plane (B3) in the illumination beam path for the creation of photographic recordings, an image area (23) which represents the image of the fundus (3) on the image plane (B3), a digital camera (16), a detection beam path between the digital camera (16) and the fundus (3), means for dividing the detection beam path into a detectable observation area (26) and a non-detectable illumination area (27); The invention is characterized in that a slit diaphragm (14) for limiting the image area (23) to an illuminated strip (24) of the fundus (3) is provided next to unlit areas (28a, 28b), a patient guidance module (20) is provided, by means of which the region of the fundus (3) to be examined can be changed to the position of the illuminating beam path and the detection beam path by targeted guidance of the patient's line of sight and the illuminating beam path and / or the detection beam path is or are stationary relative to the overall structure of the fundus camera.

Description

The present invention relates to a fundus camera for the photographic observation and / or documentation of the fundus of an eye, in which the production of photographic images preferably without the need for a Mydriatikums d. H. a pupil dilating drug takes place.

Technological background

With a fundus camera, also called "retina camera" or "ophthalmoscope", photographic images of the fundus (fundus) are made. Such recordings support ophthalmological diagnostics. They are used to visualize and document pathological changes in the retina. A fundus camera is equipped with an illumination source, illumination optics, and a digital camera that allows the production of high-resolution images, which can be stored in a digital patient file or stored in printed form in the patient map.

Due to the illumination, a fundus camera experiences artifacts due to back reflections of the illumination source at various locations in the eye. These back-reflections are also called Purkinje reflections.

The fundus cameras currently on the market can be divided into the following different groups of devices, depending on the method of artifact suppression.

The first device group uses an annular pupil division. While the pupil is illuminated by an external illumination ring, the light scattered back from the fundus is detected by a circular, exposure light-free central zone of the eye pupil. To delimit the outer illumination ring from the inner detection area of the eye pupil, a narrow transition zone is provided between the two areas in which neither is illuminated nor detected. This transition zone is expedient, as a result, a complete separation of illumination and detection beams not only in the cornea plane but in the entire eye anterior chamber, d. H. from the front of the cornea to the back of the eye lens. Although such fundus cameras allow free images of the fundus to be recorded due to the separation of illumination and detection of Purkinje reflections, the achievable fundus angle is dependent on the diameter of the pupil due to the annular pupil division. In a non-mydriatic eye, d. H. in an eye that has not previously been treated with a pupil-dilated drug (mydriatic), the detection field is very limited.

Furthermore, there are methods in which polarized light is used to avoid or reduce back reflections, especially those back reflections that arise within the optics of the fundus camera.

There are also so-called line-scanning methods in which a luminous line is produced on the fundus, which is moved (scanned) perpendicular to its orientation over the fundus. During this process, the fundus is imaged onto a digital camera so that a complete fundus image is exposed.

Nearest prior art

A fundus camera according to the preamble of claim 1 is made El-Bayadi, George: New Method of Slit-Lamp Micro-Ophthalmoscopy, In: Brit. J. Ophthal., Vol. 37, 1953, pp. 625-628 known. In this fundus camera, a slot-shaped illumination beam path is used, which illuminates a strip-shaped part of the pupil cross-sectional area, whereas the non-illuminated area of the pupil cross-sectional area serves the observation beam path. With a relatively wide, slit-shaped illumination area combined with an expansion of the pupil with the aid of a mydriatic, an observation of the fundus without reflexes can be carried out in this known fundus camera.

Out Higher, B .; [Et. Al.]: Non-mydriatic, 68 ° wide fundus imaging with low cost components. In: Abstract of the ARVO Annual Meeting 2012, May 2012 It is known to divide the image area semicircular in an illuminated semicircle, which serves the investigation, as well as an unlit semicircle, which serves to shield the reflections. In this way, a certain reduction of the reflections in the semicircle to be observed can be achieved. Nevertheless, a reflection component remains in the area to be examined, which adversely affects the image quality.

From the WO 2012/059236 A1 a fundus camera with strip-shaped pupil division and a method for recording artifact-free, high-resolution fundus images is already known. In this case, a strip-shaped pupil division of the eye to be examined in the form of a vertical, the illumination zone characterizing beam and bilateral, the detection zones of the pupil performing circle segments made. In addition, by means of a slidable slit of the illumination source, the exposure limited to a split shape and scanned over the ocular fundus.

The light reflected by the retina falls as an image of the gap on the respective sectors of a spatially resolving detector and can be read there. Purkinje reflections are recorded using this method. In order to avoid these reflections on finished photographs, a second image (dark image) is taken of each recorded light image and subtracted from the light image to eliminate the disturbing reflections.

Object of the present invention

The object of the present invention is to provide a method for photographic observation, documentation and / or diagnosis of the type described above, by means of which on the one hand without administration of Mydriatikums a very large area of the retina can be taken without disturbing reflexes, on the other hand the use a particularly cost-effective variant of a fundus camera is made possible.

Solution of the task

The above object is achieved in the generic fundus camera by the characterizing features of claim 1. Advantageous embodiments of the invention are claimed in the dependent claims.

The fundus camera according to the invention according to claim 1 allows the inclusion of strip-like areas of the retina, combined with the possibility of a very simple and therefore cost-effective apparatus design. The invention also provides the possibility of receiving a very large area of the retina along the longitudinal axis of the strip. By eliminating the possibility of administering a mydriatic, increased patient comfort is created. The illumination beam path and / or the detection beam path during a recording relative to the overall structure of the fundus camera is stationary, d. H. no variable translational movement relative to each other and relative to the eye exposed. Elaborate cost-intensive mechanical components can be eliminated.

Because the detectable observation area and non-detectable illumination area have a semicircular or circular segmental shape, the third and fourth Purkinje reflection can advantageously be imaged into unused areas, in particular in conjunction with an approximately punctiform or at least limited illumination source with a high beam power per area.

If the aperture plane A1 is displaced from the pupil back into the eye, preferably into a plane at the front of the lens of the eye or at least into a plane in the region of the lens of the eye, the front lens surface is penetrated by a convergent beam and the rear lens surface Lens surface of a divergent beam. Due to the opposite curvature of the surfaces of the lens of the eye, the reflection of the illumination beams results in a parallelization of the reflected radiation bundles. The aperture plane A1 is thus imaged infinitely, so that it has the focal position "infinite" just as well as the fundus image. This leads to an at least substantially sharp image of the aperture plane A1 and thus also of the light source on the photosensitive electronic component of the digital camera. As a result, the third and fourth Purkinjereflexion be reduced to particularly small surface areas in the fundus image and can therefore be accommodated in the edge regions of the strip-shaped trisection of the image area.

In the fundus camera according to the invention, the strip-shaped illuminated area of the image area corresponds to an image angle in the transverse direction to the strip of a maximum of 5 ° to 30 °, preferably of 18 ° to 24 °, particularly preferably of 20 ° to 22 °.

Likewise, the strip-shaped illuminated area of the image area corresponds to an image angle in the longitudinal direction to the strip of 40 ° to 90 °, preferably 64 ° to 72 °, particularly preferably 66 ° to 70 °. The method thus makes it possible to image a very large area of the retina.

By varying the area of the fundus to be examined in the illumination beam path and the detection beam path by changing the viewing direction of the patient's eye relative to the alignment of the illumination beam path and / or detection beam path, areas can still be created in this way with a stationary illumination beam path and / or detection beam path the fundus, which go beyond the illuminated strip, are displayed and preferably combined to form an overall picture. As a result, the area of the fundus to be examined can be considerably enlarged. It is also possible to reduce the image angle of the illuminated area of the image area in the transverse direction to the strip, for example to less than 20 °, preferably to less than 18 °, particularly preferably to less than 16 °, in order to further reduce the scattering effects of the light source.

The "guidance" of the human eye is expediently carried out to produce a fixation mark which can be changed in position and imaged on the fundus and therefore seen.

Optionally, the fixation mark can be recorded and documented by the camera.

Conveniently, a fixation mark is generated separately for each eye and used for patient guidance. In contrast to monocular procedures, the frequently observed "instrument accommodation", ie a disturbance of the automatic distance control in the brain, is avoided. In addition, this method allows a case-based variation of the accommodation and / or the convergence. Without the use of moving parts, in the fundus camera according to the invention preferably both a variation of the accommodation, by variable focus and the convergence can be achieved by vertical movement of the fixation mark.

The fundus camera according to the invention makes it possible to cover an overall image with respect to the transverse direction to the course of the strip-like division with an image angle of at least 45 °, preferably at least 60 °, particularly preferably at least 65 ° of the fundus, d. H. map.

The fact that the third and the fourth Purkinjereflexionen R3 and R4 are shown in the fundus sharply, they can be used as an optical reference position for determining the relative position of the detection optics with respect to the viewing direction of the eye.

The fundus camera according to the invention expediently comprises an eyepiece with a field diaphragm, as a result of which the image field can be limited over a wide angle. It is advantageous to use a commercial eyepiece z. B. from the field of amateur astronomy or microscopy to use, which brings the advantage of optimally adapted to the eye optics and low cost due to mass market availability.

The oblique orientation of the display to the image plane B5 allows the focus to be changed without the use of moving parts (solid state device) by moving horizontally the fixation mark (pixel) indicated on the display, which increases the distance of the fixation mark on the display to the projection lens of the display Displays changed. This variable focusing possibility allows an adjustment of the accommodation of the patient, taking into account any refractive errors.

The use of the colors infrared, green and ultraviolet (IRGUV) to illuminate the fund has the advantage that color images can be obtained even when using a black-and-white digital camera. The fact that a black and white digital camera compared to a color digital camera has a higher light sensitivity, the intensity of the illumination and the resulting patient load can be reduced when using a black and white digital camera. To produce color images, black and white images are sequentially taken and each illuminated with different colors, infrared, green or ultraviolet. The three images produced in this way are assigned to the three primary colors red, green and blue and a color image is reconstructed by means of additive color mixing on the computer. This method requires a lower burden on the patient due to the reduced exposure to light and by reducing or avoiding disturbing afterimages. The lower illumination intensity also achieves a reduction in the influence of the pupil-closure reflex, as a result of which a better image can be achieved due to a larger pupil. In addition, an infrared preview mode for aligning and centering the fundus camera is possible in a simple manner.

According to one embodiment of the invention, it is provided that a plurality of grayscale images of the fundus are recorded sequentially, wherein in each case only a single LED of the light source is active.

In accordance with a further embodiment of the invention, it is provided that one or more dark reference images are recorded per emission wavelength of the light source, in that the eye is replaced by a light absorber.

According to a further embodiment of the invention, it is provided that one or more light reference images are recorded per emission wavelength of the light source, wherein the eye is replaced by a diffuse reflector which serves as a white reference.

In accordance with a further embodiment of the invention, it is provided that artifacts in the fundus images and image noise are at least partially removed by respectively subtracting from the fundus images a dark reference image or the averaging of a plurality of dark reference images.

According to a further embodiment of the invention, it is provided that a color balance and a reduction of the image noise can be achieved by a pixel-by-pixel division of a fundus image by a light reference image or by the averaging of several light reference images.

According to a further embodiment of the invention, it is provided that a plurality of greyscale images of the fundus, which were respectively recorded at different emission wavelengths of the light source, are combined to form a color image, false color image or multispectral image, preferably a relative shift and / or rotation and / or scaling of the gray scale images is made beforehand, so that in the combined image the depicted structures of the fund are brought to coincide.

According to a further embodiment of the invention, it is provided that a plurality of grayscale images, color images, false color images or multispectral images are calculated so that the resolution is increased and / or the noise component is reduced and / or the visible region of the fundus is increased.

According to a further embodiment of the invention, it is provided that a video sequence is generated from a plurality of fundus images which have been produced according to one or more of the abovementioned methods. This has the advantage that the examination can also be combined with examination methods (eg fluorescence angiography), preferably simultaneously.

The patient guidance module makes it possible to guide the patient's eye while at the same time allowing a change in the accommodation and compensating for refractive errors by focusing without moving parts in the apparatus design.

Description of the invention with reference to embodiments

In the drawings, exemplary embodiments of the present invention will be explained in detail.

Show it:

1 a representation of a first example of an en Fundus camera;

2 a representation of the strip-like division of the image surface in lighted and unlit areas in the fundus camera after 1 ;

3 a division of the aperture (pupil) in the fundus camera after 1 ;

4 a photographic image of the image area according to 2 ;

5 a highly simplified representation of a photograph taken with the fundus camera according to the invention of an enlarged area of the retina;

6 an expedient embodiment of erfindungemäßen patient guide module for use in a fundus camera with enabling a variable focus.

7 an example of a binocular patient guided fundus camera according to the present invention;

The reference number 1 in 1 denotes the fundus camera according to the invention in its entirety. The fundus camera 1 serves to the ocular fundus of an eye 2 to investigate and take photographic pictures of it.

When lighting the fundus of the eye 2 If there are any picture disturbances (artifacts) in the fundus image due to the back reflection of the illumination source. These artifacts are also referred to as "first to fourth Purkinje reflections." The place of origin of these Purkinjereflexionen R1-R4 are with F1-F4 in 1 characterized. They occur in different places in the eye. The first Purkinjereflexion R1 occurs at the front of the cornea 5 (Cornea) and is by far the strongest. The second Purkinjereflexion R2 occurs at the back of the cornea 5 on. The third and fourth Purkinjereflexionen R3 and R4 occur at the front and back of the lens 4 of the eye 2 on.

The fundus camera 1 includes a lighting module 10 with an approximately punctiform light source 11 , preferably in the form of an LED module. The LED module includes three emitters, with the colors infrared, green and ultraviolet. The use of the colors infrared, green and ultraviolet makes it possible to use a black and white camera, which has a higher light sensitivity compared to a color camera, whereby the intensity of the illumination and thus the patient load can be reduced. The switching on and off of each LED emitter is controlled by a microcontroller 29 and a computer 31 controlled (see also 7 ).

The collimators 12 and 15 form the approximately punctiform light source 11 on the mirror 9 from. A polarizing filter 13 serves together with another, in front of the digital camera 16 positioned polarizing filter 19 in addition, reflections in an eyepiece 6 and in the eye 2 mitigate. Furthermore, a slit diaphragm 14 provided by means of which generates a strip-shaped illumination area and on the fundus 3 is shown (see area 2 in 2 ).

As a device for the production of digital, photographic images of the fundus 3 becomes a digital camera 16 , preferably a digital black and white camera used. The digital camera 16 for example, has a resolution of two megapixels. The digital camera 16 comprises a photosensitive electronic component 17 for capturing two-dimensional electronic images. Furthermore, the digital camera includes 16 a lens 18 , Into the digital camera 16 For example, an autofocus unit can be integrated to compensate for spherical refractive errors. The fundus camera 1 further includes the eyepiece 6 , whose adaptation to the structure of the fundus camera 1 through a field lens 7 is made. With 20 a patient guidance module is identified. This serves to bring about a guided change in the viewing direction of the patient by means of a patient guidance module 20 to cause generated fixation mark. This ensures that selected areas of the fundus can be imaged, ie, detected. Partial recordings can thus be combined into a comprehensive overall representation of the fundus.

The reference number 22 denotes a display, preferably a so-called OLED display, for generating the electronic fixation mark. The the display 22 upstream display projection optics 21 forms the display 22 with the fixation mark produced thereon on the intermediate image plane B2 in the eyepiece 6 from. The beam splitter 8th serves to the patient guidance module 20 to integrate into the construction.

In the optical design of the fundus camera 1 There are the image planes B1 to B5, which are imaged by lenses. The image plane B1 lies on the fundus 3 of the patient. The patient "sees" this picture. The image plane B2 represents an intermediate image inside the eyepiece 6 whose image section is bounded by the field stop in the horizontal direction in the example of 2 on a circular image section corresponding to a viewing angle of 68 °. The image plane B3 represents the image displayed on the photosensitive electrical component 17 the digital camera 16 lies. This picture of the picture plane B3 "sees" the camera. The image plane B4 forms the homogeneously illuminated gap of the slit diaphragm 14 from. The image plane B5 is the image plane of the display 22 in which the fixation mark is generated.

If an object is located in one of the image planes B1 to B5, it will be displayed in all other image planes. From the image plane B1 to the image plane B3, the fundus on the photosensitive electronic component 17 the digital camera 16 displayed. From the image plane B4 to the image plane B1, the homogeneously illuminated gap of the slit diaphragm 14 on the fundus 3 with uniform illumination of the same pictured. From the image plane B5 to the image plane B1 is via the display projection optics 21 as well as the beam splitter 8th one from the display 22 indicated fixation mark on the fundus 3 displayed.

2 shows an example of the striped distribution of the image area 23 in the image plane B1. In the middle of the picture area 23 is the illuminated strip 24 as an illustration of the slit diaphragm 14 of the lighting module 10 , At the top and bottom of the illuminated strip 24 there is an unlit area 28a respectively. 28b , The illuminated strip 24 corresponds in the example shown thus an angle of view in the horizontal direction of about 68 ° and an angle of view in the vertical direction of z. B. 30 °. Through the strip-like definition of the image field 23 For example, the artifacts caused by Purkinje reflections R3 and R4 may be in the unlit area 28a respectively. 28b be relocated. This avoids that the Purkinjereflexionen R3 and R4 affect the illuminated area of the fundus. The picture surface 23 is through the full circular area within the field stop of the eyepiece 6 established. The illuminated strip 24 For example, in the fundus camera 1 be stationary with respect to its main direction, ie it is not subject to translational movement. Appropriately, but can be a gap width change at the slit 14 be provided. As from the photographic representation according to 4 As can be seen, the artefacts of the third and fourth Purkinjereflexion R3 and R4 are in the range 28a such as 28b , The illuminated strip 24 is, however, thus free from reflections of the approximately point-like light source on the eye lens. Remaining reflections R5 and R6 have their origin in the eyepiece 6 ,

Another group of planes which are mapped into one another in the construction are the aperture planes A1 to A3. Aperture plane A1 is the pupil of the eye. In the aperture plane A2, the separation of the optical paths of the observation and illumination by the mirror 9 performed. The aperture plane A3 is the plane of the light source 11 with the LED module. The design of the aperture planes A1 to A3 primarily enables the masking of the artifacts of the first and second Purkinjereflexion R1 and R2, ie, the Purkinjereflexionen R1 and R2 are extinguished even before they on the image sensor 17 be imaged.

The mirror 9 makes a separation of the optical paths of observation and illumination, as in 3 is reproduced. numeral 25 in 3 marks the pupil, that is, the natural opening through which light enters the interior of the eye 2 can fall. The mirror 9 divides the area of the pupil 25 in a circular segment-shaped observation area 26 as well as one circular segmented lighting area 27 , In the lighting area 27 is the image of the approximately punctiform light source 11 , In the 3 are the two areas 26 and 27 for example, semicircular. As well, these two areas can also be formed circular section. Aperture of the pupil 25 according to 3 is preferably constant. The related aparative structure is fixed. Only the lens of the lens 18 the digital camera 16 can be moved to focus. This results in a particularly simple, cost-effective design of the fundus camera 1 ,

By means of the aperture evaluation according to 3 the first and second Purkinje reflection R1 and R2 are eliminated. The aperture plane A1 lies on the surface of the lens 4 in the region of the third Purkinjereflexion R3, so that there is a sharp image of the Purkinjereflexionen R3 and R4 and thus a limitation of the thereby impaired image area, as shown 4 is apparent. By aligning the structure such that the third and fourth Purkinjereflexionen R3 and R4 in the unused areas 28a such as 28b according to 2 can be imaged, the aforementioned reflections can be almost completely removed from the image. Because an approximately punctiform light source 11 is used and the resulting from the use of approximately point light source Purkinjereflexionen R3 and R4 in the areas 28a such as 28b In addition, by evaluating the position of the Purkinje reflection R3 and R4 in the image, it is additionally possible to deduce the relative position of the fundus camera to the eye. This results in the possibility of a, in particular automatic, centering of the fundus camera 1 on the eye 2 ,

The fundus camera according to the invention 1 allows the area of the fundus to be examined 3 thereby significantly enlarge the eye 2 in the previously described stationary, ie static structure of the illumination beam path and the detection beam path is guided guided, causing the area of the fundus 3 of the patient under the illuminated strip 24 the picture surface 23 shifts and the local area in the picture area 23 changed. This makes it possible to vertical areas of the fundus 3 from far more than 30 °. As a result, the possibility is created by simple means, extensive areas of the fundus 3 to submit to an investigation, which can be dispensed with the administration of pupil-dilated agents (Mydriatikum), which adjusts an increased patient comfort and no complex, provided with an adjustment mechanisms structures must be used.

The patient guidance module provided for such a patent administration 20 (see. 1 ) allows the generation of a fixation mark (light mask) on the fundus 3 in the image plane B1. By changing the fixation mark, the patient is prompted to adjust the eye position in comparison to the digital camera 16 to change according to the change in position of the fixation mark, for example by vertically up or down the fixation mark follows and thereby the area of the fundus to be examined 3 under the lighting strip 24 changed. In combination with a control of the patient guidance, the patient's line of vision can be controlled in such a way that different areas of the retina are imaged and these are combined by stitching into a larger overall picture. As a result, in the vertical direction, a range of 68 ° and more can be achieved. From the 5 is a highly simplified schematic representation of a corresponding created by patient guidance recording 33 in an extended angular range of the fundus 3 outlined. The recording 33 is from three single shots 33a - 33c built up to the recording 33 were assembled. On the picture visible blood vessels are with 34 characterized.

The 6 shows the principle of the patient guidance module 20 to enable focusing, ie adjustment of patient accommodation without moving parts. This is achieved by an inclination of the display 22 relative to the image plane B5. The variation of the fixation direction is by a vertical movement, ie a movement perpendicular to the plane of the 6 of the light spot or pixel serving as a fixation mark. The variation of the accommodation and the compensation of spherical refractive errors occurs in contrast by a horizontal movement, ie by a movement parallel to the plane of the 6 , Due to the tilt of the display 22 with respect to the image plane B5 changes with horizontal movement of the pixel (displacement of the pixel parallel to the plane of 6 ) the distance to the display projection optics 21 , A corresponding in 6 illustrated patient guidance module 20 is preferably provided for each eye, to vary the accommodation and to be able to compensate for any defective vision.

In the 7 illustrated embodiment of a fundus camera 1 with binocular patient guidance includes a patient guidance module 20 of the type described for each eye 2 as well as a microcontroller 29 indicating the movement of the fixation marks in the respective eye 2 associated patient guidance module 20 controls. A detection beam path between the eye 2 and the digital camera 16 is only in one eye 2 intended. The digital camera is connected via a suitable data line 32 , for example via an Ethernet Interface with a computer 31 in connection. Through a positioning unit 30 can the fundus camera 1 optimally aligned to the eyes. Preferably, the positioning unit is motorized and by the microcontroller 29 and the computer 31 automatically or manually controllable. As a basis for an automatic control, the position of the artifacts of the Purkinjereflexionen R3 or R4 in the image field 23 serve.

The entire structure of the fundus camera in 7 can be swiveled by 180 ° around an axis running between the two eyes (not shown), so that instead of the one eye, the other eye can also be examined.

In one-eyed patients, only the imaging part of the arrangement is used.

The microcontroller 29 also receives control commands from the computer 31 to the LEDs of the light source 11 turn on and turn off in the right order. At the same time, the computer 31 the digital camera 16 triggered so that illumination and exposure are synchronized. The digital camera 16 has inputs and outputs for communication and the transmission of control commands from the computer 31 to the microcontroller 29 to enable as well as to synchronize lighting and exposure. Alternatively, the computer can also work directly with the microcontroller 29 be connected. Into the digital camera 16 An autofocus unit can be integrated to compensate for spherical vision defects.

With the help of the software on the computer, sequentially acquired gray value images are combined into a single color image. Here it is necessary to detect any existing offset of the images (registration), compensate for this and then combine the images into a color image. The computer is equipped with a user interface, which allows the operation and control of the fundus camera and the display of the fundus images.

Photographic observation and / or documentation in the context of this invention includes static photographic images as well as film or video recordings.

LIST OF REFERENCE NUMBERS

1

fundus camera

2

eye

3

Fundus (fundus)

4

lens

5

Cornea

6

eyepiece

7

field lens

8th

beamsplitter

9

mirror

10

lighting module

11

light source

12

collimator

13

polarizing filter

14

slit

15

collimator

16

Digital camera

17

image sensor

18

lens

19

polarizing filter

20

Patient management module

21

Display projection optics

22

display

23

scene

24

illuminated strip

25

pupil

26

observation area

27

lighting area

28

unlit area

29

microcontrollers

30

positioning

31

computer

32

data line

33

admission

34

blood vessel

A1-A3

Aperturebenen

B1-B5

image planes

F1-F4

Origin of the first to fourth Purkinjereflexionen

R1-R4

First to fourth Purkinjerelexion

R5-R6

Reflections of the eyepiece

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2012/059236 A1 [0010]

Cited non-patent literature

• El-Bayadi, George: New Method of Slit-Lamp Micro-Ophthalmoscopy, In: Brit. J. Ophthal., Vol. 37, 1953, pp. 625-628 [0008]
• Higher, B .; [Et. Al.]: Non-mydriatic, 68 ° wide fundus imaging with low cost components. In: Abstract of the ARVO Annual Meeting 2012, May 2012 [0009]

Claims (17)

Fundus camera ( 1 ) for the photographic observation, documentation and / or diagnosis of the retina of an eye ( 2 ) comprising a lighting module ( 10 ) with limited light source ( 11 ) for generating an illumination beam path, an image plane (B3) in the illumination beam path for the production of photographic images, an image surface ( 23 ), the image of the fundus ( 3 ) on the image plane (B3), a digital camera ( 16 ), a detection beam path between the digital camera ( 16 ) and the fundus ( 3 ), Means for subdividing the detection beam path into a detectable observation area ( 26 ) and a non-detectable illumination area ( 27 ), wherein the illumination beam path and / or the detection beam path relative to the overall structure of the fundus camera ( 1 ) is stationary, characterized in that a slit diaphragm ( 14 ) for limiting the image area ( 23 ) on a lighted strip ( 24 ) of the fundus ( 3 ) next to unlit areas ( 28a . 28b ), as well as a patient guidance module ( 20 ) is provided, by means of which by targeted guidance of the line of sight of the patient to be examined area of the fundus ( 3 ) is changeable to the position of the illumination beam path and the detection beam path Fundus camera according to claim 1, characterized in that the detectable observation area ( 26 ) and the non-detectable illumination area ( 27 ) have a semicircular or circular section-shaped expression. Fundus camera according to claim 1 or 2, characterized in that the aperture plane (A1) in an area between the front of the cornea ( 5 ) and back of the lens ( 4 ) of the eye ( 2 ), preferably in the middle of the lens ( 4 ). Fundus camera according to one of claims 1 to 3, characterized in that an eyepiece ( 6 ) for mapping the fundus ( 3 ) to the intermediate image plane (B2) and a field lens ( 7 ) is provided for imaging the aperture plane (A1) on the aperture plane (A2), which lies on or in the region of the mirror surface. Fundus camera according to claim 1, characterized in that the patient guidance module ( 20 ) a display ( 22 ), the display ( 22 ) for producing a fixation mark for the eye ( 2 ) and the fixation mark of the display ( 22 ) on the fundus ( 3 ) of the eye ( 2 ) is displayed. Fundus camera according to claim 5, characterized in that the patient guidance module ( 20 ) an image plane (B5) and a display projection optics ( 21 ) and the display ( 22 ) has an oblique orientation relative to the image plane (B5). Fundus camera according to one of claims 1 to 6, characterized in that a variation of the viewing direction by relative movement of the fixation mark parallel to and / or a variation of the focus by a movement of the fixation mark perpendicular to the line of intersection between display ( 22 ) and focal plane (B5). Fundus camera according to one of claims 1 to 7, characterized in that in each eye ( 2 ) by an associated patient guidance module ( 20 ) a Fixatonsmarke is generated and the movement of the fixation marks via a microcontroller ( 29 ) for both eyes ( 2 ) is controlled. Fundus camera according to one of claims 1 to 8, characterized in that as light source ( 11 ) a multiple LED is provided consisting of several individual LEDs with different emission wavelengths, preferably a triple LED with three emission wavelengths from the ranges 600 nm to 1000 nm (red to infrared) or 520 nm to 565 nm (green) or 350 nm to 480 nm (blue to ultraviolet). Fundus camera according to one of claims 1 to 9, characterized in that as a digital camera ( 16 ) a digital black and white camera is provided. Fundus camera according to claim 1, characterized in that the illuminated area ( 24 ) of the image area ( 23 ) an angle of view in the transverse direction to the illuminated strip ( 24 ) of at most 5 ° -30 °, preferably 20 °. Fundus camera according to claim 1, characterized in that the illuminated strip ( 24 ) of the image area is an angle of view in the longitudinal direction of the illuminated strip ( 24 ) of 30 ° -80 °, preferably 68 °. Fundus camera according to claim 1, characterized in that by changing the line of sight of the eye ( 2 ) of the patient different areas of the fundus ( 3 ) in the form of individual photographs ( 33a - 33c ) separately detectable and to a recording ( 33 ) are joinable. Fundus camera according to claim 1, characterized in that a monocular or binocular eye guidance of the patient is provided by on the fundus ( 3 ) of an eye ( 2 ) or both eyes ( 2 ) a fixation mark is displayed. Fundus camera according to claim 1, characterized in that in the case of binocular eye guidance for the fixation markers of both eyes ( 2 ) a stereo image pair is usable. Fundus camera according to claim 1, characterized in that the fixation mark with spherical refractive error of the eye is sharply imaged on the retina. Fundus camera according to claim 1, characterized in that a targeted stimulation of the accommodation state, preferably a Deakkommodation is feasible.

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