OPHTHALMOSCOPE FOR EXAMINING EYES

Abstract

An ophthalmoscope for examining eyes, includes: a housing; a converting device for converting light into an electrical signal; and an objective, the objective comprising a lens and/or a mirror. The objective has a convexly curved focus area, a convexly curved image surface of an eye being able to be sharply imaged onto the converting device by means of the objective.

Claims

1. An ophthalmoscope for examining eyes, comprising a housing, at least one device for conversion for converting light into an electrical signal, and at least one objective, wherein the at least one objective comprises at least one lens and/or at least one mirror, wherein the at least one objective having a convexly curved focus surface, wherein a convexly curved image surface of an eye being able to be sharply imaged onto the at least one device for conversion by means of the at least one objective, the entire visible area of the eye can be sharply imaged on the at least one device for conversion and a lens arrangement which has a negative Petzval sum is provided to image the convexly curved image surface of the eye.

2. The ophthalmoscope according to claim 1, wherein the at least one device for conversion is provided in the form of a planar chip or the at least one device for conversion comprises at least one Bayer filter.

3. The ophthalmoscope according to claim 1, wherein at least two lenses are formed in the shape of at least one air lens, wherein a Petzval sum of the at least one air lens is negative or a gas mixture with a refractive index smaller than 1.3 is arranged within the at least one air lens, wherein the gas mixture contains at least one noble gas, nitrogen or air.

4. The ophthalmoscope according to claim 1, wherein a lens-shaped fluid confinement is arranged between a sensor-sided lens and an object-sided lens, wherein the Petzval sum of the sensor-sided lens, the object-sided lens and the fluid confinement is negative.

5. The ophthalmoscope according to claim 3, wherein the at least one air lens is designed such that a lens with a first refractive index is arranged on the object side, and a lens with a second refractive index is arranged on the sensor side, wherein the second refractive index is higher than the first refractive index, or the at least one air lens is designed in a biconvex manner or exactly two spaced-apart air lenses are present.

6. The ophthalmoscope according to claim 1, wherein the at least one objective or an object-sided image or an object-sided ray path is designed to be essentially telecentric or pericentric, or an image on the at least one device for conversion is shown in color, or a sensor-sided numerical aperture of the at least one objective lies in the range from 0.04 to 0.1, or the at least one objective has an aperture, wherein the aperture has a radius in the range of 2.5 mm to 3.5 mm, or the ophthalmoscope comprises exactly eight lenses or exactly two planar discs, or at least one lens is designed to be aspherical, or at least one illuminated dot reticle is arranged in the at least one objective, centrally located on an optical axis of the at least one objective, or the at least one illuminated dot reticle comprises at least one diffractive structure, wherein the at least one diffractive structure has an extent in the range from 25 μm to 75 μm, or the at least one illuminated dot reticle is covered on the sensor side by a mask, or the housing comprises at least one peripheral cylinder, wherein the at least one peripheral cylinder is designed blackened in the portion of the at least one illuminated dot reticle.

7. The ophthalmoscope according to claim 6, wherein the light of the eye can be transmitted in chronological order through an objective lens, the illuminated spot reticle, a meniscus lens, an object-sided air lens, an object-sided diverging lens, the aperture, a converging lens, an achromat, a sensor-sided meniscus lens, a sensor-sided diverging lens, and a protective glass, wherein the light of the eye can subsequently be impinged upon the at least one device for conversion, or the object lens or the object-sided meniscus lens or the achromat comprise flint glass, or the converging lens or the achromat comprise crown glass.

8. The ophthalmoscope according to claim 1, wherein at least one holding device for a head is provided , the holding device has a chin rest or a forehead support or is spaced from the at least one device for conversion in the range from 30 mm to 200 mm.

9. The ophthalmoscope according to claim 1, wherein the at least one device for conversion can be brought into data connection with at least one computer, wherein the at least one computer (34) can be brought into connection with a database.

10. The ophthalmoscope according to claim 1, wherein at least one illumination is arranged on the housing, wherein the illumination of the eye via the at least one illumination is partially covered by the at least one objective, or the at least one illumination is designed in the form of a white light illumination with a sunlight-like white tone with a characteristic color temperature between 5000 K and 6000 K or a color rendering index of at least 95% or a fluorescent illumination, or the fluorescent illumination has a wavelength range between 450 nm and 510 nm or between 750 nm and 780 nm, or at least one fluorescence filter is arranged between the at least one device for conversion and the eye, or the ophthalmoscope comprises at least one status screen, wherein at least one electronic information can be visualized on the at least one status screen.

11. The ophthalmoscope according to claim 1 with a slit lamp.

12. A method for examining eyes, comprising the following steps: rough adjustment of a patient in a holding device, in particular with an accuracy below 3 mm, detection of a pupil and/or a vertex of a cornea of the eye via an image processing program, wherein it is particularly provided that the image processing program comprises an autofocus algorithm, capturing at least one image of the eye by an ophthalmoscope according to claim 1, wherein the at least one image of the eye is captured on at least one device for conversion.

13. The method according to claim 12, wherein movements of the eye below 3 mm are tracked by automated tracking, or an opening of an eyelid is detected via the image processing program, wherein when an opening is below 12 mm an indication is displayed on at least one status screen, or the at least one image of the eye on the at least one device for conversion is read into or saved at at least one computer in a database on the at least one computer, or the at least one image of the eye is evaluated or analyzed with regard to eye-specific characteristics, or the at least one image of the eye is categorized at the at least one computer for standardization or norming, or the eye comprises a contact lens and a tear fluid enriched with fluorescent dye, wherein the tear fluid is illuminated with fluorescent illumination, the tear fluid emits light in a wavelength range between 515 nm and 530 nm or between 825 nm and 835 nm, and a distribution of the emitted light of the tear fluid between the contact lens and the eye is recorded on the at least one device for conversion, or the eye comprises at least one fluorescent dye and a blood vessel structure or a lymphatic vessel structure or a corneal epithelium of the eye is imaged on the at least one device for conversion or saved on the at least one computer, or the fluorescent dye comprises fluorescein or indicyanine green, or after a period of at least one day, the method is carried out again.

14. A computer program product comprising commands, which, when carried out by a computing unit, cause the computing unit to classify, for an ophthalmoscope for examining eyes, at least one image of an eye from a memory unit, which is or can be brought in data connection with the computing unit, wherein a classification is generated, based on a blood vessel structure or a corneal structure or a scar structure or an eye socket structure.

15. The computer program product according to claim 14, wherein an image overlay with automatic blood vessel detection or automatic limbus detection can be used to control the classification or a semi-automatic lesion detection and/or bidirectional measurements can be carried out.

16. The computer program product according to claim 14, wherein standardized images of at least one iris are saved in the memory unit.

17. The computer program product according to claim 14, wherein a color of a contact lens or an artificial iris is selected depending on a color of two iris, wherein the color of the contact lens or the artificial iris is matched to one of the two iris.

18. The computer program product according to claim 14, wherein the blood vessel structure is automatically detected or a quantification of changes in the blood vessel structure or the corneal structure is calculated via the image overlay.

19. The computer program product according to claim 14, wherein a red pixel density measurement is carried out, wherein the red pixel measurement integrates a total red portion of the at least one image, or calculates an area portion of the blood vessel structure at the at least one image.

20. The computer program product according to claim 14, wherein an automatic lesion detection of the eye is comprised, or an opening of the eye of at least 12 mm is detected and when the opening is less than 12 mm an electronic information is transmitted to the at least one status screen.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0150] Further details and advantages of the present invention are explained in more detail below by means of the figure description with reference to the embodiments shown in the figures. Therein, they show:

[0151] FIGS. 1a-1c show an ophthalmoscope according to a preferable embodiment with a holding device,

[0152] FIGS. 2a-2c show the ophthalmoscope according to the embodiment shown in FIGS. 1a-1c with a slit lamp,

[0153] FIGS. 3a-3d show ray paths of light between an eye and a device for conversion, and the ray paths pass through an objective,

[0154] FIG. 4 shows an objective with an illumination in the direction of an eye in a schematically indicated view from the side,

[0155] FIG. 5 shows the ophthalmoscope according to the embodiment shown in FIG. 1a in data connection with a computer and a flow chart,

[0156] FIG. 6a shows an image not according to the invention of a concave geometry through a lens with a depicted correlation between a focus surface, an image surface, an object-sided image, and an image,

[0157] FIG. 6b shows an objective of an ophthalmoscope with three mirrors during capturing an image of an eye onto a device for conversion,

[0158] FIGS. 7a-7b shows a blood vessel structure in an image of a human eye, and a blood vessel structure, identified by a computer program product, using the image of the eye.

DETAILED DESCRIPTION OF THE INVENTION

[0159] FIG. 1a shows an ophthalmoscope 1 for examining eyes 2 comprising a housing 3 and a device for conversion 4 of light into an electrical signal (not visible in the illustration).

[0160] A holding device 31 for a head 32 is provided, and a chin rest 33 and a forehead support 45 are arranged on the holding device 31. The head 32 is aligned to the ophthalmoscope 1 by the holding device 31 and the chin rest 33 as well as the forehead support 45 in such a way that the eye 2 is positioned stationary for at least one image 16 by the ophthalmoscope 1.

[0161] The holding device 31 is spaced from the at least one device for conversion 4 between 30 mm and 200 mm, and the spacing can be adjusted by an operator of the ophthalmoscope 1.

[0162] The ophthalmoscope 1 is used on the human eye 2.

[0163] FIG. 1b shows the ophthalmoscope 1 according to FIG. 1a pivoted about a vertical axis by 90 degrees in one direction. FIG. 1c shows the ophthalmoscope 1 according to FIG. 1a pivoted about a vertical axis by 90 degrees in the opposite direction.

[0164] FIG. 2a shows the ophthalmoscope 1 according to FIG. 1a with a slit lamp 36.

[0165] An image 16 on the at least one device for conversion 4 can be displayed in color. A sensor-sided numerical aperture of the objective 5 lies in the range of 0.04 to 0.1. The objective 5 has an aperture, and the aperture has a radius in the range of 2.5 mm to 3.5 mm during imaging the eye 2 by the ophthalmoscope 1 (not shown for clarity reasons).

[0166] The objective can also have an object-sided numerical aperture, preferably in the range of 0.04 and 0.1.

[0167] FIG. 2b shows the ophthalmoscope 1 according to FIG. 2a pivoted 180 degrees about a vertical axis. FIG. 2c shows the ophthalmoscope 1 according to FIG. 2a in a perspective view from the front.

[0168] Where the eye 2 has a contact lens and a tear fluid enriched with fluorescein dye as a fluorescent dye, in which the tear fluid is illuminated with a fluorescent illumination 35, the tear fluid can emit light in a wavelength range between 515 nm and 530 nm, and a distribution of the emitted light of the tear fluid between the contact lens and the eye 2 is recorded on the at least one device for conversion 4. If the fluorescent dye is indocyanine green, the emitted light has a wavelength in the range of 825 nm to 835 nm.

[0169] If the eye 2 comprises at least one fluorescent dye, a blood vessel structure 46 and/or a lymph vessel structure and/or a corneal epithelium of the eye 2 can be imaged on the at least one device for conversion 4. Particularly preferable hereby is the use of a fluorescence filter 43 (not shown for reasons of clarity). The image 16 can subsequently be saved on a computer 34.

[0170] The ophthalmoscope 1 comprises a status screen 44, in which electronic information is visualized on the status screen 44.

[0171] The images 16 can be repeated after a desired interval.

[0172] FIG. 3a shows a sectional view of a surface geometry of an eye 2, an objective 5, and a device for conversion 4. The device for conversion 4 is formed in the form of a planar chip 9, and the chip 9 is formed as a CMOS sensor 10. The CMOS sensor 10 comprises a Bayer filter 11 (not shown for clarity reasons).

[0173] The objective 5 comprises eight lenses 6 and two planar discs 20. The lenses 6 are formed spherical, but can generally also be formed aspherical.

[0174] A ray path 17 of light, starting from the surface geometry of the eye 2, impinges on the CMOS sensor 10 after a transmission through the objective 5. The light of the eye 2 is transmitted in chronological order through an objective lens 26, an illuminated dot reticle 21, a meniscus lens 27, an object-sided air lens 6, an object-sided diverging lens 28, an aperture, a converging lens 29, an achromat 30, a sensor-sided meniscus lens 27, a sensor-sided diverging lens 28, and a protective glass.

[0175] Two such ray paths 17 are shown in the illustration, in which—starting from the eye 2—the upper ray path 17 starts from a more curved portion of the surface geometry of the eye 2, and the lower ray path 17 starts from a less curved portion of the surface geometry of the eye 2. Due to the transmission through the eight lenses 6, the upper ray path impinges on a lower portion, and the lower ray path impinges on an upper portion relative to the lower portion of the CMOS sensor 10.

[0176] One planar disc 20 comprises the illuminated dot reticle 21, and the second planar disc 20 acts as a protective glass for the device for conversion 4.

[0177] Four lenses 6 are formed in the shape of two air lenses 12 spaced apart from each other, and a Petzval sum of the two air lenses 12 is negative. The two air lenses are formed in a biconvex manner.

[0178] The two air lenses 12 each comprise a lens-shaped fluid confinement 15, and the lens-shaped fluid confinement 15 is arranged between a sensor-sided lens 6 and an object-sided lens 6. The Petzval sum of the sensor-sided lens 6, the object-sided lens 6, and the fluid confinement 15 is negative.

[0179] The air lens 12 is designed in such a way that a lens 6 with a first refractive index is arranged on the object side, and a lens 6 with a second refractive index is arranged on the sensor side, and the second refractive index is higher than the first refractive index.

[0180] FIG. 3b shows the eye 2, the objective 5 as well as the device for conversion 4 according to the embodiment example shown in FIG. 3a, in which to the upper and lower ray path 17 in each case two further ray paths 17 are shown, which each have a smaller or larger aperture angle to a longitudinal alignment of the objective 5. Despite the different aperture angles, identical points on the surface geometry of the eye 2 meet identical points on the CMOS sensor 10 after transmission through the objective 5.

[0181] As ray paths 17 of equal points of the eye 2 of different aperture angles are projected onto equal points on the device for conversion 4, this results in a sharp image 16 of the eye 2 on the device for conversion 4, and the sharp image 16 is not limited to an annular zone of the eye 2.

[0182] The reason for the sharp image 16 of the eye 2 on the CMOS sensor 10 is a convexly curved focus surface 7 (not shown for clarity reasons) of the objective 5. A convexly curved image surface 8, which, without the objective 5, would correspond to the convexly curved surface geometry of the eye 2, is sharply imaged onto the device for conversion 4 by the objective 5 with the convexly curved focus surface 7. A sharp image 16 of the eye 2 on the CMOS sensor 10 is the result of this constructive design of the objective 5.

[0183] FIG. 3c shows the objective 5 according to FIG. 3a, in which different ray paths 17, starting from a point on the surface of the eye 2, which are each imaged by the objective 5 onto the same point on the CMOS sensor 10. A blurred image 16 is thereby prevented.

[0184] The object lens 26, the object-sided meniscus lens 27, and the achromat 30 comprise flint glass. The converging lens 29 and the achromat 30 comprise crown glass.

[0185] The objective 5 can also comprise one or more mirrors 42 (not visible in the illustration) to direct the ray paths 17 particularly favorably to the CMOS sensor 10 and to improve a sharp image 16 of the eye 2.

[0186] A fluorescence filter 43 is arranged between the at least one device for conversion 4 and the eye 2.

[0187] The fluorescence filter is particularly preferably placed in the focus of one of the lenses 6.

[0188] A pupil aperture can be located between the diverging lens 28 and the converging lens 29.

[0189] FIG. 3d shows the objective 5 according to FIG. 3a, in which it is visible that the objective 5 and an object-sided image 16a (not shown for clarity reasons) and an object-sided ray path 17 are essentially formed telecentrically. The objective 5, the object-sided image 16 and the object-sided ray path 17 can also be formed pericentrically.

[0190] In order to fix over an alignment of the eye 2 over a longer period of time relative to the objective 5, the illuminated dot reticle 21 is arranged in the at least one objective 5, centrally located on an optical axis 22 of the at least one objective 5. This also allows for a norming of the images 16 of the eye 2, as the alignment of the eye 2 can be directed again to the desired position after an interruption of images by the ophthalmoscope 1.

[0191] The illuminated dot reticle 21 comprises a diffractive structure 23, in which the diffractive structure 23 has an extension in the range of 25 μm to 75 μm. The illuminated dot reticle 21 is covered on the sensor side by a mask 24 (not shown for clarity reasons) so as not to interfere with the image 16 of the eye 2 on the device for conversion 4. The diffractive structure 23 can be illuminated laterally with an LED of any color, and the light from the LED is redirected towards the eye.

[0192] An optical length of the ray paths is equal. To achieve this, an optical density is increased at the periphery, and decreased at the center. This compensation can be generated by biconvex air lenses 12.

[0193] The objective 5 is constructively designed in such a way that an optical transmission is homogeneous and particularly high over the entire field.

[0194] FIG. 4 shows an objective 5, in which the housing 3 comprises a peripheral cylinder 25. The peripheral cylinder 25 is formed in a blackened manner. It can also be provided that the peripheral cylinder 25 is formed in a blackened manner only in a portion of the illuminated dot reticle 21.

[0195] An illumination 35 is arranged on the housing 3, in which the illumination of the eye 2 via the illumination 35 is covered partially by the objective 5. In general, the shape of the illumination 35 is arbitrary. Particularly preferable is an illumination 35 which is arranged annularly around the housing 3. However, several illuminations 35 can also be arranged on the housing 3, or an illumination 35 in the form of a commercial lamp can be used.

[0196] That illumination of the eye 2 which is covered by the objective 5 would result in unwanted reflections on the device for conversion 4, which would additionally result in unwanted overexposure of portions of the eye 2. In addition, the covered portion of the illumination can reduce pupil dilation and/or pain sensation. Central portions of a cornea are thus not illuminated directly, but this portion of the illumination is deflected or shadowed.

[0197] The illumination 35 is designed such that the light of the illumination 35, which is diffusely scattered upon penetrating the cornea and a sclera, contributes to the image 16.

[0198] The light of the illumination 35 increases in the direction of an outer region of the eye 2 in order to generate a homogeneous brightness distribution on the device for conversion 4.

[0199] The illumination 35 can be present in the form of white light illumination, for instance with a sunlight-like white tone with a characteristic color temperature between 5000 K and 6000 K and/or a color rendering index of at least 95%. The illumination 35 can comprise polychromatic light. The illumination 35 can also be designed as a fluorescent illumination, for instance with a wavelength range between 450 nm and 510 nm and/or between 750 nm and 780 nm.

[0200] FIG. 5 shows an ophthalmoscope 1, wherein the device for conversion 4 of the ophthalmoscope 1 is in direct data communication with a computer 34. The computer 34 is in signal-transmitting data connection with a database on a remote computer. However, the database can also be present directly on the computer 34.

[0201] A flowchart describes a method for examining eyes 2, comprising the following steps: [0202] rough adjustment of a patient in a holding device 31, in which an accuracy of the rough adjustment below 3 mm is particularly advantageous for sharp images of the eye 2 on the device for conversion 4, [0203] recognition of a pupil and/or a vertex of a cornea of the eye 2 via an image processing program, and the image processing program can comprise an autofocus algorithm to support the recognition, and [0204] capturing at least one image 16 of the eye 2 by the ophthalmoscope 1, in which the at least one image 16 of the eye 2 is captured on the device for conversion 4.

[0205] In addition, further steps are being provided according to this shown embodiment of the method: [0206] movements of the eye 2 below 3 mm can be tracked by automated tracking and/or an opening of an eyelid can be detected via the image processing program—when the opening of the eye 2 is at least 12 mm, preferably at least 16 mm, an indication can be displayed on a status screen 44, [0207] the at least one image 16 of the eye 2 on the device for conversion 4 is read into the computer 34 and saved, [0208] the at least one image 16 of the eye 2 is evaluated and analyzed regarding eye-specific characteristics, and [0209] the at least one image 16 of the eye 2 is categorized at the computer 34 for standardization and norming.

[0210] A computer program product is provided at the computer 34, which comprises commands that, when carried out by a computing unit 40, cause the computing unit 40 to do the following for an ophthalmoscope 1 for examining eyes 2: [0211] to classify the at least one image 16 of the eye 2 from a storage unit 41, which is in a data connection with the computing unit 40, and a classification is generated based on a blood vessel structure 46 or a corneal structure or a scar structure or an eye socket structure, [0212] in which an image overlay with automatic blood vessel detection or automatic limbus detection is used to control the classification [0213] in which a semi-automatic lesion detection or bidirectional measurements are carried out, and [0214] in which standardized images 16 of at least one iris are saved in the memory unit 41.

[0215] The computer program product can also select a color of a contact lens and an artificial iris depending on a color of two iris, and the color of the contact lens and the artificial iris is matched to one of the two iris.

[0216] In addition, the computer program product can automatically detect the blood vessel structure 46, and hereby using, for instance, artificial intelligence. A quantification of changes in the blood vessel structure 46 and/or the corneal structure can also be calculated via the image overlay.

[0217] In addition, it is possible to perform a red pixel density measurement, and the red pixel measurement integrates a total red portion of the at least one image 16, and/or calculates an area portion of the blood vessel structure 46 on the at least one image 16.

[0218] The computer program product comprises an automatic lesion detection of the eye 2, and can detect an opening of the eye 2 of at least 12 mm. With an opening of less than 12 mm, an electronic information is transmitted to the at least one status screen 44 of the ophthalmoscope 1.

[0219] The ophthalmoscope 1 can be used in a stand-alone embodiment or as an add-on embodiment for a commercial slit lamp 36.

[0220] FIG. 6a shows a concavely curved object with a concavely curved object surface and a device for conversion 4. Ray paths 17 visualize the transmission of light through a lens 6, starting from the concavely curved object in the direction of the device for conversion 4.

[0221] Without lens 6, the concavely curved object surface would be imaged onto a concavely curved image surface 8 (indicated by a dashed line). The lens 6 enables an image 16 on a planar device for conversion 4, in which the image surface 8 is also designed to be planar (indicated by a dashed line). The concavely curved image surface 8 can thus be sharply imaged onto the device for conversion 4 through the lens 6. With a convexly curved object, a convexity would be further enhanced by this lens 6, making a sharp image 16 onto the planar device for conversion 4 impossible.

[0222] The focus surface 7 is defined to the right of the lens 6, and in the illustration, the focus surface 7 is indicated by a dashed line in the image plane. The focus surface 7 is designed to be concave, and a convex focus surface 7 is provided according to the invention.

[0223] FIG. 6b shows ray paths 17 between an eye 2 and a device for conversion 4. The ray paths 17 are redirected to the device for conversion by three mirrors 42.

[0224] The mirrors 42 are hereby designed as free-form mirrors. However, the mirrors 42 can also comprise other types of mirrors.

[0225] The objective 5 of the ophthalmoscope has a curved focus surface 7 (not shown for clarity reasons) in order that the eye 2 can be sharply imaged on the device for conversion 4.

[0226] Using the objective 5 on the eye 2 in combination with at least one lens 6 is also possible.

[0227] FIG. 7a shows an image 16 of a human eye 2. A blood vessel structure 46 can be detected, in which the blood vessel structure 46 can be identified by a reddish color.

[0228] FIG. 7b shows a blood vessel structure 46, which is generated over the image 16 of the eye 2 shown in FIG. 7a by the computer program product using the automatic blood vessel detection.

[0229] Based on the blood vessel structure 46, an analysis, a categorization and/or a red pixel density measurement of the image 16 of the eye can be performed.