HK1175978B - Ophthalmological analysis apparatus and method - Google Patents

Abstract

The invention relates to an ophthalmological analyzer (10) and an analysis method with such an analyzer, in particular for measuring a topography of a surface of an eye, with a projection device (11) and an observation device (12), wherein the projection device comprises at least one lighting device and a diaphragm device, wherein the illumination device comprises at least one first light source (25), wherein by means of the screening device, an image pattern on a surface of an eye (13) is mapped, wherein said observation device is a camera (36) and a lens (37), said images by means of the observation device the imaged pattern image can be recorded, wherein the images from a topography of the surface can be derived, wherein the lens means an enlargement of the image can be changed.

Description

The invention relates to an ophthalmological analytical apparatus with the characteristics of the generic term of claim 1 and an analytical method with the characteristics of the generic term of claim 5.

In the case of the most up-to-date analytical instruments and topography systems, a single-colour eye is regularly illuminated, for example by infrared light, to avoid glare to the extent possible. Topography systems are known to allow pupilometric measurements in addition to measuring the surface of the eye. In particular, when illuminating the eye with monochromatic light, only partially visible, a contraction of the pupil is effectively avoided, so that such illumination is particularly suitable for pupilometric measurements. Topographic lighting systems can also have several light sources to illuminate a single eye.

In order to make a statement about the quality of the tear film, a tear time is measured regularly. This measurement is also performed by illuminating the eye with infrared light. For example, a tear film measurement, in addition to the topography of the surface of the eye, is of great importance in a selection of contact lenses. Therefore, a tear film analysis is a further analysis of the distribution of tear film, for example, by limiting the range of possible methods of analysis and, if necessary, by improving the quality of the eye.

1 723 900 reveals a device and a method for evaluating the dry state of the eye by measuring the rate of movement of the tear fluid.

DE 10 2004 055 683 A1 describes an operating microscope in which, in particular, a projection device is placed in a beam tube of the microscope, enabling the image consisting of markings to be coupled to the beam tube in such a way that the image of an eye to be operated on which the viewer is looking is superimposed on the coupled image.

EP 0 697 611 A2 concerns an eye-operating microscope combined with an optical coherence tomography system, in particular a projection device for illuminating the eye to be operated on and a magnifying glass which enables an image of the eye to be magnified.

EP 2 016 888 A1 describes an ophthalmological analytical apparatus for topographic measurement, which essentially consists of a cone-shaped placidoid disc with a camera to capture a projected image pattern on one eye.

US 5.159.361 A1 concerns a topography system where a lens allows a variable magnification of a cornea.

The present invention is therefore intended to propose an ophthalmological analytical apparatus and an analytical method with an ophthalmological analytical apparatus, which will extend and improve the investigative capabilities of a topographic system.

This task is solved by a device with the characteristics of claim 1 and a process with the characteristics of claim 5.

The ophthalmological analytical apparatus of the invention, especially for measuring the topography of the surface of an eye, shall have a projection device and an observation device, the projection device comprising at least a lighting device and an aperture device, the lighting device comprising at least a primary light source, the aperture device capable of representing an image pattern on the surface of an eye, the observation device comprising a camera and a lens, the observation device capable of extracting images of the image pattern, the images capable of representing a topography of the surface, and the lens capable of enlarging the image.

The camera and lens of the observation device make it possible to use the images obtained in a high-quality manner, so that, depending on the type of measurement, it is possible to choose a magnification of the lens in such a way that the object or property to be measured is visually represented in such a way that it is possible to evaluate the image and obtain particularly accurate measurement results.

At very high magnification, it is possible to focus the tear film so that particles in the tear film, such as dust particles or foreign bodies, become visible. A possible movement of these particles can be traced and measured in terms of direction and speed. This can be derived from which direction or at what speed the tear film flows. This measurement can be used to determine the quality of a tear film even more precisely.

The lens can be equipped with a magnifying glass, which allows at least one lens to be inserted into or removed from a beam of the lens. Compared with a variable magnification setting, which is also conceivable, a magnifying glass is particularly easy and cost-effective to manufacture.

The lens can be used to make at least three magnifications, which are not in accordance with the invention, which are advantageous. A first normal magnification can be used to measure the topography of the eye's surface. A second large magnification can be used to measure or analyze a tear film. For example, a lipid layer can be focused on to determine its thickness, especially at low depths of focus. A third small magnification can be used especially for meibometric studies, since an image of meibom glands requires, among other things, an increased analysis of the distance of the instrument relative to the eye.

The first light source can also emit light in a predominantly monochromatic spectrum, so that the light from the first light source can be better detected by the observation device.

The first light source can be used to emit light in a predominantly infrared spectrum, which has a particularly low glare effect on the eye and is easy to obtain.

The lighting device may, in an embodiment not covered by the invention, have at least one additional light source capable of emitting polychromatic light in a predominantly visible spectrum. In addition to using essentially monochromatic light or light of a relatively narrow wavelength range, the additional light source may illuminate the surface of the eye with polychromatic visible light, which makes it possible to make additional measurements of eye properties and to obtain more accurate measurement results. Compared to monochromatic or infrared light, it will then be possible to determine a degree of redness of the eye with polychromatic light. Also, a thick film or other lip-layer of lip-film can be used to measure the surface of the eye with a high degree of accuracy, especially when the color of the light emitted is not particularly good, since it cannot be used to produce a very good measurement of the color of the white light, which is not particularly useful for producing a good color-imaging of the white light, especially when the color of the light emitted is not invasive.

In a non-invention, the additional light source may be composed of a large number of evenly distributed LEDs. For example, the LEDs themselves may produce the image pattern. The LEDs may be arranged in a ring shape or behind a lens that can project the image pattern onto the eye. The LEDs that produce the additional light source may be arranged at the lighting device together with the LEDs that produce the first light source.

It is particularly advantageous if, in an embodiment not covered by the invention, a pass in the aperture is formed in the aperture for a beam passage of the observation device in a direction not corresponding to the optical axis of the eye. The aperture may be made up of, for example, a luminous ring or a number of concentric rings of the pupil type to produce a placidobit pattern. If the aperture is formed along the optical axis of the eye with its measuring axis, the passing of the beam through the aperture may be made possible by means of direct or indirect measurement of the optical pattern, in particular by means of the aperture of the aperture.

The analytical apparatus may, in an embodiment not covered by the invention, also have a lens to produce a glare on the eye, the lens being a source of glare and a radiation divider to reflect the glare into the beam path of the observation device. The eye may be blinded by this lens while a reaction of the eye can be recorded by the observation device. For example, a movement of the pupil caused by glare can be detected and evaluated. The lens may be operated independently of the lighting device or the lighting patterns produced.

It is also possible to use the lighting device and/or the glare device to glare the eye to increase the production of tear fluid, thus verifying or measuring the formation of a tear film.

The method of analysis of the invention is performed with an ophthalmological analytical apparatus for measuring the topography of the surface of an eye, the analytical apparatus comprising a projection device and an observation device, the projection device comprising at least a lighting device and an aperture device, the aperture device imaging a pattern on the surface of the eye, the observation device imaging the imaged pattern, the images deriving a tear film flow, the motion of particles moving at a rate of motion on the surface of the surface.

At very large magnification, it is possible to focus the tear film so that particles in the tear film, such as dust particles or foreign bodies, become visible. A possible movement of these particles is then tracked and measured in terms of direction and speed. This can be derived from which direction or at what speed the tear film flows. This measurement is used to determine a tear film quality even more precisely.

In one embodiment of the process, the analytical apparatus may have an evaluation device by means of which the images are analysed. It is advantageous that the evaluation device may be located in the analysis device itself and allow for the processing of the images and a visualized output of the measurement results obtained by the evaluation device. The evaluation device may include in particular data processing devices which can then also perform digital processing of the images. It is also conceivable that the data processing devices may have data storage devices with a database, whereby the database may have comparative records of images or surface parameters. The evaluation device may also be able to display accurate comparison measurement data, for example by means of a visual comparison source, whereby simplified inferences of probable results or corrections of measurements of trimetric measurements can be made. An evaluation can be carried out in particular by using a photographic film with a light emitting spectrum which can be measured in a particular direction and then significantly increased by using a photographic film with a visible light emitting spectrum, or a photographic film with a visible light emitting spectrum.

The images can also be used to determine the degree of redness of the eye, whereby a rotation ratio in a region of the eye can be measured. Such a measurement cannot be performed with infrared light or monochromatic light due to the lack of color reproduction.

The measurement of tear film rupture time is possible at normal magnification and can be performed under infrared or visible light. The image patterns projected onto the surface of the eye, such as placid rings, allow a tear film rupture to be detected, in particular by changing the image pattern.

The images further indicate a lipid layer on the tear film, which can be measured by interference colors. A lipid layer is the outer layer of the tear film, followed by a middle layer of water and an inner layer adjacent to the cornea (the muslin layer). The lipid layer is about 100 nm thick, prevents rapid evaporation of the aqueous layer and is formed by a secret of the meibomian glands. Since the lipid layer is a very thin layer of the tear film, these layers can be very easily measured by means of interference film.

This makes it possible to determine lipid layer thickness or thickness distribution and thickness and to study the function of the meioboma glands by measuring the amount of lipids, preferably by a large magnification.

Other advantageous embodiments of the process are shown by the characteristics of the subclaims derived from device claim 1.

A preferred embodiment of the invention is described below with reference to the accompanying drawings.

It shows: Figure 1: A simplified schematic cross-sectional view of an embodiment of an analytical apparatus; Figure 2: a front view of the analytical apparatus.

An overview of Figures 1 and 2 shows an embodiment of an analytical apparatus 10, which consists essentially of a projection device 11 and an observation device 12 for observing an eye 13; the analytical apparatus 10 also includes an evaluation device 14 with data processing and output means not described here and a positioning device 15 for positioning the analytical apparatus 10 relative to the eye 13 in three spatial directions with the vertical directional components x, y, z, as indicated here by the symbol.

The projection device 11 is formed as a hollow sphere segment 18 and comprises a grid aperture 19 and a reflector 20 which are arranged in a schematically indicated housing 21 such that the reflector 20 with a reflecting surface 22 is always at the same distance a from a surface 23 of the reflector 20 and thus a curved aperture 24 is formed. The surface 23 of the reflector 20 is highly reflective so that the aperture 24 is uniformly lit when a primary light source 25 or a further reflecting light source 26 is switched on. The light sources 25 and 26 are each of luminous density 27 or 28 pixels, which are arranged in equal proportions in a grid of 29 to 25 pixels, and the aperture 23 is arranged in a pattern of 23 to 35 pixels, each of which is arranged in a transparent grid of 19 to 35 pixels. The image is arranged in a grid of 32 to 35 pixels, each of which is arranged in a number of equal angles in the direction of the aperture.

The observation device 12 has a camera 36 with a lens 37 whereby the camera 36 includes, among other things, an optical video sensor 38 directly connected to the evaluation device 14. The lens 37 is composed of two lenses 39 and 40, with, in addition, as indicated here by the double arrow, a magnifying device 41 by means of which further lenses 42 can be inserted into a beam 43 of the observation device 12. This makes it possible to view the eye 13 in at least three different magnifications and angles. In the beam 43 the projection device 11 and the lens 37 are connected by means of a source of radiation 44 of a brightness, which consists of 45 A, but without a special measuring system, such a magnification can be determined by means of a numerical method. A beam 13 cannot be projected independently of the projection device 13 and can also be projected in the direction of the brightness.

As regards the operation of the analytical apparatus 10, it is envisaged that the light sources 27 may be used to illuminate the eye 13 as required. In particular, for determining the topography of the eye 13, it is sufficient to use the first light source 25 at a normal magnification of the lens source 37 whereas the first light source 25 is also used for further measurements of the light intensity of the lens 37 and a small magnification of the lens 37 is then used for a large-scale analysis, in particular for measuring the size of the lens 37 and the size of the lens 37 and a large-scale analysis of the lens 37 is then carried out.

Claims (11)

1. An ophthalmological analysis instrument (10), in particular for measuring a topography of a surface of an eye, having a projection apparatus (11) and a monitoring apparatus (12), the projection apparatus comprising at least one illumination device and an aperture device (19), the illumination device having at least one first light source (25), it being possible to image an image pattern (35) on a surface of an eye (13) by means of the aperture device, the monitoring apparatus having a camera (36) and an objective lens (37), images of the imaged image pattern being recordable by means of the monitoring apparatus, and a topography of the surface being derivable from the images, characterized in that a magnification of the image can be varied by means of the objective lens in such a manner that particles situated in the tear film become visible at high magnification.
2. The analysis instrument according to claim 1, characterized in that the objective lens (37) has a magnification changer (41), by means of which the at least one lens (42) can be introduced into a beam path (43) of the objective lens and removed therefrom.
3. The analysis instrument according to claim 1 or 2, characterized in that the first light source (25) can emit light in a predominantly monochromatic spectrum.
4. The analysis instrument according to claim 3, characterized in that the first light source (25) can emit light in a predominantly infrared spectrum.
5. An analysis method using an ophthalmological analysis instrument (10) for measuring a topography of a surface of an eye, said analysis instrument having a projection apparatus (11) and a monitoring apparatus (12), the projection apparatus comprising at least one illumination device and an aperture device (19), it being possible to image an image pattern (35) onto the surface of the eye (13) by means of the aperture device, images of the imaged image pattern being recorded by means of the monitoring apparatus, characterized in that a tear film flow is derived from the images, a speed of movement of particles situated on the surface being measured.
6. The analysis method according to claim 5, characterized in that the analysis instrument (10) has an evaluation apparatus (14), by means of which the images are analyzed.
7. The analysis method according to claim 5 or 6, characterized in that the illumination device has at least one light source (26) that emits polychromatic light in a predominantly visible spectrum, a tear film on the surface being determined from the images.
8. The analysis method according to claim 7, characterized in that a degree of reddening of the eye (13) is determined from the images, a proportion of red in a region of the eye being measured.
9. The analysis method according to one of claims 5 to 8, characterized in that a tear film break-up time is derived from the images, a change to the tear film being measured.
10. The analysis method according to one of claims 5 to 9, characterized in that a lipid layer on the tear film is determined from the images, the lipid layer being measured by interference colors.
11. The analysis method according to claim 10, characterized in that a lipid layer thickness is measured.