DE212007000086U1 - Ophthalmological device for determining a position of an eye of a patient - Google Patents

Abstract

Ophthalmological apparatus for optical and photometric examinations on an eye (2) of a patient, comprising an observation device (3) for observing an eye part (4, 400) to be examined, in particular an ocular fundus (4, 400) in a prescribable recording position (5) of the eye Eye (2), and a measuring device (6) with a measuring sensor (61) for determining a position (50) and / or an orientation (51) of the eye (2) with respect to the observation device (3), characterized in that an intensity and / or a direction of a measuring signal (8, 8a, 8b) reflected on a surface (7, 70, 700), in particular on the cornea (7, 70) of the eye (2), can be measured with the measuring sensor (61) in that the position (50) and / or the orientation (51) of the eye (2) with respect to the observation device (3) can be determined automatically with the aid of the measuring sensor (61).

Description

The The invention relates to an ophthalmological device for optical and photometric examinations on an eye of a patient with respect to an observer of an ophthalmic device according to the preamble of the independent claim 1.

Known ophthalmic devices have the disadvantage, among other things, that repeated, successive examinations and measurements make it almost impossible for the physician to always use the device exactly the same with respect to the center of curvature of the cornea front surface or the visual axis of the patient's eye to align reproducibly. However, this is necessary if examination values from time-staggered examinations are to be comparable. As an example of such a device is on the CH 662 261 directed. For an eye examination with such a device, the head of a patient is fixed on a fixation device. In turn, the patient fixes the eye to be examined by directing it to a fixation mark inserted in the beam path of the microscope. The device which can be adjusted in the direction of the three spatial axes is set by the observer, ie by the ophthalmologist or the optician relative to the patient's eye, in such a way that he perceives a sharp image of the fundus or of his body to be examined. The observer, however, lacks the possibility, in later investigations, of setting up the device on the same observation axis as in the preceding one. As a result, other light reflections result in subsequent examinations, among other things, than in the preceding ones, which falsifies the brightness measurement at the examined eye fundus site and renders the measured values useless for lack of reproducibility. One of the main reasons for the poor reproducibility of the measurement is that a light signal required for carrying out the adjustment must run through the eye through the eye to the back of the eye and back to the observer.

A significant improvement in comparison was therefore some time ago in the EP-A-0 608 516 which teaches an optical device with which it is possible to reproducibly position the optics of a microscope or a camera for imaging the retina in relation to a patient's eye.

Either the distance between the eye and the optics, as well as the optical Axes (direction) can be positioned exactly, so that a precise repositioning is possible. In this process a cone of light is irradiated to the cornea, with the apex of the cone is in the eye. Because the surface of the cornea is spherical is, a part of the light - if the distance is right - than Beam with constant cross-section mirrored back. If the Distance is too short or too long, expands or narrows the reflected light beam. Does not meet the optical axis to the center the cornea, then the direction in which it reflects changes Light is thrown back. If the optical system is accurate and repeatedly positioned in front of the eye leaves the light reflected from the blood vessels of the retina evaluate quantitatively and reproducibly, for example to a Determination of blood values.

Instead of such a method in humans for reproducible positioning It can also be used on pets, for example become. Thus, in the context of this application under patient also Pet or another creature with biologically comparable Eyes are understood.

For a better understanding of the present invention, the prior art will be described in more detail below with reference to the 1 and 2 which schematically illustrates an ophthalmological device or a field of view with eyepiece according to FIG EP-A-0 608 516 demonstrate.

The device of EP-A 0 608 516 according to 1 used for optical or photometric examination on a patient's eye 23 ' , It has a lighting device 11 ' . 12 ' . 13 ' and an observation device 1' . 2 ' . 3 ' . 9 ' for the fundus. In order to be able to align the optical axis of the observation device always on the same from the center of curvature of the Corneavorderfläche outgoing radial beam, is the observation device 1' . 2 ' . 3 ' . 9 ' a positive conversion lens 20 ' prefixed. This generates in an intermediate image plane 16 ' in the area of her the patient's eye 23 ' averted focal plane a real intermediate image of the eye to be examined for the observation device 1' . 2 ' . 3 ' . 9 ' , Next is on the conversion lens 20 ' averted side of the intermediate image plane 16 ' near or on the optical axis a glowing mark 22 ' available. The mentioned elements 1' . 2 ' . 3 ' . 9 '; 20 '; 11 ' . 12 ' . 13 ' are in their entirety by an operator of the device so in front of the patient's eye 23 ' Alignable and centerable, that at the same time in the intermediate image plane 16 ' a sharp image of the eye part to be examined or the section of the retina to be examined is formed and at a defined, in the observation device 1' . 2 ' . 3 ' . 9 ' visible location of the intermediate image plane 16 ' using the anterior surface of the cornea of the patient's eye 23 ' in the sense of a spherical mirror, a sharp image of the shining brand 27 ' appears.

The device has a horizontally arranged 10 to 20-fold magnifying monocular microscope with a lens as an observation device 1' and an eyepiece 2 ' on. The objective 1' is through a panel 3 ' limited in the opening. In a plane 4 ' of the intermediate image in front of the eyepiece 2 ' is a reticule 5 ' arranged whose version limits the field of view of the microscope and which by two crosshairs 6 ' marked two pixels in suitable horizontal distance. Between the lens 1' and the reticule 5 ' is a beam splitter cube 7 ' inserted, which is part of the ocular fundus 8th' reflected light laterally to an image plane 9 ' mirrored and usable for measurement purposes.

In the lateral plane oriented at right angles to the plane of the drawing 9 ' are two distant photodiodes 10 ' Mounted with a small measuring surface so centered that their places through the crosshairs 6 ' ( 2 ) of the reticule 5 ' correspond exactly to marked pixels. In 1 are the two photodiodes 10 ' behind each other. Both diodes are visible but appear congruent.

The lighting device 11 ' . 12 ' . 13 ' has as light source an incandescent or halogen lamp 11 ' with a small filament, a condenser 12 ' and an achromatic projection lens 13 ' on. Built into the lighting device are still a filter panel 14 ' and one of the projection lens 13 ' superior aperture diaphragm 15 ' ,

The illumination device is preferably arranged such that its optical axis is the optical axis of the microscope in its intermediate image plane 16 ' intersects at an angle α '. Expediently, the illumination takes place from above via a surface mirror fixedly arranged below the microscope axis 17 ' , so that the light with respect to the optical axis of the microscope from below at the angle α 'is incident. The inclined by the angle α 'direction of incidence of the light and a convenient dimensioning of the aperture 3 ' and 15 ' serve to keep disturbing reflections, caused by reflections on the surfaces of the refractive media, from the microscope beam path and in particular from the measuring beam path. The optics of the illumination device is designed so that the projection lens 13 ' the special filter panel 14 ' in the intermediate image plane 16 ' maps. Through one on the filter panel 14 ' vapor-deposited, opaque coating or by the formation of the filter aperture 14 ' can the illuminated field 18 ' ( 2 ) are limited in size. In the intermediate image plane 16 ' projected it should have a rectangular horizontal extent. Within the illuminated field, a filter pad is attached, which in the manner of an edge filter (for example, a long-pass filter) red light of the wavelength of about 600 nanometers and longer lets through (analog Wrattenfilter No. 25). However, this filter coating does not cover the entire illuminated field 18 ' but leaves around with the crosshairs 6 ' the reticule 5 ' designated pixels each have a small circular zone 19 ' open to the passage of "white" light. Its purpose is not to over-dazzle the patient, but nevertheless to allow the examiner to orient himself.

In the extension of the optical axis of the microscope on the intermediate image plane 16 ' In addition, there is an aspherical positive conversion lens 20 ' arranged in the manner of the "ophthalmoscopy lenses for indirect ophthalmoscopy" such that their rear (microscope-side) focal point primarily in or near the intermediate image plane 16 ' lies, but by means of a degree leadership 21 ' in the axial direction can also be moved by a few millimeters in both directions.

In the intermediate image plane 16 ' is also a perpendicular to the microscope axis two-dimensionally movable fixation mark 22 ' appropriate for a patient's eye 23 ' forms a fixing point.

The device described is characterized by a symbolically represented on a device table instrument base 24 ' worn and aligned with this by the examiner in front of the patient's eye three-dimensionally in the direction of the X, Y and Z spatial axes.

The signals of the two measuring diodes 10 ' be in a separate evaluation device 25 ' processed mathematically and the result displayed digitally.

In the following, the functions or the interaction of the previously described elements of the EP-A-0 608 516 known ophthalmic device will be described.

Prior to the examination, the pupil is dilated. The examiner regulates the eyepiece 2 ' of the microscope for his own eye 26 ' without accommodation on the built-in reticle 5 ' , As usual with such examination devices, the sitting patient supports his head with chin and forehead on a headgear. The examiner makes the device by means of the setting elements of the instrument base 24 ' aligned so that the conversion lens 20 ' frontally a few millimeters away from the eye 23 ' the patient comes to stand. At reasonably well centered alignment is the fundus 8th' now already visible. Depending on whether the patient has a refractive anomaly, the anterior lens is 20 ' move something in the direction of the optical axis. When Miopie shows the direction of displacement of the patient eye away, in case of hyperopia to this. The setting is correct if the examiner sees the retina sharply or if it is in focus. At the same time, it is ensured that the patient is in the intermediate image plane 16 ' the fixation point of the adjustably arranged fixation mark 22 ' can perceive sharply and be able to follow it if it is moved to another place by the examiner. In this way, it is easily possible to device and patient eye 23 ' align so that the retina sites selected by the examiner are preferably matched with the measurement points indicated by the tick marks. By means of the photodiodes 10 ' Now the light reflected from the selected retinal sites can be measured with the evaluation unit 25 ' evaluated and the measured value (s) are displayed. The evaluation device 25 ' forms, among other things, the quotient of that of the two photodiodes 10 ' determined brightness values by always dividing the higher value as a dividend and the lower (if it is not equal to zero) as divisor and displays it on a display. This quotient is a measure of the contrast transmission capability of the optical media of the patient's eye.

A very important prerequisite for exactly reproducible measurement results to obtain is meanwhile with the described elements and the specified working method not yet fulfilled. On this The circumstance will be discussed in more detail below.

For ease of illustration, the following discussion refers to an em-metropic patient's eye 23 ' , When adjusting to the latter prevails between the eye 23 ' and the conversion lens 20 ' parallel beam path. However, this has the consequence that slight shifts of the device in all three spatial axes cause neither a shift nor a sharpness decrease of the image in the eyepiece. Device shifting is limited only by the use of vignetting. Depending on the depth setting, a transverse movement of the device is relative to the eye 23 ' first a decrease of the brightness in the right or left part of the picture. In between there is an exactly defined depth position, where the whole picture is evenly attenuated in the brightness during a transverse movement. Meanwhile, both the observation beam path as claimed by the beam path beam cones are much narrower than the z. B. extended eye pupil free given space. However, different measurement results can also arise if, in the following measurements, different points of different transparency (turbidity) are irradiated in the eye media. Therefore, reproducible measurement results can only be obtained if it is possible to make the setting of the device also locally in the space of the eye media, ie with respect to the visual axis and the center of curvature of the cornea front surface exactly reproducible.

As an aid, on the one hand, the aperture diaphragm 15 ' the illumination device or its mirror image 27 ' On the other hand, the front surface of the cornea of the patient's eye is used as a spherical mirror. If one thinks of the patient's eye for the time being, then it is through the auxiliary lens 20 ' slightly outside its front focal point a brightly illuminated reduced image of the aperture diaphragm 15 ' generated. In the eye, this aperture image can be considered as a secondary source of light for the illumination of the retina. In the meantime, there is a sharp picture of the illuminated field with a red filter coating 18 ' the filter panel 14 ' with his field limitation. Now the device is in front of the patient's eye 23 ' aligned, that the above small picture of the aperture stop 15 ' Approximately halfway between the apex and the center of curvature of the Comeavorderfläche comes to lie, a part of the light is reflected by their acting as a spherical mirror surface and that as a parallel beam to the auxiliary lens 20 ' towards, ie that in the rear focal plane or in the intermediate image plane 16 ' turn a picture 15 '' ( 2 ) the aperture stop 15 ' arises.

With appropriate centering of the device is this picture 15 '' Visible in the microscope as a very bright sharply delimited circle image and repeatedly adjustable at the same point in the field of view during repeated measurements. However, this is the aperture image 15 '' relatively bright and could disturb the beam path. To avoid this, the device is centered on the one hand so that the aperture image 15 '' against the edge of the field of vision 29 ' to come to rest. Conveniently, it lies (as 2 shows) at the bottom when the microscope contains no image erecting system and at the top, if any. On the other hand, the intensity of the aperture image 15 '' through a near the intermediate image plane 16 ' arranged above the optical axis light-attenuating filter 30 ' greatly reduced. This circular filter 30 ' partially protrudes into the field of view of the microscope (about 1/3 of the diameter of the latter) and is in the eyepiece 2 ' slightly blurred perceived. Into this two-arc dark zone 30 '' becomes the aperture image 15 '' always set again with each new measurement ( 2 ). This setting method is very sensitive to the spatial-spatial repeatability of the setting and allows for very reproducible measurements at the same retinal sites.

Is in the case of other applications, only a reproducible adjustability of the device with respect to the center of curvature of the corneavor the surface of the patient's eye 23 ' required, may be the fixation mark 22 ' also omitted.

The device of EP-A 0 608 516 according to 1 and 2 Can be built as a stand-alone unit, as well as attachable or attachable accessory to a present in virtually every ophthalmology practice slit lamp device. In combination with a very common slit lamp model, it is possible to equip the slit lighting device with the described red filter, which eliminates an integrated lighting device. In this case, the deflection mirror is also 17 ' already exists.

Instead of the data acquisition device shown 10 ' . 25 ' a CCD camera and the like could also come with an automatic evaluation device which selectively performs, evaluates and displays the measurement at the two most important pixels. Another possibility is a photographic recording of the respectively examined retinal zone together with a marking of the measuring points.

The apparatus described above EP-A 0 608 516 Thus, in comparison to the previously known ophthalmic devices, such as those already cited in the above CH 662 261 has made significant progress, especially in terms of the reproducibility of the settings of the device in successive measurements or images of the ocular fundus.

A disadvantage of the device according to EP-A 0 608 516 However, among other things is that the effort of adjusting the device is relatively high and requires a high level of skill of the operator, so for example, the ophthalmologist or the optician. This means that the setting of the device takes a certain amount of time, which at the expense of the effectiveness of the work and on the other hand burden the patient unnecessarily long. One of the main drawbacks is that in the case of slight mispositioning, there is no corresponding feedback in which direction to correct. Apart from the clear input "wrong", there is no correction parameter. In particular, at this point, the present invention should begin.

There the serving person due to their own subjective perception Decide when the right setting of the device is found, is alone thereby the achievable measurement accuracy limited in some ways. This is even more true when facing each other following or different measurements of two different persons naturally, always have a slightly different subjective sense of vision, so that two settings, the two different people respectively as optimal, usually not exactly identical which leads to slightly different measurement results on and the same patient's eye can lead.

outgoing from this prior art, it is therefore the object of the invention, the reproducibility of the settings of an ophthalmological Device continues to improve, finding the optimal To objectify attitudes, that is to speak of the subjective To decouple perception of the serving person, while simultaneously the adjustment of the device significantly accelerated and for to simplify the operator. In particular, while a Manual adjustment by the operator as completely as possible be avoided.

Of the this object-solving object of the invention is characterized by characterized the features of independent claim 1.

The dependent claims relate to particular advantageous embodiments of the invention.

The The invention thus relates to an ophthalmological apparatus for optical and photometric examinations on an eye of a patient, comprising an observation device for monitoring one examining eye part, especially an eye fundus, in a predeterminable recording position of the eye, as well as a Measuring device with a measuring sensor for determining a position and / or an orientation of the eye with respect to the observer. According to the invention, an intensity and / or with the measuring sensor a direction of a on a surface, in particular to the cornea of the eye reflected measuring signal is measurable, so that with the help of the measuring sensor, the position and / or orientation of the Eye with respect to the observation device automatically determinable is.

Essential for the invention is thus that a measuring sensor for measurement an intensity and / or direction of one at a Surface, especially reflected on the cornea of the eye Measuring signal is provided, so that with the aid of the measuring sensor Measuring signal can be measured and from this measurement result Position and orientation of the eye with respect to the observer previously determined automatically for an examination of the eye can be.

In other words, the device serves to optically determine the position and orientation of a patient's eye to be examined. It will be an optical or photometric examination performed with an ophthalmic optic. Positions of optically imageable elements of the eye are determined, namely by means of a) light and / or sound waves, b) at least one light or sound-registering sensor and c) sensor signals evaluating devices. The sensor is arranged in front of, inside or behind the ophthalmic optics. Based on the determined measured values, data for the position and orientation of the patient's eye are calculated. As optically imageable elements are selected those which are visible outside the pupil on the eye. Simultaneously with the determination of an eye distance, ie the distance of the eye from the optics, the patient is acted upon by means of an optical stimulus in the form of a target target, in particular a luminous brand, in order to accomodate the patient, ie adjustment of the optical focus on the retina , and thus to initiate the setting of a target distance. A total optical distance of the retina is determined from the eye distance and the optical target distance.

In contrast to the direct imaging of the retina or a pattern projected onto the retina, as is the case with refractometers (see "An automatic objective optometer", Polse KA and Kerr KE, Arch. Ophthal. 93 (3), 225-231 (1975) ; "Automatic infra-red refractors: A comparative study", Wesemann W. and Rassow B., Am. J. Optom. Physiol. Opt. 64 (8), 627-638 (1987) ), the absolute position and orientation of the eye should be determined here. At the same time, the representation of a luminous target and a defined position, the optical distance of the retina are determined indirectly by the eye distance, ie the distance of the eye from the optics, and the total optical distance from the eye distance and the optical target distance is determined. Instead of a focus on the retina, the eye distance is measured and the focus of the eye specified.

It So is with the inventive device the optical distance of the retina indirectly determined by means of the target. The optical distance is in contrast to the corresponding geometric distance the distance of an image when viewing an imaged one Object (eg target target) appears. By optical elements or optically active zones affect the optical distance. she can also be infinite, zero or negative.

The Target target or target is a glowing object or a target projected luminous reference, which gives the patient on a given optical Distance appears.

The Meaning of the terms "optical distance" or "geometric distance" Distance ", as well as the meaning of the" target target ", also referred to as "fixation mark" in the context of this application, will be discussed below in connection with the description of the figures further defined and explained.

With The inventive device is that of the cornea backscattered signal used to connect to a detector either automatically track the recording system or else to take a picture if the patient's eye is correctly positioned is. As detectors, various known devices can be used.

in the Unlike with other devices Procedures, such as those used in refractometers, will be the Lens of the eye itself not taken into account. Rather, it will the patient is forced by a highlighter, to accommodate his eye lens to a certain distance (in usually to "infinite").

There the reflex is used on the cornea, more light is available than in procedures where retinal focus is detected directly; because On the one hand, the light does not have to go in and out through the narrow pupil on the other hand, it does not have to be high in light loss be reflected on the dark retina.

• – Durch die sekundäre Fokussierung auf eine Struktur vor der Retina muss kein von der Retina reflektiertes Licht aufgezeichnet werden. Dadurch wird das Auge weniger durch die Beleuchtung irritiert.
• – Es muss keine Strukturerkennung durchgeführt werden, womit die Methode sehr schnell sein kann. Eine Quadrantenmessung der Lichtverteilung kann in Mikrosekunden erfolgen. Zweidimensionale Streumuster können in wenigen Millisekunden erkannt werden. Damit können Autofokus und Ausrichtung ohne Stabilisierung geführt werden, d. h. weder der Patient noch die Vorrichtung müssen fixiert werden.
• – Die Erkennung braucht wenig Rechenaufwand. Die Leistung der CPU steht zur Bildverarbeitung zur Verfügung und nicht zum Führen der Optik. Dadurch sind leistungsfähigere Bildverarbeitungsalgorithmen realisierbar.
• – Es sind auch Systeme mit einem „low power mode” implementierbar, die nur dann rechnen müssen, wenn ein Bild vorliegt.
• – Es lässt sich nicht nur die Distanz des Augenhintergrundes (Retina) bestimmen, sondern auch dessen Position. Dadurch können Systeme oder die Patienten geführt werden. Die ”Fangbereiche” dieser Methoden variieren erheblich, d. h. die Systeme sind in der Lage das Auge zu lokalisieren, solange es in einem gewissen Bereich, dem Aufnahmebereich der Optik ist.
• – Anstatt einer intergrierten Optik, wie sie in Refraktometern bestehen, welche einen sehr grossen Zoom- und Fokalbereich abdecken müssen, werden zur Realisierung der Erfindung drei einfache Optikkomponenten verwendet, welche alle nur sehr wenig oder gar nicht flexibel sein müssen. Damit lassen sich die beweglichen Teile eliminieren oder stark reduzieren. a) Zielmarke wird oder kann auf fixer optischer Distanz eingeblendet werden. b) Fokus des Aunahmesystems kann fix ausgelegt werden oder auf Retinadistanz + Zielmarkendistanz – Distanz Optik zu Zielmarke. c) Distanzmessung braucht – je nach Auslegung – keinen Fokus.
• – Targetbeleuchtung, Fokusierung und Aufnahme können gleichzeitig aktiv sein und müssen nicht squentiell ausgeführt werden, was einen schnelleren Aufbau ermöglicht und Artefakte verhindert.

Advantages of the invention are listed below:

• - Secondary focusing on a structure in front of the retina eliminates the need to record light reflected from the retina. As a result, the eye is less irritated by the lighting.
• - No structure recognition has to be done, which makes the method very fast. A quadrant measurement of the light distribution can be done in microseconds. Two-dimensional scattering patterns can be detected in a few milliseconds. This autofocus and alignment can be performed without stabilization, ie neither the patient nor the device must be fixed.
• - The detection requires little computational effort. The performance of the CPU is available for image processing and not for guiding the optics. As a result, more powerful image processing algorithms can be realized.
• - Systems with a "low power mode" can also be implemented, which only have to calculate if an image is available.
• - Not only can the distance of the fundus (retina) be determined, but also its position. This allows systems or patients to be guided. The "capture ranges" of these methods vary considerably, ie, the systems are able to locate the eye as long as it is within a certain range, the pick-up area of the optic.
• - Instead of an integrated optics, as they exist in refractometers, which must cover a very large zoom and focal range, three simple optical components are used to implement the invention, all of which must be very little or not at all flexible. This eliminates or greatly reduces the moving parts. a) Target is or can be displayed at a fixed optical distance. b) focus of the antenna system can be fixed or at retinal distance + target distance - distance optics to target. c) Distance measurement needs - depending on the design - no focus.
• - Target lighting, focusing and recording can be active at the same time and do not need to be performed squared, allowing faster setup and preventing artifacts.

In an ophthalmological device according to the present invention, the observation device preferably comprises a lighting device for illuminating the eye part to be examined. The observation device as such can, moreover, several, preferably all features of the beginning on the basis of 1 and 2 in detail described ophthalomoligiecshen device according to EP 0 608 516 exhibit.

That is, in a very specific embodiment, an ophthalmological apparatus of the present invention is an embodiment of the apparatus according to EP 0 608 516 in which additionally a measuring device with a measuring sensor is provided, so that with the measuring sensor an intensity and / or a direction of a surface, in particular on the cornea of the eye reflected measurement signal is measurable, and with the aid of the measuring sensor, the position and / or the orientation of the eye with respect to the observation device is automatically determinable.

In this case, for example, an electronic evaluation unit may be provided which is connected to the measuring device and an adjusting means, for example with an instrument base 24 ' according to 1 is signal-connected for automatic adjustment of the observation device, so that the observation device with respect to the position and / or the orientation of the eye is automatically adjustable in position and orientation using the measured signal reflected at the cornea of the eye.

to Generation of the measurement signal is preferably at least one signal generator provided, wherein the signal transmitter, an optical signal transmitter and / or a is acoustic signal generator and / or wherein the lighting device for illuminating the eye to be examined at the same time as Signalers can be used. The acoustic signal is In this case, preferably an ultrasonic sensor, with which in particular spatially narrow ultrasound beams can generate, so that the position and / or orientation measurement by reflection on a surface of the eye with high spatial and temporal resolution can be performed.

Around the eye as well as possible during the examination to align with the direction of observation, the unavoidable eye movements spatially narrow and at the same time keeping an eye on one Distance, but not necessarily to infinity, or on to focus a given image plane, can be specified in a predefinable Viewing direction of the eye in an intermediate plane a fixation mark is placed to fix the line of sight of the eye, and / or wherein the fixing mark by means of a projecting device in the Intermediate level is projectable.

to Recording or recording of the eye to be examined can in a conventional manner a chemical and / or electronic Recording means, in particular a photographic camera, and / or a Video camera, and / or a digital camera and / or a CCD camera for photographic and / or electronic recording of the examined Be provided on the eye.

One particular advantage of the inventive ophthalmological Device is that the determination of the position and / or Orientation of the eye with respect to the observer can be done very quickly, especially in terms of speed, which inevitably causes the eye during the examination always moving. Therefore, it is possible that the measuring device the present invention permanently the position and / or orientation the eye measures, and once the eye is in the desired position and / or orientation with respect to the observer, automatically a recording z. B. by means of the CCD camera or by means of a other recording device initiated.

In such an embodiment, therefore, the eye only needs to be coarsely aligned with the observation device, possibly supported by a fixation mark already mentioned above. Respectively. the eye only needs to be brought close to the capture area; then the patient sees the fixation mark and the aiming device triggers the admission as soon as the patient has reached the optimal position or one of the optimal positions. Ie. Thus, an electronic evaluation unit may be provided in such a way and signal-connected with the measuring device that a recording of the eye part to be examined by means of the electroni recording means is automatically carried out when the eye is in the recording position.

In In practice, the eye to be examined, for example, the Iris or a blood vessel on the eyeball, with a camera imaged, wherein the camera is particularly preferred with a Autofocus focuses on the eye part to be examined, and a measured value for the focusing distance for the calculation the position and / or orientation of the eye is used, so that successive measurements can be reproduced even better be compared and compared with each other.

there it is only essential for the invention, that an optical or acoustic signal, sent by a Signal transmitter, so reflected on a surface of the eye is that it can be detected by at least one measurement sensor and from the measurement of the measuring sensor, the position and / or orientation of the eye with respect to the observer can.

in the In the most general case, neither the signal generator nor the Measuring sensor to be placed in an excellent position still have the signal transmitter and the measuring sensor in one geometrically excellent orientation or position to each other be arranged. Both can be manual or automatic, for example with the aid of a computer-controlled positioning device, be arranged movably.

Around the position and / or orientation of the eye with respect to the Observation device from the measured data acquired by the measuring sensor In the most general case, it only needs to be able to determine at the time of measurement the position and / or orientation of the Signal transmitter and / or the measuring sensor and / or the observation device to be known, or in a suitable manner known per se to those skilled in the art Way to be determined by the position and / or orientation of the eye with respect to the observer to be able to.

The can happen, for example, that from the position and / or Orientation data of the previously mentioned components of the ophthamological device at the time of measurement, as well from the measured data measured by the measuring sensor, the position and / or Orientation of the eye in relation to the observation of a data processing system is calculated. The help with a look-up table is also conceivable in the example position and / or orientation records and / or possible measurement results of the measuring sensor stored which are then used to determine the position of the eye in relation to the Observation direction can be used. The expert understands how he uses the possibilities exemplified above for determining the position of the eye with respect to the observer Use advantageous and possibly in a conventional manner yet can improve.

at one of the most important and preferred for practice The use of the present invention will become particular advantageously a property known per se from optics Spherical mirror exploited or applied.

there is by means of the lighting device and an upstream Opt a beam of light directed at the cornea of the eye, with the outer surface the cornea is used as a spherical mirror. The reflected from the cornea Light will come after a second pass through the upstream optics focused on a reflex point, the position of the Reflexpunkts for electronic data processing by means of the measuring sensor is measured and the relative position of the eye with respect to the observer, that the reflex point occupies a predetermined position, the one reproducible feasible examination of the patient's eye equivalent. This particular technique will be below in the frame the figure description discussed even more intense and based on Examples are clarified.

In In a specific embodiment, a layer and / or be an orientation of the measuring sensor and / or the signal generator flexible, d. H. the measuring sensor and / or the signal generator can be moved, z. B. slidably or rotatably and the measuring sensor and / or the signal generator can with a scheme such is designed to be in operation on changes in position of the reflex point with seek and capture movements.

Especially For example, the illumination device and / or the signal generator can be a moving measurement signal deliver, with which the reflex point to the predetermined position can be steered.

In particular, the device according to the invention thus enables a method for optically determining the position and orientation of a patient's eye to be examined, wherein an optical or photometric examination is carried out with an opthalmological optics, positions of optically imageable elements of the eye are determined by means of a) light and / or or sound waves, b) at least one light or sound-recording sensor, which is arranged in front of, inside or behind the ophthalmic optics, and c) Sensorig nal evaluating devices, and where, based on the measured values thus obtained, data for the position and orientation of the patient's eye are calculated. As optically imageable elements, those are selected which are visible on the outside of the pupil, thereby simultaneously with the determination of an eye distance, ie the distance of the eye from the optics, to the patient by means of an optical stimulus in the form of a target, in particular a illuminating mark, to cause the patient to accomodate, ie adjustment of the optical focus on the retina, and thus to set a target distance, wherein a total optical distance of the retina from the eye distance and the optical target distance is determined.

In A preferred application example is light as a light beam directed at the eye at a given angle, the light beam comes with a light source or ambient light as well as a collimator generated and reflected by the eye stray light is through the sensor recorded for subsequent evaluation.

there It is possible for a sharply delimited spot of light to appear the eye is projected that the location of the reflected light scattered is measured by means of the sensor, so that due to these measurements the distance of the eye from a reference point can be determined and that for a more precise and faster position determination instead of a light spot uses a plurality of such light spots can be.

at a special application example are the optically imageable Elements of the eye, in particular the iris or blood vessels on the eyeball, these elements being imaged with a camera be, and the camera with an autofocus, which is a conventional Autofocus, focusing on the elements, and a Measured value for the focusing distance for calculating the Position of the patient's eye is used.

Especially can ultrasonic waves by means of at least one transducer element be generated and received.

In Another application example is by means of a lighting device and an upstream optics directed a cone of light on the cornea, leaving the outer surface of the cornea as Ball mirror is used, with reflected light from the cornea after a second passage through the upstream optics a reflex point is bundled, and the position of the Reflexpunkts for electronic data processing by means of a sensor is measured, and the relative position of the patient's eye in terms of opthalmological optics is adjusted so that the reflex point occupies a predetermined position, the one reproducible feasible examination of the patient's eye equivalent.

Especially can change the position and orientation of the sensor with which the reflex point is measured, be flexible and the sensor with a scheme be formed so that it is responsive to changes in position of Reflective point reacts with search and capture movements, and / or the lighting device can provide a movable lighting, with which the reflex point can be steered to the specified position is.

The Invention will be described below with reference to the schematic drawing explained in more detail. Show it:

1 a known ophthalmological device according to EP 0 608 516 ;

2 the field of view in the eyepiece of the device 1 ;

3 a patient eye to be examined with devices according to the invention for determining its position and orientation;

4 Law of reflection on a spherical mirror;

5 an illustration for generating a concentrated reflex point on an optical axis, in the case that the patient's eye is in an ideal position;

6 the illustration of 5 shown as a longitudinal section, wherein the image plane extends along the optical axis;

7a - 7c Offset of the reflex point for three cases for which the patient's eye has moved out of the ideal position;

8a - 8d two-part fixation mark with illuminated cross;

9 Structure of the fixation mark according to 8a - 8d ;

10 Optical design of an ophthalmic device according to the invention;

11 simple construction with slit lamp.

The 1 and 2 show by way of explanation a known prior art. In order to distinguish the prior art from the present invention, the reference numerals in FIG 1 and 2 each provided with an apostrophe, while the reference numerals in the other figures, all of which relate to the invention, do not carry an apostrophe. Because the 1 and 2 already discussed in detail at the beginning, there is no need for further discussion here.

The strong schematic 3 gives two examples, as for a patient eye to be examined 2 using light rays 8th . 8a or 8th . 8b and sensors 61 . 61a respectively. 61 . 61b is used to determine position and orientation. On the eye 2 the following parts are indicated: the cornea (surface of the eye, where the measuring signal is reflected, in particular the cornea) 7 . 70 , the Lens 200 , the retina (retina, the eye part to be examined, in particular the fundus) 4 . 400 and the dermis 7 . 700 , An optical or photometric examination is made with an ophthalmic optic 1 carried out. An upstream optics 300 is between the eye 2 and ophthalmic optics 1 arranged. The upstream optics 300 may also be eliminated or part of the ophthalmic optics 1 be. Through the cornea 7 . 70 , the upstream optics 300 and the ophthalmic optics 1 extends an optical axis 1000 , With a light source 62 . 62a becomes the light beam 80 . 80a on the eyeball 7 . 700 (Outside of the dermis 700 ) projected where it is as a beam-shaped scattered light 8th . 8a in the sensor 61 . 61a is reflected. The light beam 80 . 80a could also be at the cornea 7 . 70 be reflected. Alternatively, the light beam 80 . 80b that comes from a light source 62 . 62b exit, in the cornea 7 . 70 broken, one being from the cornea 7 . 70 emerging light beam 8th . 8b by means of a sensor 61 . 61b is measured.

Positions of optically imageable elements of the eye 2 are determined by means of a) light and / or sound waves, b) at least one light or sound-registering sensor 61 . 61a . 61b located in front of, inside or behind the ophthalmic optics, and c) devices evaluating sensor signals. In the process, data for the position are obtained on the basis of the measured values obtained in this way 5 . 50 and orientation 5 . 51 of the patient's eye 2 calculated.

According to the invention are chosen as optically imageable elements such which are visible on the eye outside the pupil. Simultaneously with the determination of an eye distance, d. H. the distance of the eye from the optics, as explained later in more detail will be on the patient by means of an optical stimulus in the form of a target, in particular a luminous brand to help the patient to accomodate, d. H. Setting the optical focus on the retina, and thus setting a Cause target distance. A total optical distance of the retina is determined from the eye distance and the optical target distance.

In a particular embodiment of the present invention the ophthalmic device is an optical device, with the example of the optics of a fundus camera reproducible and automatically position against the eye. Both the distance between the eye and the optics of the fundus camera as well as the optical axes, so the orientation can be accurately positioned. This we in a special embodiment the invention achieved by a cone of light on the cornea is sent, with the light cone in the direction of the eye tapered so that the apex of the cone of light within the Eye comes to rest. Because the cornea is a substantially perfect one Spherical shell, becomes a part of the light, if the distance is right, reflected back as a parallel beam along the optical axis.

For clarification is in 4 The well-known reflection law is sketched on a spherical mirror: The spherical mirror K extends with radius r around the center point M. The focal point F of the spherical mirror is located on the optical axis 1000 at a distance r / 2 from the center M of the spherical mirror K. Now hits a convergent light beam 80 such on the specular surface of the spherical mirror K that a point of convergence of the convergent light beam 80 exactly to the focal point F within the spherical mirror K comes to rest, then the converging light beam 80 as a parallel beam 8th , parallel to the optical axis 1000 reflected by the spherical mirror K. Since, as already mentioned, the cornea is a practically perfect spherical shell, a ray of light incident on the cornea becomes 80 as reflected on a spherical mirror, what the present invention makes use of. It is understood that, for example when using an ultrasonic beam instead of a light beam analogous laws for the reflection on the surface of the spherical mirror K apply.

If a distance is too short or too long, so that the point of convergence of the incident light beam 80 does not come to rest on the focal point F is the reflected beam 80 no longer parallel, but either convergent or divergent. The direction of the optical axis finally determines the direction in which the reflected radiation is reflected. Thanks to this precise repositioning, the light reflected by the retina, which can also originate from another light source, can then be quantitatively evaluated during an eye examination.

The above will be explained later on the basis of 5 to 7c discussed in more detail.

According to the invention uses the backscattered signal with a suitable detector, for example with an optical or acoustic sensor, the expert in many variants are well known, either nachzuführen the recording system automatically or to take a picture at the very moment when that Eye is positioned correctly. Unlike other devices, as used in refractometers, for example the determination of the position and orientation of the eye neither the lens the vitreous of the eye is still used, but it is evaluated only the outside of the eye reflected signal, so that Damping losses, absorption, refraction and other effects, which can influence a measurement signal in the interior of the eye an apparatus of the present invention play no role. Thus, in particular, more light is available, because the light does not enter through the narrow pupil of the eye and must leak again before it is evaluated for positioning becomes.

Prefers can, as also discussed in more detail later, used a highlighter that forces the patient's eye to camera the eye lens to a certain distance. In many Cases, for the sake of simplicity, the eye is forced on to accomodate infinite distance.

In 5 schematically illustrates a situation for generating a concentrated reflex point on an optical axis in the event that the patient's eye is in an ideal position. The illustration of 6 is a longitudinal section according to 5 wherein the image plane extends along the optical axis.

The 5 and 6 give an illustration to the previously roughly described method, such as a concentrated reflex point according to EP-A-0 608 516 for the purpose of positioning the patient's eye 2 can be generated. By means of a lighting device, not shown 3 , or signal generator 62 . 62a . 62b , the light 600 emit, and the upstream optics 300 becomes a cone of light with rays 8th . 80 . 81 on the cornea 7 . 70 directed. The Rays 81 lie on the lateral surface of the light cone.

In 5 is the upstream optics 300 in the form of a flat cylinder 300 symbolizes, being from this cylinder 300 only the back half is shown. The outer surface of the cornea 7 . 70 is used as a spherical mirror. Is the cornea 7 . 70 in one location, namely the ideal location, in which an optimal picture of the retina 4 . 400 can be obtained, so that forms of the cornea 7 . 70 reflected light a bunch of parallel rays 8th . 83 , After a second pass through the upstream optics 300 the reflected light is at a reflex point 2000 bundled.

In 6 (Longitudinal section to 2 with an image plane that extends along the optical axis 1000 extends) are shown dashed rays that are within the light cone or the reflected light beam.

Starting from the in the EP-A-0 608 516 disclosed device extends the invention according to a particular embodiment, the known device. With the mentioned device is the exact position of the cornea 7 . 70 in front of an opthalmic optic 3 detectable by a single concentrated reflex point 2000 on the optical axis 1000 is generated (Alinierung). According to the extension of the known apparatus by the present invention, the scatter pattern or a part of the scatter pattern of the cornea becomes 7 . 70 detected when there is no alination, ie the cornea 7 . 70 not perfectly positioned. In the special case of alination, the scattering pattern converges to that in the EP-A-0 608 516 described single reflex point 2000 ,

In case of a deviation of the cornea 7 . 70 the ideal position produces an offset 2001 of the reflex point 2000 the ideal position, as in the 7a - 7c is shown. Dash-dotted lines are the ones on the reflex point 2000 directed cone, as indicated in the ideal position of the eye 2 in relation to the observation device 3 is to be expected.

In 7a is the eye 1 too far from the upstream optics 300 away (and thus too far away from the observer 3 ophthalmic optics 1 ). It narrows a reflected light beam 8th . 83 , and a new reflex point 2001 has a longitudinal offset to the upstream optics 300 towards.

In 7b with too close eye 2 expands a reflected light beam 8th . 83 , and a new reflex point 2001 has a longitudinal offset away from the upstream optics 300 on.

In 7c is the eye 2 moved transversely to the left. A reflected light beam 8th . 83 creates a new reflex point 2001 which is shifted transversally to the right.

• a) qualitativ festzustellen, in welche Richtung die Cornea 7, 70 von der Idealposition abweicht,
• b) in einem kleineren Bereich zu bestimmen, wie gross der Versatz ist.

In the case of an offset, the scatter pattern can be evaluated, namely

• a) determine qualitatively in which direction the cornea 7 . 70 deviates from the ideal position,
• b) to determine in a smaller area how big the offset is.

The position of the reflex point 2000 (respectively. 2001 ) is used for electronic data processing by means of the measuring sensor 61 (not shown in the 7a - 7b ) measured. The relative position of the patient's eye 2 with respect to the observation device 3 the opthalmological optics 1 or the relative position of the observation device 3 to the patient's eye 2 is adjusted so that the reflex point 2000 assumes a predetermined position that a reproducible feasible examination of the patient's eye 2 equivalent.

Supplies the lighting device 62 a rigid lighting, so must the measuring sensor 61 with which the reflex point 2000 is measured, be flexible, so that the position and orientation of the measuring sensor 61 can be changed. The sensor 61 must be designed with a scheme such that it changes the position of the reflex point 2000 reacts with search and capture movements. Alternatively, a fixed sensor 61 possible if the lighting device provides a movable lighting, with which the reflex point 2000 can be directed to the predetermined, the reproducible feasible examination corresponding position.

It Alternatively to the mere determination of the patient's position, the optical recording system tracked to the patient to follow. The scattering pattern depends on the position of the patient in all three spatial axes, from the orientation of the patient and also on the structure of the lighting.

• i) die Auswertung kann äusserst schnell erfolgen.
• ii) Die Lichtquelle kann monochromatisch, polarisiert oder moduliert ausgelegt werden, um sie unempfindlich gegen Umgebungslicht und Störeinflüsse zu machen.
• iii) Die Lichtquelle kann mit Infrarot oder Ferninfrarot betrieben werden, weil sie ja nicht ins Auge transmittiert werden muss. Damit löst die Quelle keine Pupillenreflexe im Patienten aus.
• iv) Das Detektionssystem (Sensoren) kann klein ausgebildet und peripher angebracht werden, um die Aufnahmeoptik nicht zu beeinträchtigen.

The backscattered light can be evaluated without complex image recognition, since the backscattered light always converges in exactly one point. This brings significant benefits:

• i) the evaluation can be extremely fast.
• ii) The light source can be monochromatic, polarized or modulated to make it insensitive to ambient light and noise.
• iii) The light source can be operated with infrared or far infrared, because it does not have to be transmitted to the eye. The source does not trigger pupil reflexes in the patient.
• iv) The detection system (sensors) can be made small and peripherally mounted so as not to affect the recording optics.

When determining position 50 and orientation 51 of the patient's eye to be examined 2 can light as a ray of light 80 . 80a or 80 . 80b (please refer 3 ) at a predetermined angle to the eye 2 be directed. The light beam 80 . 80a . 80b settles with a light source 60 . 60a respectively. 60 . 60b or ambient light and a collimator. That of the eye 2 reflected scattered light 8th . 8a respectively. 8th . 8b is through the sensor 61 . 61a respectively. 61 . 61b recorded for subsequent evaluation.

It a sharply defined spot of light can be projected onto the eye. The position of the reflected scattered light is determined by means of a sensor measured so that, based on these measurements, the distance of the eye can be determined from a reference point. To a more precise and faster positioning can be done instead of a light spot a plurality of such light spots are used.

The optically imageable elements of the eye, in particular the iris or blood vessels on the eyeball are at one particular embodiment of the invention with a camera displayed. In doing so, the camera will focus on autofocus the said elements are sharp. A reading for the focus distance is used to calculate the position of the patient's eye.

Instead of Light can also be used ultrasonic waves. Of the Ultrasound is generated by means of at least one transducer element and receive. The evaluation of scattered ultrasound is equivalent for the use of light, with the advantageous exception that when Ultrasound method also run times can be evaluated.

As already mentioned, a fixation mark is preferred, often Also referred to as a target, which stimulate the eye of the patient to do so intended to focus on a specific image plane. In many cases will this may be the infinite level, but not fundamentally is required.

In the 8a to 8d a preferred embodiment of a fixation mark 9 . 91 . 92 shown schematically, the advantageous of two elements 91 . 92 and designed to appear to the patient as "optimal" in terms of shape and symmetry when the patient's eye is exactly on the optical axis of the system.

In the in the 8a to 8d illustrated special embodiment of a fixing mark 9 . 91 . 92 , is the fixation mark 9 . 91 . 92 executed in two parts and includes a first part mark 91 ( 8a ), by a circular semi-transparent surface 911 and a completely transparent cross 912 is formed. Next includes the fixation mark 9 . 91 . 92 a second part mark 92 ( 8b ), from a likewise circular dark background 921 and a luminous cross 922 is formed. It is understood that the shape of the fixation mark 9 . 91 . 92 In principle, it is freely selectable, that is, not necessarily circular, and the transparent, semitransparent, dark background and crosses are interchangeable with other suitable geometric shapes. In addition, the need both partial brands 91 . 92 not necessarily the same size. The fixation also need not be arranged spatially one behind the other; they only have to appear visually different.

A possible structure and functioning of the fixation mark 9 . 91 . 92 is in the 8c and 8d sketched schematically. The fixation mark 9 . 91 . 92 forms a system of the luminous cross 922 and the semi-transparent surface 911 , The second part mark 92 with the luminous cross 922 becomes in relation to the eye of the patient behind the first partial mark 91 with the transparent cross 912 assembled. The crosses are aligned on the optical axis. In 8c is a view of the fixation mark 9 . 91 . 92 how it turns out when the fixation mark 9 . 91 . 92 not viewed from the optical axis. As in 8d shown are the crosses 912 . 922 on the other hand, they fit perfectly together when viewed from the optical axis.

In 9 is a possible optical structure of the fixation mark 9 . 91 . 92 according to 8a - 8d shown schematically.

The luminous cross 922 is fixed at the distance of the focal length f from the optical system. The semitransparent partial mark 91 is placed in front of it. The image plane of the fixation mark 9 . 91 . 92 is now determined by the focal length f of the optical system and the position of the illuminated cross 922 specified. If the position of the front main plane (as shown left in 9 ) of the system takes as origin O and the system has a total focal length of f and the mark 92 is at m, then applies to the image plane: 1 / b = 1 / f - 1 / m

In most cases you will, as in 9 shown, put m straight on f so that the image plane b comes to infinity.

Because the semi-transparent area 911 is not in the desired image plane, it should be visually less conspicuous or appealing designed as the light cross 922 so that the patient does not reach the semi-transparent area 911 akkomodiert.

For clarification and conceptual clarification is in 10 in a highly schematic representation of the optical structure of an inventive ophthalmic device outlined.

The "optical distance of the retina 4 . 400 "Is the image plane in which the retina 4 . 400 the image sensor 3000 So for example a CCD camera 3000 for receiving the retina 4 . 400 appears. From the representation of the right main plane of the ophthalmic optics, the physical distance of the retina is r, but the optical distance is O with: 1 / O = 1 / f - 1 / b.

In most cases, the image sensor 3000 lie in the focal plane of optics, so that O is equal to infinity, which means nothing else than that the retina 4 . 400 in the focal plane of the system of cornea 7 . 70 and lens 200 lies. The purpose is the optical distance O of the retina 4 . 400 To set is to be able to use a fixed focus in the recording optics, so that it does not have to be set again and again.

If one knows the eye position and the optical distance to the retina is given, then there are no further adjustments on the path of the receiving optics 1 . 3 to the image sensor 3000 more necessary.

In 11 Finally, a very simple functional construction of an ophthalmological device according to the present invention is shown. For the sake of clarity, the means for automatically determining the position and / or orientation of the eye in 11 not shown.

For observation of the retina 4 . 400 becomes the eye 2 illuminated by the patient with the slit lamp L. The slit lamp L is angled away from the optical axis. As a result, the slit lamp L does not disturb the receiving path and the reflections in the eye are attenuated.

The image of the illuminated retina 4 . 400 is from a chromatically corrected lens arrangement 31 collected and displayed. Because the retina 4 . 400 is not even, the so-called field curvature is partially compensated by an inversely distorted figure. The Kuvaturlinsen 32 form the curved image plane of Achromaten 31 to the level of the image sensor 3000 from. If one does not use an image sensor for observing the retina, but instead the human eye as an image sensor 3000 , then the Kuvaturkompensation is unnecessary and can be omitted.

It is understood that all inventive embodiments described in this application are to be understood as exemplary only and, as described or suggested in the context of the present application, either alone or in any suitable combinations in specific embodiments of inventive ophthamolgischer devices may be provided so that also all suitable combinations of the embodiments of devices described in this application by the present Er are recorded and covered.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - CH 662261 [0002, 0025]
• - EP 0608516 A [0003, 0006, 0007, 0016, 0023, 0025, 0026, 0089, 0092, 0092]
• - EP 0608516 [0042, 0043, 0067]

Cited non-patent literature

• - "An automatic objective optometer", Polse KA and Kerr KE, Arch. Ophthal. 93 (3), 225-231 (1975) [0034]
• - "Automatic infra-red refractors: A comparative study", Wesemann W. and Rassow B., Am. J. Optom. Physiol. Opt. 64 (8), 627-638 (1987) [0034]

Claims (8)

Ophthalmological device for optical and photometric examination of one eye ( 2 ) of a patient, comprising an observation device ( 3 ) for observation of an eye part to be examined ( 4 . 400 ), in particular an ocular fundus ( 4 . 400 ) in a predefinable recording position ( 5 ) of the eye ( 2 ), as well as a measuring device ( 6 ) with a measuring sensor ( 61 ) for the determination of a position ( 50 ) and / or orientation ( 51 ) of the eye ( 2 ) with regard to the observer ( 3 ), characterized in that with the measuring sensor ( 61 ) an intensity and / or a direction of a surface ( 7 . 70 . 700 ), especially on the cornea ( 7 . 70 ) of the eye ( 2 ) reflected measuring signal ( 8th . 8a . 8b ) is measurable, so that with the help of the measuring sensor ( 61 ) the position ( 50 ) and / or orientation ( 51 ) of the eye ( 2 ) with regard to the observer ( 3 ) is automatically determinable. Apparatus according to claim 1, wherein the observation device ( 3 ) a lighting device for illuminating the eye part to be examined ( 4 . 400 ). Device according to one of claims 1 or 2, wherein a signal generator ( 62 . 62a . 62b ) for generating the measurement signal ( 8th ) is provided. Device according to one of the preceding claims, wherein the signal generator ( 62 . 62a . 62b ) an optical signal transmitter ( 62 . 62a . 62b ) and / or an acoustic signal generator ( 62 . 62a . 62b ) and / or wherein the signal generator ( 62 . 62a . 62b ) the illumination device ( 3 ). Device according to one of the preceding claims, wherein in a predefinable viewing direction of the eye ( 2 ) in an intermediate plane a fixation mark ( 9 . 91 . 92 ) for fixing the line of sight of the eye ( 2 ), and / or wherein the fixation mark ( 9 . 91 . 92 ) can be projected into the intermediate plane by means of a projection device. Device according to one of the preceding claims, wherein an electronic evaluation unit is provided, which is connected to the measuring device ( 6 ) and an adjusting means for automatic adjustment of the observation device ( 3 ), so that using the reflected measurement signal ( 8th . 8a . 8b ) the observation device ( 3 ) in relation to the position ( 50 ) and / or orientation ( 51 ) of the eye ( 2 ) is automatically adjustable. Apparatus according to one of the preceding claims, wherein a chemical and / or electronic recording medium ( 3000 ), in particular a photographic camera, and / or a video camera, and / or a digital camera and / or a CCD camera for the photographic and / or electronic recording of the eye part to be examined ( 4 . 400 ) is provided. Device according to one of the preceding claims, wherein an electronic evaluation unit provided in such a way and with the measuring device ( 6 ) is connected to a recording of the eye part to be examined ( 4 . 400 ) by means of the electronic recording means ( 3000 ) is automatically carried out as soon as the eye ( 2 ) in the recording position ( 5 ).