DE102012019468A1 - Device for determining cornea curvature of eye, has image recording unit and control and evaluation unit which is connected to illumination source and image pickup unit, so that telecentric aperture of swivel is varied - Google Patents

Device for determining cornea curvature of eye, has image recording unit and control and evaluation unit which is connected to illumination source and image pickup unit, so that telecentric aperture of swivel is varied

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Publication number
DE102012019468A1
DE102012019468A1 DE201210019468 DE102012019468A DE102012019468A1 DE 102012019468 A1 DE102012019468 A1 DE 102012019468A1 DE 201210019468 DE201210019468 DE 201210019468 DE 102012019468 A DE102012019468 A DE 102012019468A DE 102012019468 A1 DE102012019468 A1 DE 102012019468A1
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mm
aperture
eye
characterized
preferably
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German (de)
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Matthias Reich
Rico Fuchs
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Carl Zeiss Meditec AG
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Carl Zeiss Meditec AG
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Priority to DE201210019468 priority Critical patent/DE102012019468A1/en
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    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B3/00Apparatus for testing the eyes; Instruments for examining the eyes
    • A61B3/10Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions
    • A61B3/107Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions for determining the shape or measuring the curvature of the cornea
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B3/00Apparatus for testing the eyes; Instruments for examining the eyes
    • A61B3/10Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions
    • A61B3/14Arrangements specially adapted for eye photography

Abstract

The device has light source which collimates structured lighting. An illumination source performs planar illumination of an eye (1). The illumination source is provided with a detection beam path that is provided with an aperture stop (2), a lens (3) and a telecentric aperture (4). An image recording unit and a control and evaluation unit is connected to the illumination source and the image pickup unit (5), so that the telecentric aperture of swivel is varied. An independent claim is included for method for determining cornea curvature of eye.

Description

  • The present invention relates to a solution for determining the curvature properties of the cornea of an eye by means of topographical or keratometric measurement, as well as to register the measurement.
  • The measurement of the cornea, d. H. whose curvature properties, is also referred to as keratometry and z. B. with the aid of a so-called ophthalmometer (keratometer). A special form of keratometry is topometry. Measured here are the radii of curvature central and peripheral. Based on these measurements, a contact lens fitting can be made. The central values of keratometry or topometry are used to describe the course of the surface of the cornea. In addition to the adaptation of contact lenses, keratometry is used primarily for the diagnosis of irregular deformations, in particular keratoconus, and for the calculation of an intraocular lens.
  • The surface measurement of the cornea of the human eye proves to be difficult, since the cornea is transparent and visible light is not backscattered to any significant extent.
  • The cornea (cornea) is the foremost part of the eye and has a convex, specific geometry. To capture this geometric shape of the anterior corneal surface in its entirety, one makes use of the topography. The front surface shape may vary, with two of the most important and well-known being the spherical (spherical) and the astigmatic (curved) cornea.
  • With a refractive power of more than 40 diopters, the cornea is a significant factor in the refraction of the light entering the eye. The refractive power of the cornea depends primarily on the high refractive index jump, the shape of the corneal surface and in particular its curvature. The determination of the shape of the corneal surface is particularly important in the following areas of application:
    • Cataract surgery, combined with astigmatism reduction,
    • • contact lens fitting,
    • • detection of keratoconus,
    • • corneal determination of astigmatism,
    • • refractive surgery and
    • • Adaptation of suitable glasses.
  • In surgical applications, the determination of the surface shape of the cornea of an eye is important both before and after surgery because the surface shape is suitable for detecting abnormal or abnormal forms of the cornea.
  • A method for measuring the corneal surface shape with the aid of so-called keratometers or keratographs has long been known in the prior art. The concentric rings of the Placido disk, which are shown on the cornea, are reflected by the tear film of the cornea and recorded and evaluated with a camera. Depending on the curvature of the cornea, the reflected ring pattern detected by the camera is distorted. In order to obtain a determination of the curvature from these reflection signals, the distortions of the rings must be compared with a known shape, which is usually chosen as a sphere with a radius of 7.8 mm. Such a solution is for example in the Scriptures US 4,685,140 A described.
  • The US 4,660,946 A describes a corneal shape measurement solution based on a disk-shaped Fresnel cylindrical lens. To project the ring structure onto the eye, each ring of the Fresnel cylindrical lens is individually illuminated annularly by means of ring cylindrical lenses. On the one hand, the number of rings that can be realized is limited by the disc-shaped structure, and on the other hand, with increasing number of rings, this type of illumination can only be realized with difficulty.
  • In the scriptures US 6,575,573 B2 and US Pat. No. 6,692,126 B1 solutions to ophthalmometers (also known as keratometers) are described, which are supplemented by slit illumination units. While the imaging of placidoring systems for measuring the surface curvature of the cornea of the eye is provided, the gap illumination unit generates sectional images of the eye, from which the thickness of the cornea of the eye can be determined. As a result of this combination, a corneal thickness profile can be determined.
  • Also in the not yet published font DE 10 2011 102 355.4 described system for determining the topography of the cornea of an eye provides the use of an element with Fresnel structure for the generation of rings. However, the element here is a fused axicon with ring-shaped structures of different radii, which is illuminated over its entire surface with ring-shaped, plane waves.
  • Instead of a "cone-shaped" plane wave, many of the collimated partial waves are generated per facet from the contoured axicon, so that ring-shaped point chains result in the detector image. Another important advantage of the faceted structures is that strongly aspherical surfaces can be measured, which for example, offers the possibility to measure very strong cylinder errors in the order of 15 dpt.
  • Further keratometric measuring arrangements are, for example, in the publications DE 197 26 291 A1 and DE196 36 472 A1 described. Both arrangements are based on the illumination of the cornea with parallel light beams, the structures such. B. generate dot or ring pattern. Curvature radii of the cornea can be determined on the basis of the known properties of illumination and detection optics. An advantage of these systems is the collimated illumination (from the infinite), which together with a telecentric detection makes the imaging on the detector independent of the distance of the object from the measuring device. Wavelengths in the infrared range are preferably used for illumination, so that the patient is not distracted from the fixation.
  • The determination of the shape of the surface of the cornea and in particular its curvature, however, only represents a significant factor for the o. G. Areas of application. Almost equally important is the assignment of the measured values to the orientation of the eye during the measurement. This assignment is also called registration and is particularly important for surgical procedures on the eye. Only by an exact registration of the ascertained surface shape of the cornea can it be ensured that the right places of the cornea are treated.
  • The writings US 6,702,806 B2 and US 7,815,631 B2 describe systems for aligning or registering diagnostic data of an eye at the time of a first measurement with the eye at the time of a second measurement or an OP. The orientation of the eye during a first measurement is detected using predetermined eye features. On the basis of these predetermined eye features, the orientation of the eye during a second measurement or during an operation is compared with the orientation of the eye during the first measurement. It is possible to calculate a change in the orientation accordingly and, if necessary, to correct for a surgical procedure on the eye. As an eye-sight to determine the orientation of the eye limbusnahe, extra-corneal structures, such as scleral blood vessels, are used. Wavelengths in the green area are preferably used, since the blood of the scleral vessels absorbs particularly well here.
  • The corneal curvature measurement systems described above operate with telecentric imaging, i. H. only the beams are left through the telecentric end, whose main beam is parallel to the optical axis. This is only possible with a correspondingly small opening of the telecentric screen.
  • The refractive effective area on the eye is the central optical zone. Observing standard pupil dimensions and vertex-pupil displacement, the central region of interest for the measurement has a diameter of about 8-9 mm. An illumination of this zone is also only possible centrally, ie near the optical axis, which complicates the decoupling of the observation radiation due to space problems accordingly.
  • The o. G. Systems for registration use structures that lie near the limb in the sclera area and thus outside the cornea. This means that the necessary image area is laterally as well as axially different from the central area of the cornea, because the sclera plane lies about 3 mm behind the corneal plane, the limb-near sclera area is approximately> 11 mm in diameter.
  • The system for registration, which uses external image sections, is thus in contrast to the telecentric optics, which is intended to image central areas with a small aperture. With the telecentric optics it is therefore not always possible to detect external image areas, which are necessary for later registration of the measurement data to the eye.
  • In the solutions of the prior art therefore often sequential images of the individual areas are made, with different lenses are used. It should be noted that eye movements can occur that lead to errors in the registration. Therefore, with sequential recording, the switching time should be as small as possible. A disadvantage in this context, however, is that the use of lens changers lead to more complex and expensive systems. In addition, lens changer with multiple lens systems are also large and heavy, so that fast switching is not possible.
  • It is an object of the present invention to develop a registered corneal curvature determination solution that overcomes the disadvantages of the prior art solutions while providing a low switching time for sequential acquisitions to accommodate erroneous eye movement measurements avoid.
  • This object is achieved with the inventive apparatus for the registered determination of the curvature of the cornea of an eye, consisting of a first illumination source for collimated, structured illumination and a second Illumination source for flat illumination of an eye, a detection beam path in which, starting from the eye, an aperture stop, an objective, a telecentric aperture and an image acquisition unit are arranged, and a control and evaluation unit which has connections to the two illumination sources and the image acquisition unit, in that the telecentricity aperture is pivotable or variably configured as a dichroic or its diaphragm opening.
  • According to the method of the invention, the eye is illuminated in area by a first illumination source with collimated, structured light or by a second illumination source and the light reflected by the eye is imaged onto an image acquisition unit via an aperture stop, an objective, a telecentric aperture and transmitted to a control and evaluation unit , Depending on the illumination source used, the telecentric screen is swiveled in or out of the beam path or its aperture is varied in order to determine either the curvature of the cornea of the eye or its registration. In contrast, a telecentric screen designed as a dichroic can remain in the beam path.
  • According to the invention the object is solved by the features of the independent claims. Preferred developments and refinements are the subject of the dependent claims.
  • The inventive solution is provided in particular for keratometric measuring arrangements, in addition to the determination of the curvature of the cornea of an eye to make a registration of the measured values can, without possible eye movements between recordings lead to incorrect registrations.
  • The invention will be described in more detail below with reference to exemplary embodiments. These show:
  • 1 : the detection beam path of the device according to the invention for determining the curvature of the cornea of an eye,
  • 2 : the detection beam path of the device according to the invention for determining registration data without telecentric aperture,
  • 3 : the detection beam path of the device according to the invention for determining registration data with telecentric aperture and
  • 4 : The detection beam path of the device according to the invention with a dichroic telecentric aperture for the simultaneous determination of the curvature of the cornea of an eye and its registration data.
  • According to the invention, the solution is used for the diagnosis of curvature properties of the cornea of an eye and the determination of registration data for later alignment.
  • While the diagnostic data of the central corneal area are recorded telecentrically in collimated structured illumination, the sequential acquisition of the registration data of the external sclera area is non-telecentric.
  • The device according to the invention for the registered determination of the curvature of the cornea of an eye consists of a first illumination source for collimated, structured illumination and a second illumination source for planar illumination of an eye, a detection beam path in which, starting from the eye, an aperture stop, a lens, a telecentric aperture and a Image recording unit are arranged, and a control and evaluation unit having connections to the two illumination sources and the image pickup unit. It is essential to the invention that the Telezentrieblende is designed to be pivotable or variable as a dichroic or the aperture.
  • While the first illumination source for collimated, structured illumination is based on long-wave, preferably infrared, light, the second illumination source for flat illumination of the eye uses short-wave, preferably green or blue light.
  • The collimated, structured illumination is done as in the prior art systems and may include dots, rings or other patterned patterns. Wherein the structuring can be done by wavelength differences, shape differences, screen density differences or intensity differences.
  • The objective arranged in the detection beam path between the aperture stop and the telecentric aperture is preferably chromatically corrected in such a way that the telecentric imaging in the infrared region and the non-telecentric imaging is optimized for the green or blue region. The use of the illumination wavelength for the non-telecentric imaging is adapted to the respectively used structure or the used feature of the eye.
  • The use of large wavelengths for the curvature measurement and of small wavelengths for the registration measurement of Advantage, wherein the dispersion correction must be such that the larger wavelengths focus shorter, so that the above properties of the planes to be reproduced are compensated.
  • According to the invention, the control and evaluation unit has additional connections to adjusting elements which are present for the realization of the pivot movement or the diameter variation. In addition, the image acquisition unit is designed so that both central, telecentric images of the cornea and non-telecentric images of the outer sclera region can be realized at different wavelengths of the illumination light.
  • For telecentric imaging, the opening of the telecentric screen is adjusted so that only narrow cones of the parallel reflection beams of the structured collimated illumination of the central corneal zone are left through the telecentric end. The aperture is small.
  • In contrast, the aperture of the telecentric aperture for non-telecentric imaging is chosen to be large so that the marginal rays of the outer region with the extra-corneal structures are still imaged.
  • While in the mode of determining the grain curvature, the telecentric aperture represents the aperture bounding the beam path, the beam path is limited in the mode of determining the registration of the aperture stop.
  • The aperture of the aperture stop located in the detection beam path is unchanged during both measurement modes. According to the invention, it has an aperture of 10 mm to 25 mm, preferably up to 20 mm and particularly preferably up to 15 mm. The aperture stop does not necessarily have to be present as a separate optical element but can also be present in the form of beam limitations in the objective.
  • In contrast, the aperture of the telecentric bezel is adapted to the respective measurement mode. For this telecentric pivot is pivotable or the aperture is made variable.
  • In a first embodiment of the device according to the invention, the pivotable telecentric screen has an aperture of <13 mm, preferably of <9 mm and particularly preferably of <8 mm. For example, depending on the optics used, the aperture can be as small as 5-6 mm in diameter. This pivoting telecentric bezel is pivoted to measure the corneal curvature in the beam path and then removed from this.
  • This shows the 1 the detection beam path of the device according to the invention for determining the curvature of the cornea of an eye. In the detection beam path are starting from the eye 1 , an aperture stop 2 , a lens 3 , a telecentric screen 4 and an image pickup unit 5 arranged, which is connected to a control and evaluation unit, not shown. The telecentric screen is located to measure the corneal curvature in the detection beam path.
  • According to the 1 has the telecentric aperture arranged in the detection beam path 4 for the telecentric determination of the curvature of the cornea on a correspondingly small aperture, whereby a large depth of field can be achieved. The small aperture of the telecentric screen 4 can only be passed by the parallel main rays.
  • The 2 shows in contrast to the detection beam path of the device according to the invention for the determination of registration data without telecentric screen. In the detection beam path are starting from the eye 1 , an aperture stop 2 , a lens 3 and an image pickup unit 5 arranged, which is connected to a control and evaluation unit, not shown. The Telzentrieblende is swung to determine registration data from the detection beam path.
  • According to the 2 No telecentric aperture is arranged in the detection beam path for the determination of registration data, as a result of which aberrant structures of the outer sclera area are imaged, since non-parallel principal rays from the peripheral edge region are also imaged on the image acquisition unit 5 reach.
  • In a second embodiment of the device according to the invention, the telecentric aperture is designed so that its smallest aperture opening <13 mm, preferably <9 mm and particularly preferably <8 mm or its largest aperture> 16 mm, preferably> 13 mm and particularly preferably> 11 mm is. This telecentric aperture with variable aperture is adapted to the respective measurement mode. While the smallest aperture is selected to measure the curvature of the cornea, the registration data is measured using the largest aperture.
  • This shows the 3 the detection beam path of the device according to the invention for the determination of registration data with telecentric screen. In the detection beam path are starting from the eye 1 , an aperture stop 2 , a lens 3 , a telecentric screen 4 and an image pickup unit 5 arranged, which is connected to a control and evaluation unit, not shown. The telecentric aperture 4 has a variable aperture and uses the largest aperture to determine the registration data.
  • According to the 3 is a telecentric aperture in the detection beam path for the determination of registration data 4 arranged with a correspondingly large aperture, are imaged by the extra-corneal structures of the outer sclera, as well as non-parallel main rays from the peripheral edge region on the image pickup unit 5 reach.
  • The aperture of the telecentric screen 4 is adapted to the respective measuring mode. To measure the curvature of the cornea, the telecentric aperture points 4 accordingly, the smallest aperture on.
  • As a telecentric aperture with variable aperture, a diaphragm changer, an iris diaphragm or an optoelectronic display can be used here.
  • Although changing devices for apertures with different apertures also have mechanically moving parts, but are much easier than objective changer and therefore can react accordingly faster.
  • However, the use of an iris diaphragm or an optoelectronic display has the advantage that mechanically moving parts can be dispensed with. In addition, their space requirement is much lower, since no space for pivotal movements is necessary.
  • In a third embodiment of the device according to the invention, the telecentric end is designed as a dichroic, with its inner diaphragm area having a diameter of <13 mm, preferably <9 mm and particularly preferably <8 mm for long-wave light and its outer diaphragm area with a diameter> 16 mm, preferably> 13 mm and particularly preferably> 11 mm is permeable to short-wave light.
  • This shows the 4 the detection beam path of the device according to the invention with dichroic Telezentrieblende for the simultaneous determination of the curvature of the cornea of an eye and their registration data. In the detection beam path are starting from the eye 1 , an aperture stop 2 , a lens 3 , a dichroic telecenter screen 4 ' and an image pickup unit 5 arranged, which is connected to a control and evaluation unit, not shown. The dichroic telecenter screen 4 ' is located both for measuring the corneal curvature and for determining the registration data in the detection beam path.
  • According to the 4 is a dichroic telecentric aperture in the detection beam path 4 ' arranged to simultaneously determine the curvature of the cornea of an eye 1 as well as their registration data is suitable. In this case, its inner diaphragm area with a diameter of <8 mm for long-wave light and its outer diaphragm area with a diameter of> 11 mm for short-wave light is permeable, so that both the central region and peripheral peripheral regions on the image recording unit 5 be imaged.
  • This has the advantage that the image of the eye can be imaged on the one image acquisition unit simultaneously with illumination with collimated, structured light as well as with two-dimensional illumination.
  • However, a simultaneous separation of the image signals is required when simultaneously recording the images taken with different illumination. For this purpose, however, known from the prior art solutions. In addition to a temporal separation, in which, for example, a pulsed illumination is used, also offers a separation of the image information by means of a filter. For this purpose, a filter is used in front of or on the image acquisition unit, which is adapted to the wavelengths of the illumination units used and designed, for example, as a 2-color filter with offset pixels.
  • The particular advantage of this embodiment variant is that the data acquisition can take place at the same time and disturbances caused by eye movements no longer have any influence.
  • According to the invention, the method is used to determine the curvature properties of the cornea and to determine registration data, the image of the central corneal area being telecentric and the outer sclera area being non-telecentric in a sequential manner.
  • In the method according to the invention for the registered determination of the curvature of the cornea of an eye, the eye is illuminated in area by a first illumination source with collimated, structured light or by a second illumination source and the light reflected by the eye is illuminated via an aperture stop, an objective, a telecentric aperture onto an image acquisition unit imaged and transmitted to a control and evaluation unit. According to the invention, depending on the illumination source used Telezentrieblende in the beam path on or swung out of this or their aperture varies or a running as a dichroic Telezentrieblende remains in the beam path.
  • According to a first measurement mode, the eye is illuminated by the first illumination source with collimated, structured light for determining the curvature of the cornea, imaged on the image acquisition unit and transmitted to the control and evaluation unit, wherein the telecentricity aperture located in the beam path has a small aperture. For this purpose, the first illumination source transmits long-wave, preferably infrared, light, wherein the structuring can be effected by wavelength differences, shape differences, screen density differences or intensity differences.
  • In the first measurement mode, including the telecentric imaging of the central corneal region, the opening of the telecentric annulus is adjusted so that only narrow cones of the parallel reflection rays of the structured collimated illumination of the central cornea are allowed to pass through the iris. Thus, the beam path is limited in this mode by the aperture of the telecentric end. The telecentric aperture located in the beam path in this case has an aperture of <13 mm, preferably of <9 mm and particularly preferably of <8 mm.
  • In accordance with a second measurement mode, the eye is illuminated areally by the second illumination source to determine registration data, imaged onto the image acquisition unit and transmitted to the control and evaluation unit, the telecentricity aperture being swung out of the beam path or having a large aperture. For this purpose, the second illumination source emits short-wave, preferably green or blue light.
  • In this second measurement mode, which includes the non-telecentric imaging of the outer sclera area, the aperture of the telecentricity aperture is chosen so large that the marginal rays of the outer area with the extra-corneal structures are still imaged. Thus, the beam path in this mode is limited only by the aperture of the aperture stop. A telecentric aperture located in the beam path has an aperture of> 16 mm, preferably> 13 mm and particularly preferably> 11 mm.
  • According to the invention, corresponding control elements are actuated by the control and evaluation unit for realizing the pivot movement or the diameter variation.
  • The change of the aperture of the telecentric aperture can be done by switching two apertures of different sizes. But it is also possible to use an adjustable telecentric screen such as an iris diaphragm or an optoelectronic display.
  • The image is preferably chromatically corrected for both measurement modes such that the telecentric imaging in the infrared region and the non-telecentric imaging in the green or blue region are optimized.
  • In a particularly advantageous embodiment of the second measurement mode, the eye is illuminated areally by the first illumination source with collimated, structured light and by the second illumination source to determine registration data, imaged onto the image acquisition unit and transmitted to the control and evaluation unit, wherein the Imaging unit both the infrared, as well as the green or blue light imaged, transmitted to the control and evaluation and is evaluated by this. In accordance with the second measuring mode, the telecentric end is swung out of the beam path or has a large aperture.
  • This advantageous embodiment has the advantage that the infrared reflected light can also be evaluated during the non-telecentric recording. It is thus possible, during the determination of the registration data, to compare the alignment with the previously determined image of the central corneal region and, if necessary, to correct or correct it.
  • According to a third measurement mode, the eye is simultaneously illuminated to determine the curvature of the cornea with collimated, structured light and to determine the registration whose images are imaged on the image acquisition unit and transmitted to the control and evaluation unit, wherein the executed as a dichroic Telezentrieblende in Beam path remains. For this purpose, the Telezentrieblende is formed as a dichroic, wherein the inner diaphragm area with a diameter of <13 mm, preferably of <9 mm and more preferably of <8 mm for long-wave light and the outer diaphragm area with a diameter> 16 mm, preferably> 13 mm and particularly preferably> 11 mm is permeable to short-wave light.
  • However, a simultaneous separation of the image signals is required when simultaneously recording the images taken with different illumination. For this purpose, however, known from the prior art solutions. In addition to a temporal separation, in which, for example, a pulsed illumination is used, also offers a separation of the image information by means of a filter. For this purpose, a filter is used in front of or on the image acquisition unit, which is adapted to the wavelengths of the illumination units used and designed, for example, as a 2-color filter with offset pixels.
  • This measuring mode has the advantage that the image of the eye can be imaged on the one image acquisition unit simultaneously with illumination with collimated, structured light as well as with two-dimensional illumination. Thus, the data acquisition can take place at the same time, so that temporal disturbances from z. B. eye movements have no influence.
  • With the invention, a solution for keratometric measuring arrangements is provided with which a registered determination of the curvature of the cornea of an eye is possible. Although sequential images of the different areas of the eye are taken, the very short switching time prevents possible eye movements between the images resulting in erroneous registrations.
  • In the solution according to the invention no large or heavy parts, such as lenses or whole lenses are moved. Thus, the switching can be done correspondingly faster for the sequentially recorded shots.
  • If a changing device is used for apertures with different apertures, while it is not possible to dispense with mechanically moving parts, such changers are much easier than objective changer and can therefore respond correspondingly faster.
  • However, the use of an iris diaphragm or an optoelectronic display has the advantage that mechanically moving parts can be dispensed with. In addition, their space requirement is much lower, since no space for pivotal movements is necessary. The overall arrangement can be made more compact and cheaper. By eliminating mechanically moving parts also reduces their susceptibility to failure.
  • The main advantage of the invention lies in the fact that the time between recording of registration and measurement image is substantially reduced. When using the wavelength separation, even a simultaneous recording and recording image can take place.
  • QUOTES INCLUDE IN THE DESCRIPTION
  • This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.
  • Cited patent literature
    • US 4685140 A [0007]
    • US 4660946 A [0008]
    • US 6575573 B2 [0009]
    • US 6692126 B1 [0009]
    • DE 102011102355 [0010]
    • DE 19726291 A1 [0012]
    • DE 19636472 A1 [0012]
    • US 6702806 B2 [0014]
    • US 7815631 B2 [0014]

Claims (22)

  1. Device for the registered determination of the curvature of the cornea of an eye, comprising a first illumination source for collimated, structured illumination and a second illumination source for planar illumination of an eye, a detection beam path, in which, starting from the eye, an aperture stop, an objective, a telecentric aperture and an image acquisition unit are arranged are, as well as a control and evaluation unit, which has connections to the two illumination sources and the image pickup unit, characterized in that the telecentric screen is designed to be pivotable or variable as a dichroic or the aperture.
  2. Apparatus according to claim 1, characterized in that the first illumination source for collimated, structured illumination based on long-wave, preferably infrared light.
  3. Apparatus according to claim 1, characterized in that the second illumination source for flat illumination of an eye based on short-wave, preferably green or blue light.
  4. Apparatus according to claim 1, characterized in that the control and evaluation unit has additional connections to adjusting elements, which are provided for the realization of the pivoting movement or the diameter variation.
  5. Apparatus according to claim 1, characterized in that the image recording unit is designed so that both central, telecentric images of the cornea, as well as non-telecentric images of the outer sclera can be realized at different wavelengths of the illumination light.
  6. Apparatus according to claim 1, characterized in that the aperture stop has an aperture of 10 mm to 25 mm, preferably up to 20 mm and particularly preferably up to 15 mm.
  7. Device according to at least one of the preceding claims, characterized in that the pivotable Telezentrieblende has an aperture of <13 mm, preferably of <9 mm and more preferably of <8 mm.
  8. Device according to at least one of the preceding claims, characterized in that the Telezentrieblende is designed as a dichroic, wherein the inner diaphragm area with a diameter of <13 mm, preferably of <9 mm and more preferably of <8 mm for long-wave light and the outer diaphragm area with a diameter> 16 mm, preferably> 13 mm and particularly preferably> 11 mm is permeable to short-wave light.
  9. Device according to at least one of the preceding claims, characterized in that the Telezentrieblende is formed so that their smallest aperture opening <13 mm, preferably <9 mm and more preferably <8 mm or its largest aperture> 16 mm, preferably> 13 mm and more preferably> 11 mm.
  10. Device according to at least one of the preceding claims, characterized in that the Telezentrieblende is designed as a panel change unit, as an iris diaphragm or as an opto-electronic display.
  11. A method for the registered determination of the curvature of the cornea of an eye, in which the eye is flatly illuminated by a first illumination source with collimated, structured light or by a second illumination source and the light reflected by the eye via an aperture stop, an objective, a telecentric aperture on an image acquisition unit is imaged and transmitted to a control and evaluation unit, characterized in that depending on the illumination source used, the telecentric aperture in the beam path or swung out of this or the aperture is varied or a running as a dichroic Telezentrieblende remains in the beam path.
  12. A method according to claim 11, characterized in that the eye for determining the curvature of the cornea illuminated by the first illumination source with collimated, structured light whose image is imaged on the image pickup unit and transmitted to the control and evaluation unit, which located in the beam path Telezentrieblende has a small aperture.
  13. Method according to claims 11 and 12, characterized in that the first illumination source emits long-wave, preferably infrared light and the structuring is effected by wavelength differences, shape differences, screen density differences or intensity differences.
  14. Method according to claims 11 to 13, characterized in that the telecentric aperture located in the beam path has an aperture of <13 mm, preferably of <9 mm and particularly preferably of <8 mm.
  15. A method according to claim 11, characterized in that the eye for determining the registration of the second illumination source illuminated surface, the image of which is imaged on the image pickup unit and transmitted to the control and evaluation, wherein the telecentric end is swung out of the beam path and has a large aperture.
  16. A method according to claim 15, characterized in that the second illumination source emits short-wave, preferably green or blue light.
  17. Method according to claims 15 and 16, characterized in that the telecentric aperture located in the beam path has an aperture> 16 mm, preferably> 13 mm and particularly preferably> 11 mm.
  18. Method according to claims 11 to 17, characterized in that corresponding control elements are actuated by the control and evaluation unit for realizing the pivot movement or the diameter variation.
  19. Method according to claims 11 to 18, characterized in that for determining the registration, the eye is illuminated both from the first illumination source with collimated, structured light and from the second illumination source, is imaged onto the image acquisition unit and transmitted to the control and evaluation unit , wherein imaged on the image pickup unit, both the infrared, and the green or blue light, transmitted to the control and evaluation and is evaluated by this.
  20. A method according to claim 19, characterized in that the Telzentrieblende is swung out of the beam path or has a large aperture.
  21. A method according to claim 11, characterized in that the eye for determining the curvature of the cornea illuminated with collimated, structured light and for determining the registration area, whose images are imaged on the image pickup unit and transmitted to the control and evaluation unit, which as Dichroit executed telecentric screen remains in the beam path.
  22. A method according to claim 21, characterized in that the executed as a dichroic Telezentrieblende an inner aperture region having a diameter of <13 mm, preferably of <9 mm and particularly preferably of <8 mm, the long-wavelength light and an outer aperture region with a diameter > 16 mm, preferably> 13 mm and particularly preferably> 11 mm, which is permeable to short-wave light.
DE201210019468 2012-09-28 2012-09-28 Device for determining cornea curvature of eye, has image recording unit and control and evaluation unit which is connected to illumination source and image pickup unit, so that telecentric aperture of swivel is varied Pending DE102012019468A1 (en)

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DE19636472A1 (en) 1996-09-07 1998-03-12 Zeiss Carl Jena Gmbh Ophthalmometer for measuring eye cornea curvature
DE19726291A1 (en) 1996-09-07 1998-12-24 Zeiss Carl Jena Gmbh keratometric arrangement
US6575573B2 (en) 2001-10-17 2003-06-10 Carl Zeiss Ophthalmic Systems, Inc. Method and apparatus for measuring a corneal profile of an eye
US6702806B2 (en) 2000-04-19 2004-03-09 Alcon, Inc. Eye registration and astigmatism alignment control systems and method
US7815631B2 (en) 2004-11-30 2010-10-19 Alcon Refractivehorizons, Inc. Eye registration system for refractive surgery and associated methods
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US4660946A (en) 1981-09-21 1987-04-28 Canon Kabushiki Kaisha Cornea shape measuring method and apparatus
US4685140A (en) 1984-06-26 1987-08-04 Kera Corporation Keratograph autoscanner system
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DE102014210787A1 (en) * 2014-06-05 2015-12-17 Carl Zeiss Meditec Ag Distance-compensated measuring device for topographical and keratometric measurements on the eye

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