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WO2012134272A1 - Multifunctional apparatus and method for inspecting an eye - Google Patents

Multifunctional apparatus and method for inspecting an eye Download PDF

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Publication number
WO2012134272A1
WO2012134272A1 PCT/NL2012/050184 NL2012050184W WO2012134272A1 WO 2012134272 A1 WO2012134272 A1 WO 2012134272A1 NL 2012050184 W NL2012050184 W NL 2012050184W WO 2012134272 A1 WO2012134272 A1 WO 2012134272A1
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WO
WIPO (PCT)
Prior art keywords
image
eye
retina
cornea
focus
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/NL2012/050184
Other languages
French (fr)
Inventor
Gerard Cornelis Van Den Eijkel
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L2G BV
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L2G BV
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Filing date
Publication date
Application filed by L2G BV filed Critical L2G BV
Publication of WO2012134272A1 publication Critical patent/WO2012134272A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B3/00—Apparatus for testing the eyes; Instruments for examining the eyes
    • A61B3/10—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions
    • A61B3/14—Arrangements specially adapted for eye photography
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B3/00—Apparatus for testing the eyes; Instruments for examining the eyes
    • A61B3/10—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions
    • A61B3/14—Arrangements specially adapted for eye photography
    • A61B3/15—Arrangements specially adapted for eye photography with means for aligning, spacing or blocking spurious reflection ; with means for relaxing
    • A61B3/152—Arrangements specially adapted for eye photography with means for aligning, spacing or blocking spurious reflection ; with means for relaxing for aligning

Definitions

  • the invention relates to an apparatus for inspecting an eye comprising:
  • an illumination unit to illuminate the eye via the objective lens with an illumination beam.
  • the ophthalmologist may need different ophthalmic inspection apparatus which may be expensive.
  • An object of the invention is to provide an improved apparatus for inspecting an eye. According to a first embodiment of the invention there is provided an apparatus for inspecting an eye comprising:
  • an illumination unit to illuminate the eye via the objective lens with an illumination beam; wherein the apparatus comprises:
  • a projection unit to project a target image on a retina of the eye through a cornea of the eye via the objective lens
  • an imaging unit for receiving an image of the retina or cornea via the objective lens while the eye is illuminated with the illumination unit and/or the target image is projected on the retina with the projection unit, the imaging unit being provided with an image sensor and the imaging unit is constructed and arranged to:
  • the apparatus being provided with a computer system comprising a memory with computer code to calculate an eye power from the image of the target received from the image sensor.
  • the retina may be inspected by using the illumination unit to illuminate the retina and the imaging unit to make an image of the retina on the image sensor.
  • the cornea may be inspected by using the illumination unit to illuminate the cornea and the imaging unit to make an image of the cornea on the image sensor. Whether the retina or the cornea is inspected is dependent on the focus position of the imaging unit.
  • the imaging unit may provided with an in focus image of the target image projected on the retina on the image sensor. This may be done simultaneously with imaging an image on the retina because in both cases the retina is in focus.
  • the eye power may be calculated with computer code provided to a memory of the computer system from the image of the target received from the image sensor.
  • Combining the fundus photography and eye power calculation in one apparatus may offer a cost and space effective solution for the ophthalmologist to inspect an eye.
  • the apparatus combines multiple functions (fundus camera, refractometer and slit-lamp) in one apparatus.
  • the imaging unit may be constructed and arranged to provide a color image of the retina or the cornea on the image sensor.
  • the imaging unit may have wide angle imaging unit comprising a wide angle of acceptance, for example an angle of acceptance larger than 30°, preferably between 45° and 140°.
  • the eye power, cylindrical power and the cylindrical axis of the eye may be measured by the projection unit projecting a target on the retina and the imaging unit making an image of the retina.
  • Combining the functionalities in one apparatus may offer a cost and space effective solution.
  • the mobility is also improved because only one apparatus needs to be transported for an ophthalmologist.
  • the imaging unit may be provided with an image sensor and the imaging unit may be constructed and arranged to provide an in focus image of the target image projected on the retina and an out of focus image from the target image reflected from the cornea on the image sensor. This may be accomplished simultaneously.
  • the apparatus may be provided with an alignment system to align the eye with an optical axis of the objective lens of the apparatus using the out of focus image from the target image reflected from the cornea. By comparing the in focus image of the target image projected on the retina and an out of focus image from the target image reflected from the cornea information with respect to the alignment between the optical axis of the eye and an optical axis of the apparatus may be obtained. The information may be used to adjust the alignment system so as to optimize the alignment of the eye with respect to the apparatus observing the eye.
  • the illumination unit may comprise an infra red illuminator to provide an alignment beam with infra red radiation and a white light illuminator to provide a beam of white light radiation.
  • the alignment beam with infra red radiation may be used to align the eye with the apparatus.
  • the white light illuminator may be used to illuminate the retina with a flash so as to create an image of the retina.
  • the white light illuminator may be used to illuminate the cornea with a flash so as to create an image of the cornea.
  • the apparatus may be provided with a fixation unit for providing a fixation image for the eye via the objective lens.
  • the fixation image may relax the eye by giving it an image projected at infinity with a relatively low intensity so that the pupil of eye opens completely and the eye focuses on the fixation image.
  • the fixation unit may comprise a second lens for adapting the fixation image to the optical strength of the eye. This may be necessary if the eye cannot relax completely by looking at infinity without adjusting the focal position of the eye.
  • a method for inspecting an eye with an apparatus for inspecting an eye comprising:
  • Figure 1 depicts an optical path for an apparatus for inspecting an eye with infra red radiation beams used to align the eye with the apparatus and imaging an image of the alignment result on the image sensor;
  • Figure 2 depicts an optical path for the apparatus for inspecting the eye with the light beams illuminating the retina of the eye through a cornea of the eye with an illumination beam and imaging an image of the retina;
  • Figure 3a depicts an optical path for the apparatus for inspecting the eye with the light beams projecting a target image on the retina through the cornea with a projection beam and imaging an image of the target on the image sensor;
  • Figure 3b depicts an enlargement of figure 3a showing the light beams projecting a target traversing through the cornea
  • Figure 4 depicts an optical path for the apparatus for inspecting the eye with the light beams emanating from a fixation unit for providing a fixation image for the eye.
  • Figure 1 depicts an optical path for an apparatus 2 for inspecting an eye 1 according to a first embodiment of the invention.
  • Infra red (IR) alignment beam 4 may be used to align the eye 1 with the apparatus 2 and to image an image of the alignment result on the image sensor 6 e.g. a charge coupled device (CCD).
  • IR infra red
  • CCD charge coupled device
  • An illumination unit 8 provided to the apparatus 2 comprises a first infra red illuminator 17 e.g. a laser or a light emitting diode (LED) to provide an alignment beam with infra red radiation 4.
  • the illumination unit 8 comprises an IR collimator lens 15, a first hot- cold mirror 13 and an illumination relay lens 1 1 .
  • the alignment beam may be coupled into the objective lens 3.
  • the pupil plane B of the alignment beam may be conjugate with a position behind the pupil of the eye 1 to eliminate glare, for example the position may be 0,2- 5 mm, preferably 1 mm behind the pupil of the eye 1 .
  • the alignment beam 4 illuminates the retina 14 of the eye of a patient via the pupil of the eye.
  • An image of the illuminated retina may be created via the cornea, the objective lens 3 and the image sensor lens 7 on the image sensor 6.
  • the pupil of the eye 1 may be in conjugate relation with the pupil plane A in an imaging branch of the apparatus.
  • the wire grid polarizer 5 works as a mirror for the IR radiation emanating from the illumination unit but the image from the retina traverses through the wire grid polarizer 5 unaltered.
  • the image of the alignment beam on the image sensor 6 may be used to adjust the position of the optical axis of the apparatus 2 with respect to the patients eye 1 and/or to adjust the position of the patients eye 1 with respect to the apparatus 2.
  • the image sensor 6 may be connected to a computer system 18 which may be provided with a memory and processor programmed to determine the alignment and to adjust the apparatus 2 to optimize the alignment.
  • Figure 2 depicts an optical path for the apparatus 2 for inspecting the eye 1 according to an embodiment of the invention.
  • Illumination beam 10 with white light radiation may be used to image an image of the retina of the eye 1 on the image sensor 6 e.g. a (CCD).
  • CCD CCD
  • the illumination unit 8 provided to the apparatus 2 comprises a white light illuminator 21 e.g. a light emitting diode to provide an illumination beam of white light radiation 10.
  • the illumination unit 8 comprises a white light collimator lens 19, the first hot-cold mirror 13 and the illumination relay lens 1 1.
  • the prism e.g. coupling wedge 9 and polarizing beam splitter e.g. wire grid polarizer 5 the illumination beam may be coupled into the objective lens 3.
  • the pupil plane B of the illumination beam may be conjugate with a position behind the pupil of the eye 1 to eliminate glare, for example the position may be 0,2- 5 mm, preferably 1 mm behind the pupil of the eye 1.
  • the illumination beam may illuminate the retina of the eye of the patient via the cornea 16.
  • point source illumination may be used with a diameter of for example 2-4 mm, preferably 3 mm.
  • a wide-angle image of the illuminated retina may be created via the cornea, the objective lens 3 and the image sensor lens 7 on the image sensor 6.
  • the pupil of the eye 1 may be in conjugate relation with the pupil plane A in an imaging unit of the apparatus.
  • the pupil opening may be for example 1 - 2 mm, preferably 1 ,5 mm off axis at the pupil plane A so as to circumvent reflection from the illumination beam.
  • the illuminator may use a short (e.g. 1 - 100 milliseconds) illumination flash to illuminate the retina so that the pupil of the eye 1 has no time to close itself in response to the visible white light.
  • the image of the retina 14 may be processed by the computer system 18.
  • the image sensor lens 7 and the image sensor 6 may be swivelled around a rotation point at fixed position at the pupil of the eye 1. Different portions of the retina 14 can be imaged in this way.
  • the computer system 18 may be used to make a complete image of the retina 14.
  • the focal plane may be adjusted so that the cornea 16 of the eye 1 can be imaged on the image sensor 6.
  • the image sensor lens 7 and the imaging sensor 6 may therefore be moveable and/or provided with moveable lens elements to adjust the focal position.
  • the illuminator may use the short illumination flash to illuminate the cornea so that the pupil of the eye 1 has no time to close itself in response to the visible white light.
  • the image of the cornea may be processed by the computer system 18. In this way with the same apparatus 2 the retina 14 and the cornea 16 may be imaged.
  • the apparatus thereby may function as a good wide-angle fundus photography apparatus and a slit-lamp in one apparatus.
  • Figure 3a depicts an optical path for the apparatus 2 for inspecting the eye 1 according to an embodiment of the invention.
  • the apparatus may be provided with a projection unit 12 to project a target image 14 on the retina through the cornea 16 via the objective lens 3.
  • the projection unit 12 may be provided with a second infra red illuminator e.g. a laser apparatus 29 or light emitting diode for providing a projection beam 10 of infra red IR radiation.
  • the projection unit 12 may be provided with shaping optics 27 e.g. an axicon for shaping the projection beam of infra red radiation into the target image 14 e.g. a ring.
  • a second hot cold mirror 25 may be provided to the projection unit 12 to reflect the infra red projection beam 10 through the projection unit relay lens 23 to the prism e.g. coupling wedge 9 of the apparatus 2.
  • the projection beam 10 may be coupled into the objective lens 3.
  • the pupil plane B of the projection beam may be conjugate with a position behind the pupil of the eye 1 to eliminate glare, for example the position may be 0,2- 5 mm, preferably 1 mm behind the pupil of the eye 1.
  • the projection beam 10 projects the target 14 on the retina of the eye 1 of the patient via the cornea 16.
  • the target image 14 may have a ring shape with a diameter of 1 mm at the cornea 16 which may be projected on the cornea 16 with a diverging beam.
  • the advantage of projecting a ring shape on the cornea 16 may be that this increases the sensitivity for measuring the optical strength of the eye 1. Further, the out of focus ring shape reflection of the cornea 16 may be suitable for alignment purposes.
  • An in-focus image of the target projected on the retina may be created via the cornea 16, the objective lens 3 and the image sensor lens 7 on the image sensor 6 e.g. CCD.
  • the pupil of the eye 1 may be in conjugate relation with the pupil plane A of the apparatus.
  • An out of focus image of the target projected on the cornea 16 may be also projected on the image sensor 6 via the objective lens 3 and the image sensor lens 7.
  • the out of focus image of the target image on the cornea 16 and the in-focus image of the target 14 on the retina may give information of the alignment of the eye 1 with respect to the apparatus 2 and the position of the eye with respect to the apparatus may be adjusted to improve the alignment.
  • the image sensor 6 may be connected to a computer system 18 which may be provided with a memory and processor programmed to process the in-focus and out-of-focus images so as to determine the relative position and to adjust the apparatus 2 to optimize the alignment.
  • a computer system 18 which may be provided with a memory and processor programmed to process the in-focus and out-of-focus images so as to determine the relative position and to adjust the apparatus 2 to optimize the alignment.
  • the computer 18 may be programmed with computer code:
  • the memory of the computer system 18 may be provided with computer code to calculate an eye power, cylindrical power and the axis of the eye 1 with the image of the target 14 received from the image sensor 6. After the apparatus and the eye are correctly aligned the computer 18 may be used to calculate the eye power, cylindrical power and the axis of the eye 1. This information may be used to determine what glasses the patient needs to correct his eye 1.
  • the memory of the computer system 18 may be provided with computer code to calculate one or more of an eye power, cylindrical power and the axis e.g. the cylindrical axis of the eye 1 with the image of the target 14 received form the image sensor 6.
  • the computer may for this purpose be operably connectable with the image sensor.
  • the apparatus in this way additionally functions as a good refractometer.
  • Figure 4 depicts an optical path for the apparatus 2 for inspecting the eye 1 according to an embodiment of the invention with the light beams emanating from a fixation unit 36 for providing a fixation image 35 for the eye.
  • the fixation unit 36 may be provided with a fixation illumination 37, e.g. a light emitting diode to illuminate the fixation image.
  • the eye may look at the fixation image 35 and this may relax the eye 1 and provide a focussing point for the eye 1.
  • the fixation unit 36 may be provided with a mirror 33 and a fixation focus lens 31.
  • the fixation focus lens 31 may be used to adopt the fixation image 37 to the optical strength of the eye 1.
  • the image 35 may be adopted with the fixation lens to a strength of -5 to 5 dioptre of the eye 1.
  • the fixation image 37 may be coupled into the objective lens e.g. objective lens 3 to provide an image to the eye 1.
  • optical components may refer to any one or combination of various types of optical components, including refractive and reflective optical components.
  • the invention may relate to:
  • An apparatus for inspecting an eye comprising:
  • a projection unit to project a target image on a retina of the eye through a cornea of the eye via the objective lens
  • the imaging unit for receiving an image of the retina or cornea via the objective lens while the target image may be projected on the retina with the projection unit.
  • the imaging unit may be provided with an image sensor and the imaging unit may be constructed and arranged to provide an in focus image of the target image projected on the retina and an out of focus image from the target image reflected from the cornea on the image sensor.
  • the apparatus may be provided with a computer system comprising a memory with computer code to calculate an eye power from the image of the target received from the image sensor. An eye power, cylindrical power and/or cylindrical axis of the eye may be calculated as well.
  • the apparatus may be provided with an alignment system to align the eye with an optical axis of the objective lens of the apparatus using the out of focus image from the target image reflected from the cornea.
  • the invention may relate to an apparatus for inspecting an eye comprising:
  • an illumination unit to illuminate the eye via the objective lens with an illumination beam
  • the illumination unit may comprise a first infra red illuminator to provide an alignment beam with infra red radiation and a white light illuminator to provide a beam of white light radiation.
  • the illumination unit may comprise a first hot-cold mirror to combine the alignment beam of infra red radiation with the beam of white light radiation into the illumination beam.
  • the image sensor lens and its components may be adjusted so that the focal plane may be moved from the retina to the cornea and vice versa. In this way the imaging unit may make an image of the retina and/or the cornea.
  • the invention may take the form of a computer program containing one or more sequences of machine-readable instructions describing a method as disclosed above, or a data storage medium (e.g. semiconductor memory, magnetic or optical disk) having such a computer program stored therein.
  • a data storage medium e.g. semiconductor memory, magnetic or optical disk

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Abstract

The invention relates to a multi-functional (wide-angle fundus camera, refractometer and slit-lamp) apparatus for inspecting an eye 1 comprising an objective lens 3 and an illumination unit 17, 21, 19, 15, 1 1, 13 to illuminate a retina 14through a cornea 16 of the eye via the objective lens with an illumination beam. The apparatus may have a projection unit 23, 25, 27, 29 to project a target image on the retina 14 through the cornea 16 via the objective lens. The apparatus may have an imaging unit 7 for receiving a wide-angle image from the retina and/or cornea via the objective lens while the eye is illuminated with the illumination unit and/or the target image is projected on the retina with the projection unit.

Description

Title: Mutlifunctional apparatus and method for inspecting an eye
The invention relates to an apparatus for inspecting an eye comprising:
an objective lens; and,
an illumination unit to illuminate the eye via the objective lens with an illumination beam.
There may be a need for a cost-effective method for inspecting the retina and cornea of the eye. Further, there may be a need for a cost-effective method to measure the eye power, cylindrical power and/or cylindrical axis of the eye. The inspection of the retina and the cornea and the measurement of the eye power, cylindrical power and/or the cylindrical axis of the eye may be accomplished with different ophthalmic inspection apparatus.
Therefore the ophthalmologist may need different ophthalmic inspection apparatus which may be expensive.
An object of the invention is to provide an improved apparatus for inspecting an eye. According to a first embodiment of the invention there is provided an apparatus for inspecting an eye comprising:
an objective lens; and,
an illumination unit to illuminate the eye via the objective lens with an illumination beam; wherein the apparatus comprises:
a projection unit to project a target image on a retina of the eye through a cornea of the eye via the objective lens; and,
an imaging unit for receiving an image of the retina or cornea via the objective lens while the eye is illuminated with the illumination unit and/or the target image is projected on the retina with the projection unit, the imaging unit being provided with an image sensor and the imaging unit is constructed and arranged to:
focus an in-focus fundus image or in-focus cornea image depending on focus position on the image sensor; and/or,
focus an in focus image of the target image projected on the retina on the image sensor, the apparatus being provided with a computer system comprising a memory with computer code to calculate an eye power from the image of the target received from the image sensor. The retina may be inspected by using the illumination unit to illuminate the retina and the imaging unit to make an image of the retina on the image sensor. The cornea may be inspected by using the illumination unit to illuminate the cornea and the imaging unit to make an image of the cornea on the image sensor. Whether the retina or the cornea is inspected is dependent on the focus position of the imaging unit. The imaging unit may provided with an in focus image of the target image projected on the retina on the image sensor. This may be done simultaneously with imaging an image on the retina because in both cases the retina is in focus. To improve contrast both may be done alternatingly such that making an image of the retina or cornea and providing an image of the target on the retina are done during separate steps. The eye power may be calculated with computer code provided to a memory of the computer system from the image of the target received from the image sensor. Combining the fundus photography and eye power calculation in one apparatus may offer a cost and space effective solution for the ophthalmologist to inspect an eye. The apparatus combines multiple functions (fundus camera, refractometer and slit-lamp) in one apparatus. The imaging unit may be constructed and arranged to provide a color image of the retina or the cornea on the image sensor. The imaging unit may have wide angle imaging unit comprising a wide angle of acceptance, for example an angle of acceptance larger than 30°, preferably between 45° and 140°.
Further the eye power, cylindrical power and the cylindrical axis of the eye may be measured by the projection unit projecting a target on the retina and the imaging unit making an image of the retina. Combining the functionalities in one apparatus may offer a cost and space effective solution. The mobility is also improved because only one apparatus needs to be transported for an ophthalmologist.
The imaging unit may be provided with an image sensor and the imaging unit may be constructed and arranged to provide an in focus image of the target image projected on the retina and an out of focus image from the target image reflected from the cornea on the image sensor. This may be accomplished simultaneously. The apparatus may be provided with an alignment system to align the eye with an optical axis of the objective lens of the apparatus using the out of focus image from the target image reflected from the cornea. By comparing the in focus image of the target image projected on the retina and an out of focus image from the target image reflected from the cornea information with respect to the alignment between the optical axis of the eye and an optical axis of the apparatus may be obtained. The information may be used to adjust the alignment system so as to optimize the alignment of the eye with respect to the apparatus observing the eye.
The illumination unit may comprise an infra red illuminator to provide an alignment beam with infra red radiation and a white light illuminator to provide a beam of white light radiation. The alignment beam with infra red radiation may be used to align the eye with the apparatus. The white light illuminator may be used to illuminate the retina with a flash so as to create an image of the retina. The white light illuminator may be used to illuminate the cornea with a flash so as to create an image of the cornea.
The apparatus may be provided with a fixation unit for providing a fixation image for the eye via the objective lens. The fixation image may relax the eye by giving it an image projected at infinity with a relatively low intensity so that the pupil of eye opens completely and the eye focuses on the fixation image. The fixation unit may comprise a second lens for adapting the fixation image to the optical strength of the eye. This may be necessary if the eye cannot relax completely by looking at infinity without adjusting the focal position of the eye.
According to a further embodiment of the invention a method for inspecting an eye with an apparatus for inspecting an eye is provided, comprising:
illuminating the eye with an illumination beam;
projecting a target image on a retina of the eye through a cornea of the eye; and, imaging an image of the retina or cornea depending on focus position while the eye is illuminated with the illumination beam and/or the target image is projected on the retina and calculating an eye power using the image of the target image projected on the retina with a computer system of the apparatus. Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:
Figure 1 depicts an optical path for an apparatus for inspecting an eye with infra red radiation beams used to align the eye with the apparatus and imaging an image of the alignment result on the image sensor;
Figure 2 depicts an optical path for the apparatus for inspecting the eye with the light beams illuminating the retina of the eye through a cornea of the eye with an illumination beam and imaging an image of the retina;
Figure 3a depicts an optical path for the apparatus for inspecting the eye with the light beams projecting a target image on the retina through the cornea with a projection beam and imaging an image of the target on the image sensor;
Figure 3b depicts an enlargement of figure 3a showing the light beams projecting a target traversing through the cornea; and,
Figure 4 depicts an optical path for the apparatus for inspecting the eye with the light beams emanating from a fixation unit for providing a fixation image for the eye. Figure 1 depicts an optical path for an apparatus 2 for inspecting an eye 1 according to a first embodiment of the invention. Infra red (IR) alignment beam 4 may be used to align the eye 1 with the apparatus 2 and to image an image of the alignment result on the image sensor 6 e.g. a charge coupled device (CCD).
An illumination unit 8 provided to the apparatus 2 comprises a first infra red illuminator 17 e.g. a laser or a light emitting diode (LED) to provide an alignment beam with infra red radiation 4. The illumination unit 8 comprises an IR collimator lens 15, a first hot- cold mirror 13 and an illumination relay lens 1 1 . Via a prism e.g. coupling wedge 9 and a polarizing beam splitter e.g. wire grid polarizer 5 the alignment beam may be coupled into the objective lens 3. The pupil plane B of the alignment beam may be conjugate with a position behind the pupil of the eye 1 to eliminate glare, for example the position may be 0,2- 5 mm, preferably 1 mm behind the pupil of the eye 1 . Subsequently, the alignment beam 4 illuminates the retina 14 of the eye of a patient via the pupil of the eye.
An image of the illuminated retina may be created via the cornea, the objective lens 3 and the image sensor lens 7 on the image sensor 6. The pupil of the eye 1 may be in conjugate relation with the pupil plane A in an imaging branch of the apparatus. The wire grid polarizer 5 works as a mirror for the IR radiation emanating from the illumination unit but the image from the retina traverses through the wire grid polarizer 5 unaltered. The image of the alignment beam on the image sensor 6 may be used to adjust the position of the optical axis of the apparatus 2 with respect to the patients eye 1 and/or to adjust the position of the patients eye 1 with respect to the apparatus 2. The image sensor 6 may be connected to a computer system 18 which may be provided with a memory and processor programmed to determine the alignment and to adjust the apparatus 2 to optimize the alignment.
Figure 2 depicts an optical path for the apparatus 2 for inspecting the eye 1 according to an embodiment of the invention. Illumination beam 10 with white light radiation may be used to image an image of the retina of the eye 1 on the image sensor 6 e.g. a (CCD).
The illumination unit 8 provided to the apparatus 2 comprises a white light illuminator 21 e.g. a light emitting diode to provide an illumination beam of white light radiation 10. The illumination unit 8 comprises a white light collimator lens 19, the first hot-cold mirror 13 and the illumination relay lens 1 1. Via the prism e.g. coupling wedge 9 and polarizing beam splitter e.g. wire grid polarizer 5 the illumination beam may be coupled into the objective lens 3. The pupil plane B of the illumination beam may be conjugate with a position behind the pupil of the eye 1 to eliminate glare, for example the position may be 0,2- 5 mm, preferably 1 mm behind the pupil of the eye 1. Subsequently, the illumination beam may illuminate the retina of the eye of the patient via the cornea 16. Referring to the pupil plane B of the illumination beam, point source illumination may be used with a diameter of for example 2-4 mm, preferably 3 mm.
A wide-angle image of the illuminated retina may be created via the cornea, the objective lens 3 and the image sensor lens 7 on the image sensor 6. The pupil of the eye 1 may be in conjugate relation with the pupil plane A in an imaging unit of the apparatus. The pupil opening may be for example 1 - 2 mm, preferably 1 ,5 mm off axis at the pupil plane A so as to circumvent reflection from the illumination beam. The illuminator may use a short (e.g. 1 - 100 milliseconds) illumination flash to illuminate the retina so that the pupil of the eye 1 has no time to close itself in response to the visible white light. The image of the retina 14 may be processed by the computer system 18.
To get a complete image of the retina 14 the image sensor lens 7 and the image sensor 6 may be swivelled around a rotation point at fixed position at the pupil of the eye 1. Different portions of the retina 14 can be imaged in this way. The computer system 18 may be used to make a complete image of the retina 14.
By changing the focal position of the imaging unit the focal plane may be adjusted so that the cornea 16 of the eye 1 can be imaged on the image sensor 6. The image sensor lens 7 and the imaging sensor 6 may therefore be moveable and/or provided with moveable lens elements to adjust the focal position. The illuminator may use the short illumination flash to illuminate the cornea so that the pupil of the eye 1 has no time to close itself in response to the visible white light. The image of the cornea may be processed by the computer system 18. In this way with the same apparatus 2 the retina 14 and the cornea 16 may be imaged. The apparatus thereby may function as a good wide-angle fundus photography apparatus and a slit-lamp in one apparatus.
Figure 3a depicts an optical path for the apparatus 2 for inspecting the eye 1 according to an embodiment of the invention. The apparatus may be provided with a projection unit 12 to project a target image 14 on the retina through the cornea 16 via the objective lens 3. The projection unit 12 may be provided with a second infra red illuminator e.g. a laser apparatus 29 or light emitting diode for providing a projection beam 10 of infra red IR radiation. The projection unit 12 may be provided with shaping optics 27 e.g. an axicon for shaping the projection beam of infra red radiation into the target image 14 e.g. a ring. A second hot cold mirror 25 may be provided to the projection unit 12 to reflect the infra red projection beam 10 through the projection unit relay lens 23 to the prism e.g. coupling wedge 9 of the apparatus 2. Via polarizing beam splitter e.g. wire grid polarizer 5 the projection beam 10 may be coupled into the objective lens 3. The pupil plane B of the projection beam may be conjugate with a position behind the pupil of the eye 1 to eliminate glare, for example the position may be 0,2- 5 mm, preferably 1 mm behind the pupil of the eye 1. Subsequently, the projection beam 10 projects the target 14 on the retina of the eye 1 of the patient via the cornea 16. The target image 14 may have a ring shape with a diameter of 1 mm at the cornea 16 which may be projected on the cornea 16 with a diverging beam. The advantage of projecting a ring shape on the cornea 16 (see figure 3b) may be that this increases the sensitivity for measuring the optical strength of the eye 1. Further, the out of focus ring shape reflection of the cornea 16 may be suitable for alignment purposes.
An in-focus image of the target projected on the retina may be created via the cornea 16, the objective lens 3 and the image sensor lens 7 on the image sensor 6 e.g. CCD. The pupil of the eye 1 may be in conjugate relation with the pupil plane A of the apparatus. An out of focus image of the target projected on the cornea 16 may be also projected on the image sensor 6 via the objective lens 3 and the image sensor lens 7. The out of focus image of the target image on the cornea 16 and the in-focus image of the target 14 on the retina may give information of the alignment of the eye 1 with respect to the apparatus 2 and the position of the eye with respect to the apparatus may be adjusted to improve the alignment. The image sensor 6 may be connected to a computer system 18 which may be provided with a memory and processor programmed to process the in-focus and out-of-focus images so as to determine the relative position and to adjust the apparatus 2 to optimize the alignment. For a good alignment the computer 18 may be programmed with computer code:
- to check whether the imaged target ring of the retina and the imaged target ring of the cornea may be concentric; and,
- to check whether the imaged target ring of the retina and its ghost images caused by internal reflections may have an equal size and intensity.
The memory of the computer system 18 may be provided with computer code to calculate an eye power, cylindrical power and the axis of the eye 1 with the image of the target 14 received from the image sensor 6. After the apparatus and the eye are correctly aligned the computer 18 may be used to calculate the eye power, cylindrical power and the axis of the eye 1. This information may be used to determine what glasses the patient needs to correct his eye 1. The memory of the computer system 18 may be provided with computer code to calculate one or more of an eye power, cylindrical power and the axis e.g. the cylindrical axis of the eye 1 with the image of the target 14 received form the image sensor 6. The computer may for this purpose be operably connectable with the image sensor. The apparatus in this way additionally functions as a good refractometer.
Figure 4 depicts an optical path for the apparatus 2 for inspecting the eye 1 according to an embodiment of the invention with the light beams emanating from a fixation unit 36 for providing a fixation image 35 for the eye. The fixation unit 36 may be provided with a fixation illumination 37, e.g. a light emitting diode to illuminate the fixation image. The eye may look at the fixation image 35 and this may relax the eye 1 and provide a focussing point for the eye 1. The fixation unit 36 may be provided with a mirror 33 and a fixation focus lens 31. The fixation focus lens 31 may be used to adopt the fixation image 37 to the optical strength of the eye 1. For example, the image 35 may be adopted with the fixation lens to a strength of -5 to 5 dioptre of the eye 1. Via the second hot cold mirror 25, the projection unit relay lens 23, the prism e.g. coupling wedge 9 and the polarizing beam splitter e.g. wire grid polarizer 5 the fixation image 37 may be coupled into the objective lens e.g. objective lens 3 to provide an image to the eye 1.
The terms "radiation" and "beam" used herein encompass all types of
electromagnetic radiation. The term "lens", where the context allows, may refer to any one or combination of various types of optical components, including refractive and reflective optical components.
While specific embodiments of the invention have been described above, it will be appreciated that the invention may be practiced otherwise than as described. For example, the invention may relate to:
An apparatus for inspecting an eye comprising:
an objective lens;
a projection unit to project a target image on a retina of the eye through a cornea of the eye via the objective lens; and,
an imaging unit for receiving an image of the retina or cornea via the objective lens while the target image may be projected on the retina with the projection unit. The imaging unit may be provided with an image sensor and the imaging unit may be constructed and arranged to provide an in focus image of the target image projected on the retina and an out of focus image from the target image reflected from the cornea on the image sensor. The apparatus may be provided with a computer system comprising a memory with computer code to calculate an eye power from the image of the target received from the image sensor. An eye power, cylindrical power and/or cylindrical axis of the eye may be calculated as well. The apparatus may be provided with an alignment system to align the eye with an optical axis of the objective lens of the apparatus using the out of focus image from the target image reflected from the cornea.
The invention may relate to an apparatus for inspecting an eye comprising:
an objective lens;
an illumination unit to illuminate the eye via the objective lens with an illumination beam; and,
an imaging unit for receiving an image of the retina or cornea via the objective lens while the eye may be illuminated with the illumination unit. The illumination unit may comprise a first infra red illuminator to provide an alignment beam with infra red radiation and a white light illuminator to provide a beam of white light radiation. The illumination unit may comprise a first hot-cold mirror to combine the alignment beam of infra red radiation with the beam of white light radiation into the illumination beam. The image sensor lens and its components may be adjusted so that the focal plane may be moved from the retina to the cornea and vice versa. In this way the imaging unit may make an image of the retina and/or the cornea.
The invention may take the form of a computer program containing one or more sequences of machine-readable instructions describing a method as disclosed above, or a data storage medium (e.g. semiconductor memory, magnetic or optical disk) having such a computer program stored therein.
The descriptions above are intended to be illustrative, not limiting. Thus, it will be apparent to one skilled in the art that modifications may be made to the invention as described without departing from the scope of the claims set out below.

Claims

Claims
1. Apparatus for inspecting an eye comprising:
an objective lens; and,
an illumination unit to illuminate the eye via the objective lens with an illumination beam; wherein the apparatus comprises:
a projection unit to project a target image on a retina of the eye through a cornea of the eye via the objective lens; and,
an imaging unit for receiving an image of the retina or cornea via the objective lens while the eye is illuminated with the illumination unit and/or the target image is projected on the retina with the projection unit, the imaging unit being provided with an image sensor and the imaging unit is constructed and arranged to:
focus an in-focus fundus image or in-focus cornea image depending on focus position on the image sensor; and/or,
focus an in focus image of the target image projected on the retina on the image sensor depending on focus position, the apparatus being provided with a computer system comprising a memory with computer code to calculate an eye power from the image of the target received from the image sensor.
2. The apparatus according to claim 1 , wherein the imaging unit is constructed and arranged to provide an out of focus image from the target image reflected from the cornea on the image sensor.
3. The apparatus according to claim 2, wherein the apparatus is provided with an alignment system to align the eye with an optical axis of the objective lens of the apparatus using the out of focus image from the target image reflected from the cornea.
4. The apparatus according to any of the preceding claims, wherein the illumination unit comprises a first infra red illuminator to provide an alignment beam with infra red radiation and a white light illuminator to provide a beam of white light radiation.
5. The apparatus according to claim 4, wherein the illumination unit comprises a first hot-cold mirror to combine the alignment beam of infra red radiation with the beam of white light radiation into the illumination beam.
6. The apparatus according to any of the preceding claims, wherein the projection unit is provided with a second infra red illuminator for providing a projection beam of infra red radiation and shaping optics for shaping the projection beam of infra red radiation into the target image.
7. The apparatus according to claim 6, wherein the second infra red illuminator is 5 provided with a laser apparatus.
8. The apparatus according to claim 6 or 7, wherein the shaping optics is provided with an axicon for shaping the projection beam into the target image.
10 9. The apparatus according to claim 1 , wherein the apparatus is provided with a fixation unit for providing a fixation image for the eye via the objective lens.
10. The apparatus according to claim 9, wherein the fixation unit comprises a second lens for adapting the fixation image to the optical strength of the eye.
15
1 1 . The apparatus according to claim 9 or 10, wherein the fixation unit is provided to the projection unit and the projection beam of infra red radiation and the light rays of the fixation image are combined with a second hot cold mirror provided to the projection unit.
20 12. The apparatus according to any of claims 9 to 1 1 , wherein the illumination beam and/or the projection beam and the rays of the fixation image of the fixation unit are coupled into the objective lens with a prism, preferably a wedge prism.
13. The apparatus according to any of the preceding claims, wherein the computer 25 system comprising a memory with computer code to calculate an eye power, cylindrical power and/or cylindrical axis of the eye from the image of the target received from the image sensor.
14. The apparatus according to claim 1 , wherein the image of the retina and/or the 30 cornea of the eye is projected on the image sensor via an image sensor lens with a pupil stop and the objective lens.
15. The apparatus according to claim 14, wherein the apparatus is provided with a polarizing beam splitter to couple the combined illumination beam into the objective lens
35 between the objective lens and the image sensor lens.
16. The apparatus according to claim 15, wherein the polarizing beam splitter is a wire grid polarizer.
17. The apparatus according to claim 14, wherein the objective lens and the image
5 sensor lens may be adjusted so that the focal plane may be moved from the retina to the cornea.
18. A method for inspecting an eye with an apparatus for observing an eye is provided, comprising:
10 illuminating the eye with an illumination beam;
projecting a target image on a retina of the eye through a cornea of the eye; and, imaging an image of the retina or cornea depending on focus position while the eye is illuminated with the illumination beam and/or the target image is projected on the retina and calculating the eye power using the image of the target image projected on the retina 15 with a computer system of the apparatus.
19. The method according to claim 18, wherein the method comprises imaging an in focus image of the target projected on the retina and an out of focus image from the target image reflected from the cornea on an image sensor.
20
20. The method according to claim 19, wherein the method comprises aligning the eye using an in focus image of the target image projected on the retina and an out of focus image from the target reflected from the cornea.
25 21. The method according to any of claims 18 to 20, wherein the method comprises calculating the eye power, cylindrical power and/or the cylindrical axis of the eye using the image of the target image projected on the retina
PCT/NL2012/050184 2011-03-25 2012-03-23 Multifunctional apparatus and method for inspecting an eye Ceased WO2012134272A1 (en)

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