Instrument for eye examination and method

• US 6,705,726 B2
• Filed: 02/20/2002
• Issued: 03/16/2004
• Est. Priority Date: 02/20/2002
• Status: Active Grant

• Current Assignee: Nidek Company Limited
• Original Assignee: Nidek Company Limited
• Inventors: Tanassi, Cesare, Piermarocchi, Dott. Stefano, Buscemi, Philip M.
• Primary Examiner(s): Manuel, George
• Application Number:
  US10/079,683
• Publication Number:
  US 20030156258A1
• Time in Patent Office: 755 Days
• Field of Search: 351/200, 351/205, 351/206, 351/208, 351/211, 351/212, 351/221, 351/246, 351/239, 351/243
• US Class Current: 351/206
• CPC Class Codes: A61B 3/12 for looking at the eye fundus, e.g. ophthalmoscopes A61B3/13 takes precedence
• CPC Class Codes: A61B 3/145 by video means

Abstract

The present invention relates to a novel instrument for the examination of an eye, namely the retina. The instrument features a LCD display for projection of various types of patterns and stimuli via an optical system onto the retina. The retina can be visualized by live IR image sequences as well as by visible light still frame images. It combines five examination types within one instrument, namely a perimetry examination, a microperimetry examination, a fixation stability examination, a scotoma boundary detection and psychophysical examinations.

Claims

1. An optical instrument for examination of an eye comprising:

a) a light source for producing visible light patterns to be projected on a region of said eye to be examined,

b) an optical system for projecting said light patterns on said region, for illuminating said region, and for producing images of said region, and

c) an electronic camera for producing data signals of said images of said region,

wherein

said light source comprises a LCD display arranged to produce said light patterns, and said optical system is arranged to project the light patterns produced by the LCD display from the LCD display to the region of said eye to be examined.

2. An optical instrument according to claim 1 wherein said region is a part of the retina of said eye.

3. An optical instrument according to claim 1 comprising an IR light source for illuminating said region of said eye via said optical system and an IR-camera for producing data signals of live image sequences produced in said IR camera by said optical system as well as an electronic camera for visible light.

4. An optical instrument according to claim 1 comprising an IR light source for illuminating said region of said eye via said optical system and an IR camera for producing data signals of live image sequences produced in said IR camera by said optical system and wherein said optical system comprises a mirror for reflecting IR illumination light of said IR light source to a front lens of said instrument being directed to the eye to be examined, said mirror defining a central aperture for light from said front lens for an image of said eye region to traverse said mirror without being reflected.

5. An optical instrument according to claim 4 wherein said aperture in said mirror is optically conjugated with the cornea of said eye to be examined.

6. An optical instrument according to claim 4, further comprising a flashing lamp for producing visible flashing light and a cold mirror for coupling said flashing light into an optical path used for said illumination by said IR light source, going to said apertured mirror.

7. An optical instrument according to claim 1 comprising an IR light source for illuminating said region of said eye via said optical system and an IR camera for producing data signals of live image sequences produced in said IR camera by said optical system and wherein said optical system comprises a beam splitter for branching-off an optical side path for said IR-camera from an optical main path for said display.

8. An optical instrument according to claim 1 wherein said optical system comprises a movable mirror for branching-off an optical side path for an electronic camera for visible light.

9. An optical instrument according to claim 8 further comprising a light sensor for calibration of said display, said movable mirror being adapted to reflect light from said display to said light sensor for calibration of said display.

10. An optical instrument according to claim 1 further comprising a computer control system, said computer control system including an autotracking system using a grey scale correlation algorithm for comparing image frames of said electronic camera with respect to a reference frame and detecting image x and y shifts and rotations therein, said computer control system comprising an adaption system for adapting to said image x and y shifts and rotations.

11. An optical instrument according to claim 10 wherein said adaption system can be used to properly locate stimuli on said LCD display in a position conjugated with a retinal area to be stimulated, by using said x and y shifts and rotations of said eye region.

12. An optical instrument according to claim 11 wherein said autotracking system is adapted to perform said grey scale correlation algorithm only in a subframe of said image frames.

13. An optical instrument according to claim 1 further comprising a computer control system, wherein said computer control system is adapted to superpose a graphical visualization of examination results on still frame images.

14. An optical instrument for examination of an eye retina comprising:

a) a light source for producing visible light patterns to be projected on said retina,

b) an optical system for projecting said light patterns on said retina and for producing images of said retina,

c) an electronic camera for producing data signals of said images of said retina, and

d) a computer control system,

wherein said light source is a display being adapted to produce a variety of different patterns of selectable intensity, selectable position and selectable structure,

that said instrument includes an input device whereby a patient can input a reaction during examination, that said instrument includes an IR light source for illuminating said retina via said optical system and that said electronic camera is an IR camera for producing data signals of live image sequences produced in said IR camera by said optical system, and that said instrument is adapted to perform, within one instrument;

i) a perimetry examination in which said display is need to produce a fixation target pattern for eye fixation and light stimuli of fixed but selectable position and selectable intensity for stimulation of the eye, both to be projected on said retina, wherein said input device is used to detect a patient reaction if said patient can see said stimuli;

ii) a microperimetry examination in which said display is used to produce a fixation target pattern for eye fixation and light stimuli of fixed but selectable position and selectable intensity for stimulation of the eye, both to be projected on said retina, wherein said input device is used to detect a patient reaction if said patient can see said stimuli;

iii) a fixation stability examination in which said display is used to produce a fixation target pattern for eye fixation to be projected on said retina, wherein simultaneously said retina is imaged by said live image sequences, wherein said computer control system uses a correlation algorithm to collect fixation position movement data;

iv) a scotoma boundary detection, wherein said display is used to produce moving light stimuli to be projected on said retina, said projected stimuli moving towards a scotoma boundary on said retina, and wherein said input device is used to detect a patient reaction responsive on whether the patient can see said stimuli;

v) or psychophysical examinations wherein said display is used to produce a psychophysical test pattern selectable from a variety of psychophysical test patterns, to be projected on said retina, and wherein said retina is imaged by said live image sequences simultaneously.

15. An optical instrument according to claim 14 wherein said display is a LCD-display.

16. An optical instrument according to claim 15 wherein said optical system comprises a beam splitter for branching-off an optical side path for said IR-camera from an optical main path for said display.

17. An optical instrument according to claim 15 wherein said optical system comprises a movable mirror for branching-off an optical side path for an electronic camera for visible light.

18. An optical instrument according to claim 17 further comprising a light sensor for calibration of said display, said movable mirror being adapted to reflect light from said display to said light sensor for calibration of said display.

19. An optical instrument according to claim 15 wherein said computer control system includes an autotracking system using a grey scale correlation algorithm for comparing image frames of said electronic camera with respect to a reference frame and detecting image x and y shifts and rotations therein, wherein said computer control system comprises an adaption system for adapting to said image x and y shifts and rotations.

20. An optical instrument according to claim 19 wherein said adaption system can be used to properly locate stimuli on said LCD display in a position conjugated with a retinal area to be stimulated, by using said x and y shifts and rotations of said eye region.

21. An optical instrument according to claim 19 wherein said autotracking system is adapted to perform said grey scale correlation algorithm only in a subframe of said image frames and to let a user select said subframe.

22. An optical instrument according to claim 21 wherein said autotracking function can be used in each of said perimetry, microperimetry, fixation stability, scotoma boundary detection, and psychophysical examinations of claim 14.

23. An optical instrument according to claim 15 wherein said computer control system is adapted to superpose a graphical visualization of examination results on still frame images.

24. An optical instrument according to claim 14 further comprising an electronic camera for visible light.

25. An optical instrument according to claim 14 wherein said optical system comprises a mirror for reflecting IR illumination light of said IR light source to a front lens of said instrument being directed to the eye to be examined, said mirror defining a central aperture for light from said front lens for an image of said eye region to traverse said mirror without being reflected.

26. An optical instrument according to claim 25 wherein said aperture in said mirror is optically conjugated with the cornea of said eye to be examined.

27. An optical instrument according to claim 25 further comprising a flashing lamp for producing visible flashing light and a cold mirror for coupling said flashing light into an optical path used for said illumination by said IR light source, going to said apertured mirror.

28. A method of examining an eye comprising the steps of:

a) producing visible light patterns by means of an LCD display,

b) projecting said light patterns from said LCP display to a region of said eye to be examined by means of an optical system,

c) illuminating said region and producing images of said region by means of said optical system, and

d) producing data signals of said images of said region by means of an electronic camera.

29. A method according to claim 28 wherein a grey scale correlation algorithm in an autotracking system of a computer control system is used for comparing image frames of said electronic camera and detecting image shifts therein and an adaption system of said computer control system is used for adapting to said image shifts.

30. A method according to claim 29 wherein said grey scale correlation algorithm is used only in a subframe of said image frames.

31. A method according to claim 28 wherein a computer control system is used to superpose a graphical visualization of examination results on still frame images.

32. A method of examining an eye retina comprising the steps of:

a) producing visible light patterns by means of a light source,

b) projecting said light patterns on said retina of said eye to be examined by means of an optical system,

c) illuminating said region and producing images of said retina by means of said optical system, and

d) producing data signals of said images of said retina by means of an electronic camera,

wherein said light patterns are produced by means of a display of said light source, said display being adapted to produce a variety of different patterns of selectable intensity, selectable position and selectable structure, and wherein an IR light source is used for illuminating said retina via said optical system and said electronic camera is an IR camera and produces data signals of live image sequences produced in said IR camera by said optical system, and wherein an operator can select, using one and the same optical instrument, between the examination types of;

i) a perimetry examination in which said display is used to produce a fixation target pattern for eye fixation and light stimuli of fixed by selectable position and selectable intensity for stimulation of the eye, both to be projected on said retina, wherein an input device is used to detect a patient reaction if said patient can see said stimuli;

ii) a microperimetry examination in which said display is used to produce a fixation target pattern for eye fixation and light stimuli of fixed by selectable position and selectable intensity for stimulation of the eye, both to be projected on said retina, wherein an input device is used to detect a patient reaction if said patient can see said stimuli;

iii) a fixation stability examination in which said display is used to produce a fixation target pattern for eye fixation to be projected on said retina, wherein simultaneously said retina is imaged by said live image sequences, wherein a computer control system uses a correlation algorithm to collect fixation position movement data;

iv) a scotoma boundary detection, wherein said display is used to produce moving light stimuli to be projected on said retina, said projected stimuli moving towards a scotoma boundary on said retina, and wherein said input device is used to detect a patient reaction responsive on whether the patient can see said stimuli;

v) or psychophysical examinations wherein said display is used to produce a psychophysical test pattern selectable from a variety of psychophysical test patterns, to be projected on said retina, and wherein said retina is imaged by said live image sequences simultaneously.

33. A method according to claim 32 wherein a grey scale correlation algorithm in an autotracking system of said computer control system is used for comparing image frames of said electronic camera with a respect to a reference frame and detecting image x and y shifts and rotations therein, and an adaption system of said computer control system is used for adapting to said image x and y shifts and rotations.

34. A method according to claim 33 wherein said adaption system is used to properly locate stimuli on said LCD display in a position conjugated with a retinal area to be stimulated, by using said x and y shifts and rotations of said eye region.

35. A method according to claim 33 wherein said grey scale correlation algorithm is used only in a subframe of said image frames.

36. A method according to claim 33 wherein said autotracking function can be used in each of said perimetry, microperimetry, fixation stability, scotoma boundary detection and psychophysical examinations.

37. A method according to claim 32 wherein said computer control system is used to superpose a graphical visualization of examination results on still frame images.