Claims
- 1. A method of quantifying the extent a cataract impairs vision in an eye having a pupil, an ocular lens, and a retina, said method comprising:
illuminating a localized region of said retina such that light is reflected from said localized region and is transmitted through said ocular lens, a portion of said reflected light being scattered by said cataract associated with said ocular lens; collecting light reflected from said localized region of said retina; and measuring the amount of scatter so as to quantify the extent said scatter impairs vision of said eye.
- 2. The method of claim 1, wherein quantifying the amount of scatter comprises directing said collected light onto a light-sensitive detector having an output indicative of light intensity incident thereon.
- 3. The method of claim 2, comprising forming an optical image of said ocular lens on said light-sensitive detector.
- 4. The method of claim 3, wherein the contrast of said optical image is increased by reducing said localized region of said retina that is illuminated.
- 5. The method of claim 4, wherein said localized region that is illuminated comprises region between about 0.05 and 0.3 millimeter (mm) in size.
- 6. The method of claim 2, further comprising computing a figure of merit based on said output from said light-sensitive detector to assess the extent said cataract impairs vision.
- 7. The method of claim 2, wherein said light-sensitive detector has an electrical output indicative of light intensity incident thereon, and said quantifying the amount of scatter comprises processing said electrical output.
- 8. The method of claim 6, further comprising forming an optical image of said cataract on said light-sensitive detector and displaying an electronic image of said eye on an electronic display using said output from said light-sensitive detector.
- 9. The method of claim 8, wherein said electronic display is positioned so as to be visible by a patient while said optical image of said eye is being formed on said light-sensitive detector.
- 10. The method of claim 8, wherein said patient views said electronic image on said display while said optical image is being formed on said light-sensitive detector.
- 11. The method of claim 8, wherein relative amounts of scatter are summed for different portions of said electronic image.
- 12. The method of claim 11, wherein said different portions of said electronic image include substantially concentric circles centered within said pupil.
- 13. The method of claim 12, further comprising computing a value for a figure of merit that includes scaling the contribution of scattered light associated with a region of said pupil by a factor that depends on proximity to a center of said pupil.
- 14. A method of imaging cataracts in an eye having a cornea, an ocular lens, and a retina, said method comprising:
holding an assembly comprising a light source, imaging optics, and an optical detector array in place by hand a distance from said eye; illuminating a localized region of said retina with light from said light source such that at least a portion of said light is reflected from said localized region of said retina through said ocular lens; collecting light reflected from said localized region of said retina with an optical element; with said imaging optics, forming an optical image of said cataract on said optical detector array so as to produce an electronic image of said cataract; and displaying said electronic image of said cataract on a display.
- 15. The method of claim 14, wherein said patient is shown said electronic image of said eye when said assembly is held in place close to said eye to capture said electronic image of said cataract.
- 16. The method of claim 15, wherein said electronic image is shown to said patient substantially simultaneously to said formation of said optical image on said optical detector array.
- 17. The method of claim 14, further comprising reducing reflection from said cornea by providing polarization filtering.
- 18. The method of claim 17, wherein polarization filtering is provided by a polarization beamsplitter.
- 19. The method of claim 18, wherein polarization filtering is provided by a polarizer positioned between said beamsplitter and a source of light for illuminating said eye and an analyzer positioned between said beamsplitter and said optical detector array.
- 20. The method of claim 14, comprising reducing the collection of rays scattered off said cataract by said imaging optics by selecting said imaging optics to have a small aperture.
- 21. The method of claim 20, comprising selecting imaging optics having an aperture between about 10 and 30 millimeters in diameter.
- 22. The method of claim 21, comprising reducing the collection of rays scattered off said cataract by said imaging optics by positioning said imaging optics so as to provide an optical path length from said eye to said second imaging optics between about 100 and 400 millimeters.
- 23. An apparatus for imaging a cataract in an eye that includes a cornea, a pupil, a lens, and a retina, said apparatus comprising:
a light source; a first optical path from said light source to said eye; beam-shaping optics located in said first optical path so as to receive light emitted by said light source and direct it into the eye and onto the retina; an optical sensor positioned in a second optical path from said eye to receive a portion of light from the light source reflected off the retina; and imaging optics located in said second optical path at a position between said eye and said optical sensor so as to image said cataract onto said optical sensor; and a display in communication with said optical sensor to display an image of said eye, wherein said light source is sufficiently small and said beam-shaping optics has a focal length sufficiently large such that light passing through said beam-shaping optics lens illuminates a spot on said retina between about 0.05 to 0.3 millimeters in size.
- 24. The apparatus of claim 23, wherein said light source is between about 0.05 to 1 millimeters in size.
- 25. The apparatus of claim 23, wherein said beam-shaping optics has a focal length between about 15 and 50 millimeters.
- 26. The apparatus of claim 23, wherein said imaging optics has a entrance pupil diameter about equal to said pupil.
- 27. The apparatus of claim 23, wherein said imaging optics has an aperture diameter (in millimeters) within ±10% of a value determined by the following equation:
- 28. The apparatus of claim 23, wherein said imaging optics has a entrance pupil diameter between about 10 and 30 millimeters.
- 29. The apparatus of claim 23, comprising an optical path length from said eye to said imaging optics between about 100 and 400 millimeters.
- 30. The apparatus of claim 23, wherein said light source emits light substantially comprising light invisible to the human eye.
- 31. The apparatus of claim 30, wherein said light source emits infrared light.
- 32. The apparatus of claim 23, wherein said light source comprises a light emitting diode (LED).
- 33. The apparatus of claim 32, wherein said light source comprises an infrared light emitting diode.
- 34. The apparatus of claim 23, wherein said display comprises a video monitor.
- 35. The apparatus of claim 23, wherein said display comprises a computer screen.
- 36. The apparatus of claim 23, wherein said light source, said beam-shaping optics, said optical sensor, and said imaging optics are included in an optical assembly separated from and movable in relation to said display.
- 37. The apparatus of claim 36, wherein said assembly is between about ¼ and 2 pounds in weight.
- 38. The apparatus of claim 23, further comprising a beamsplitter in said first and second optical paths.
RELATED APPLICATION
[0001] This application claims priority under 35 U.S.C. §119(e) from U.S. Provisional Patent Application No. 60/307,272, filed Jul. 23, 2001, entitled “Instrument and Method for Examining and Quantifying Cataracts.”
Provisional Applications (1)
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Number |
Date |
Country |
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60307272 |
Jul 2001 |
US |