Compact ocular measuring system

• US 6,007,204 A
• Filed: 06/03/1998
• Issued: 12/28/1999
• Est. Priority Date: 06/03/1998
• Status: Expired due to Term

• Current Assignee: Welch Allyn Incorporated
• Original Assignee: Welch Allyn Incorporated
• Inventors: Fahrenkrug, Corinn C., Cuipylo, William N., Haines, Howard A. III, Kugler, Andrew J., Goldfain, Ervin, Perkins, David G.
• Primary Examiner(s): MANUEL, GEORGE C
• Application Number:
  US09/089,807
• Time in Patent Office: 573 Days
• Field of Search: 351/205, 351/211, 351/212, 351/219, 351/221, 351/246, 351/247, 356/121, 356/122, 356/123
• US Class Current: 351/221
• CPC Class Codes: A61B 3/1015 for wavefront analysis

Abstract

Apparatus for determining refractive aberrations of the eye of a patient includes an instrument housing having a light source for projecting a substantially focused beam of light at the back of the eye of a patient, said substantially focused beam acting as a secondary source for a return light path of a fonned outgoing wavefront exiting said eye. An electronic sensor is disposed along said light return path, said electronic sensor having a light detecting surface disposed perpendicular to said return light path, and at least one microoptics array disposed between the electronic sensor and the eye along said return light path. The microoptics array includes plurality of lenslets disposed in a plane perpendicular to said light return path and positioned relative to said electronic sensor so as to substantially focus incremental portions of the outgoing wavefront onto the light detecting surface such that the deviations in the positions of the substantially focused portions impinging on said light detecting surface can be measured so as to determine aberrations of said wavefront. Preferably, at least one pair of conjugate lenses is disposed along said return light path and positioned between said eye and the microoptics array, the lenses of said conjugate pair having unequal focal lengths to allow the device to be used at an effective working distance from a patient

Claims

1. A compact apparatus for determining refractive aberrations of the eye, said apparatus comprising:

a hand-held housing;

illumination means including at least one source of illumination disposed in said housing for projecting a beam of light into the eye of a patient along an illumination axis, said beam forming a secondary source on the back of the eye for a return light path of an outgoing generated wavefront from said eye;

measurement means disposed in said housing including light sensing means disposed along said light return path, said light sensing means including a light detection surface;

at least one microoptics array disposed between said electronic sensor and said eye along said return light path, said microoptics array comprising a plurality of lenslets planarly disposed, said plurality of lenslets and said light detection surface being arranged parallel to each other and perpendicularly to said light return path, said microoptics array being positioned relative to said light sensing means so as to substantially focus portions of said formed wavefront onto said light detection surface, said measurement means further including means for detecting deviations in the positions of the substantially focused portions impinging on said light detecting surface so as to determine aberrations of said outgoing wavefront; and

viewing means disposed in said housing for aligning the eye with the illumination axis.

2. Apparatus as recited in claim 1, including at least one pair of conjugate lenses disposed along said return light path and positioned between said eye and said at least one microoptics array to provide an effective working distance between said housing and an eye of a patient.

3. Apparatus as recited in claim 2, wherein said at least one pair of conjugate lenses include lenses having different effective focal lengths.

4. Apparatus as recited in claim 1, wherein said light source is disposed substantially orthogonal to said portion of said return light path.

5. Apparatus as recited in claim 2, wherein said working distance is in a range of approximately 1 to approximately 80 cm between said housing and an eye being examined.

6. Apparatus as recited in claim 5, wherein said working distance is approximately 40 cm.

7. Apparatus as recited in claim 2, wherein said at least one microoptics array, said at least one pair of conjugate lenses, and said light sensing means are fixedly attached in said housing.

8. Apparatus as recited in claim 7, wherein said illumination means are fixedly attached in said housing.

9. Apparatus as recited in claim 7, wherein said at least one pair of conjugate lenses are disposed in said housing and include a first and a second conjugate lens element, each said lens element being separated from one another by substantially the sum of their respective focal lengths.

10. Apparatus as recited in claim 9, wherein a range of measurable diopters of said eye are manipulated relative to corresponding diopters present at said at least one microoptics array due the generated wavefront passing through said at least one pair of conjugate lenses.

11. Apparatus as recited in claim 10, including a single pair of conjugate lenses in which the first conjugate lens element disposed closer to the eye being examined has an effective focal length which is greater than the effective focal length of the second conjugate lens element.

12. Apparatus as recited in claim 11, wherein the diopters of the formed wavefront presented at said at least one microoptics array are manipulated to be greater than the corresponding measurable diopters of the eye being examined in order to optimize the capability of determining refractive error over a particular diopter range.

13. Apparatus as recited in claim 12, wherein the range of measurable diopters is approximately -20 to +20 diopters.

14. Apparatus as recited in claim 13, wherein the range of measurable diopters is approximately -6 to +6 diopters.

15. Apparatus as recited in claim 2, including position finding means for signaling when an appropriate working distance has been attained between the housing and an eye being examined.

16. Apparatus as recited in claim 15, wherein said position finding means includes an ultrasonic sensor disposed on said housing, said sensor having means for producing at least one audible signal dependent on the distance between said housing and a subject eye.

17. Apparatus as recited in claim 1, wherein said viewing means is disposed along a viewing axis, said viewing axis being arranged at an oblique angle relative to said illumination axis.

18. Apparatus as recited in claim 1, wherein said viewing means includes aiming means, said aiming means including an alignment pattern and means for projecting said alignment pattern along said viewing axis onto the back of the eye.

19. Apparatus as recited in claim 1, wherein said illuminating means includes a monochromatic light source.

20. Apparatus as recited in claim 19, wherein said monochromatic light source is a laser diode.

21. Apparatus as recited in claim 19, wherein said monochromatic light source projects a light beam having a wavelength in the range of approximately 750-850 nm.

22. Apparatus as recited in claim 1, including a beamsplitter disposed along said return light path and said illuminating axis, said beamsplitter allowing a portion of said return light path to be angularly disposed relative to said illuminating axis.

23. Apparatus as recited in claim 1, wherein said lenslets of said array has a pitch between adjacent lenslets which is less than approximately 2 mm.

24. Apparatus as recited in claim 1, including means for defining the portion of said at least one microoptics array onto which said generated wavefront impinges when extended onto said light detecting surface.

25. Apparatus as recited in claim 24, wherein at least one of said lenslets is color encoded.

26. Apparatus as recited in claim 24, including means for masking at least one of said lenslets.

27. Apparatus as recited in claim 24, wherein said at least one of said lenslets is removed in order to provide an alignment orientation of said array for mapping said wavefront.

28. Apparatus as recited in claim 24, wherein the center lenslet is removed from said array.

29. Apparatus as recited in claim 1, including means for manipulating corneal glare from light impinging on said at least one microoptics array along said light return path so as to image glare to a predictable form.

30. Apparatus as recited in claim 29, wherein said corneal glare manipulating means includes means for setting the distance between said at least one microoptics array and the conjugate lens closest to said at least one microoptics array in order to vary the focus thereof.

31. Apparatus as recited in claim 1, wherein said illuminating means includes light adjustment means for varying the position of the formed point source so as to focus onto the back of an aberrated eye.

32. Apparatus as recited in claim 31, wherein said adjustment means includes means for one of either converging and diverging the projected beam of light.

33. Apparatus as recited in claim 1, wherein said viewing means includes means for producing a magnified image.

34. Apparatus as recited in claim 1, including means for fixating the eye being examined.

35. Apparatus as recited in claim 34, wherein said fixating means includes at least one flashing LED disposed along said illuminating axis.

36. Apparatus as recited in claim 35, wherein said fixating means includes an audible signal device disposed in said housing for cuing a subject being examined.

37. Apparatus as recited in claim 35, wherein said fixation means includes at least one still image mounted so as to be viewable by the subject when looking toward said apparatus.

38. Apparatus as recited in claim 37, wherein said position finding means include projection means for projecting at least two images which merge onto a subjects field of view in a recognizable shape at a predetermined working distance.

39. Apparatus as recited in claim 37, wherein said position finding means includes a light emitter and detector oriented angularly relative to each other such that one of the reflected position and intensity of light detected by the detector from said emitter is a known function.

40. Apparatus as recited in claim 37, wherein said position finding means includes at least one wave generator capable of generating a modulated wave reflected toward a subject and detection means for detecting a return wave, said detection means including means for detecting one of the intensity and phase of the return wave as a know function of the distance between said wave generator and the subject.

41. Apparatus as recited in claim 1, including means for displaying data measured by said light detecting surface.

42. A method of measuring refractive eye error, said method comprising:

projecting a beam of light into an eye of interest, said light producing a secondary source and generating a representative wavefront from the eye along a return light path;

aligning said eye with said beam of projected light;

directing said generated wavefront through a pair of conjugate lenses onto at least one microoptics array having a series of planarly disposed lenslet elements, said conjugate lenses and said lenslet array being disposed along said return light path;

substantially focusing incremental portions of said generated wavefront

passing through said lenslet elements onto an imaging substrate; and

measuring the deviations in the incremental portions of said generated wavefront on said imaging substrate so as to measure refractive error in the eye of interest.

43. A method as recited in claim 42, wherein said at least one pair of conjugate lenses include lenses of different effective focal lengths, said method including the step of separating said pair of conjugate lenses along said return light path by substantially the sum of the respective focal lengths of said lenses.

44. A method as recited in claim 43, including the steps of minifying the generated wavefront beam diameter impinging on said at least one microoptics array by using a pair of conjugate lenses in which the conjugate lens closest to the eye of interest has an effective focal length which is greater than the focal length of the remaining conjugate lens so as to increase the optical power of light received by said lenslets.

46. A method as recited in claim 42, wherein said aligning step includes the steps of viewing said eye along a viewing axis which is inclined obliquely relative to said illumination axis and targeting an alignment pattern along said viewing axis in relation to said eye and said projected beam.

45. A compact apparatus for determining refractive aberrations of the eye, said apparatus comprising:

a hand-held housing;

illumination means disposed in said housing for projecting a beam of light into the eye of a patient along an illumination axis, said beam forming a secondary source on the back of the eye for a return light path of a generated wavefront from said eye;

measurement means disposed in said housing including an electronic sensor disposed along said light return path, said electric sensor having an imaging substrate;

alignment means for aligning the eye with the illumination axis, said alignment means including a viewing port arranged obliquely with respect to said illumination means along a viewing axis and means for directing an alignment guide along said viewing axis to said eye;

at least one microoptics array disposed between said electric sensor and said eye along said return light path, said at least one microoptics array comprising a pluarality of lenslets planarly disposed, said plurality of lenslets and said imaging substrate being arranged parallel to each other and perpendicuarly to said light return path, said at least one microoptics array being positioned relative to said electronic sensor so as to substantially focus portions of said formed wavefront onto said imaging substrate, said measurement means further including means for detecting deviations in the positions of the substantially focused portions impinging on said imaging substrate so as to determine aberrations of said outgoing wavefront, and

at least one pair of conjugate lenses disposed along said light return path between the eye of interest and said at least one microoptics array, each of said conjugate lenses having different focal lengths for allowing said housing to be used at a suitable working distance from a patient, said working distance being greater than 1 cm.

47. Apparatus as recited in claim 45, wherein said suitable working distance is in the range of approximately 5 cm to approximately 80 cm.