Tear film measurement

• US 20080316499A1
• Filed: 06/20/2007
• Published: 12/25/2008
• Est. Priority Date: 06/20/2007
• Status: Active Grant

• Current Assignee: TearScience Inc. (Johnson & Johnson)
• Original Assignee: TearScience Inc. (Johnson & Johnson)
• Inventors: Korb, Donald R., Gravely, Benjamin T.
• Granted Patent: US 7,758,190 B2
• Time in Patent Office: Days
• US Class Current: 356/503
• CPC Class Codes: A61B 3/101 for examining the tear film
• CPC Class Codes: G01B 11/0675 using interferometry

Abstract

The invention comprises an apparatus for measuring the relative thickness of the lipid layer component of the precorneal tear film on the surface of an eye after distribution of the lipid layer subsequent to blinking is disclosed. An illuminator directs light to the lipid layer of a patient'"'"'s eye. The illuminator is a broad spectrum light source covering the visible region and is a lambertion light emitter such that the light source is specularly reflected from the lipid layer and undergoes constructive and destructive interference in the lipid layer. A collector collects and focuses the specularly reflected light such that the interference patterns on the tear film lipid layer are observable. The collector also produces an output signal representative of the specularly reflected light which is suitable for further analysis, such as projection on to a high resolution video monitor or analysis by or storage in a computer. In order to facilitate ease of measurement, the patient'"'"'s head may be positioned on an observation platform when the illuminator directs light to the lipid layer of the patient'"'"'s eye.

Claims

1. An apparatus for measuring the thickness of the lipid layer on the surface of a patient'"'"'s eye after distribution of the lipid layer subsequent to blinking comprising:

an illuminator that directs light to the lipid layer of a patient'"'"'s eye, the illuminator comprising a broad spectrum light source in the visible region being a lambertian emitter such that the rays from the light source are specularly reflected from the lipid layer and undergo undergoes constructive and destructive interference in the lipid layer; and

an imaging device for observing the specularly reflected light such that the interference patters on the tear film lipid layer are observable.

2. The apparatus according to claim 1 wherein said illumination means comprises an arcuate emitter and wherein the surface of said lambertian emitter is substantially parallel to the surface of the eye.

3. The apparatus according to claim 1 wherein said means for observing the specularly reflected light comprises a hole defining an opening in the illumination means.

4. The apparatus according to claim 3 wherein said opening in the illumination means allows for observation of the specularly reflected light from behind said illumination means.

5. The apparatus according to claim 3 further including a means for collecting and focusing the specularly reflected light and for generating an output signal representative thereof operatively associated with said opening.

6. The apparatus according to claim 5 further including means for recording the output signal representative of the specularly reflected light.

7. The apparatus according to claim 6 wherein said means for recording the output signal representative of the specularly reflected light records in real time.

8. The apparatus according to claim 5 wherein said means for collecting and focusing the output signal comprises a camera lens system.

9. The apparatus according to claim 6 wherein said means for recording is selected from the group of recording devices consisting of computer memory, video cassette recording devices, analog recording devices and digital recording devices.

10. The apparatus according to claim 1 wherein said specularly reflected light is observed when the patient'"'"'s head is positioned on an observation platform.

11. The apparatus according to claim 2 wherein said arcuate emitter is constructed and arranged such that the light rays emitted therefrom strike the surface of the eye such that Snell'"'"'s Law is satisfied with respect to the acceptance angle of said means for observing the specularly reflected light and produces an observable area of interference on the surface of the eye.

12. The apparatus according to claim 1 wherein said illumination means further includes a plurality of spaced apart light emitting diodes adapted to emit light in the visible region;

and

a diffuser means for diffusing the light emitted by the respective light emitting diodes positioned between said light emitting diodes and the surface of the eye and further, wherein the diffuser means is arcuate such that the light rays emitted therefrom strike the surface of the eye such that Snell'"'"'s law is satisfied with respect to the acceptance angle of said camera lens system so as to produce an observable area of interference on the eye.

13. The apparatus according to claim 11 wherein the light rays that generate the visible viewing area of interference are substantially normal to the surface of the eye.

14. The apparatus according to claim 1 wherein said illumination means has a total radiated power of less than 1 W.

15. An apparatus for measuring the thickness of the lipid layer on the surface of an eye after distribution of the lipid layer subsequent to blinking comprising:

an illuminator that directs light to the lipid layer of a patient'"'"'s eye, the illuminator being a broad spectrum light source in the visible region and being a lambertian emitter such that the light source is specularly reflected from the lipid layer and undergoes constructive and destructive interference in the lipid layer and wherein the total light emitted from the surface of the illumination means is less that 10 μ

W/mm²; and

an imaging device for observing the specularly reflected light such that the interference patterns on the tear film lipid layer are observable.

16. The apparatus according to claim 15 wherein said illumination means further includes an arcuate emitter and wherein the surface of said emitter is substantially parallel to the surface of the eye.

17. The apparatus according to claim 15 wherein said means for observing the specularly reflected light comprises a hole defining an opening in the illumination means.

18. The apparatus according to claim 17 wherein said opening in the illumination means allows for observation of the specularly reflected light from behind said illumination means.

19. The apparatus according to claim 17 further including means for collecting and focusing the specularly reflected light and for generating an output signal representative thereof operatively associated with said opening.

20. The apparatus according to claim 19 further including means for recording the output signal representative of the specularly reflected light.

21. The apparatus according to claim 20 wherein said means for recording the output signal representative of the specularly reflected light records in real time.

22. The apparatus according to claim 19 wherein said means for collecting and focusing comprises a camera lens system.

23. The apparatus according to claim 20 wherein said means for recording is selected from the group of recording devices consisting of computer memory, video cassette recording devices, analog recording devices and digital recording devices.

24. The apparatus according to claim 15 wherein the specularly reflected light is observed when the patient'"'"'s head is positioned on an observation platform.

25. The apparatus according to claim 15 wherein said arcuate emitter is constructed and arranged such that the light rays emitted therefrom strike the surface of the eye such that Snell'"'"'s law is satisfied with respect to the acceptable angle of said means for collecting the specularly reflected light to produce an observable area of interference on the eye.

26. The apparatus according to claim 15 wherein said illumination means further includes a plurality of spaced apart light emitting diodes adapted to emit light in the visible region;

and

a diffuser means for diffusing the light emitted by the respective light emitting diodes positioned between said light emitting diodes and the surface of the eye and further, wherein the diffuser means is arcuate such that the light rays emitted from the lambertian emitter strike the surface of the eye such that Snell'"'"'s law is satisfied with respect to the acceptance angle of said camera lens system to as to produce an observable area of interference on the eye.

27. The apparatus according to claim 25 further including means for collecting the specularly reflected light and for focusing the specularly reflected light generate an output signal representative thereof.

28. The apparatus according to claim 25 wherein said illumination means has a total radiated power of less than 1W.

29. The apparatus according to claim 25 wherein the light rays that generate the visible viewing area of interference are essentially normal to the surface of the eye.

30. An apparatus for measuring the thickness of the lipid layer on the surface of a patient'"'"'s eye after distribution of the lipid layer subsequent to blinking comprising:

an illuminator that directs light to the lipid layer of a patient'"'"'s eye, the illuminator comprising a broad spectrum light source in the visible region and being a uniform illumination lambertian emitter such that the light source is specularly reflected from the lipid layer and undergoes constructive and destructive interference in the lipid layer; and

further wherein the illumination means illuminates the patients face, but wherein only an area below the pupil satisfies Snell'"'"'s law; and

an imagine device for observing the specularly reflected light such that the interference patters on the tear film lipid layer are observable in the area below the pupil with respect to the acceptance angle of the means for observing so as to produce an observable area of interference on the eye below the pupil.

31. The apparatus according to claim 30 further including means for collecting and focusing the specularly reflected light such that the interference patterns on the tear film lipid layer are observable.

32. The apparatus according to claim 30 wherein said illumination means illuminates an area of the patient'"'"'s eye and wherein the area having viewable interference fringes is located below the pupil.

33. The apparatus according to claim 32 wherein the area having viewable interference fringes is an area of at least 12.5 mm².

34. The apparatus according to claim 30 wherein said illumination means has a total illumination intensity of less than that which would induce reflex tearing or cause a proprioceptive response to occur.

35. The apparatus according to claim 34 wherein said illumination means has a total illumination intensity of between about 1 μ

W/mm² and 15 μ

W/mm² at the surface of the illuminator.

36. The apparatus according to claim 32 wherein the specularly reflected light is observed when the patient'"'"'s head is positioned on an observation platform.

37. The apparatus according to claim 30 further including means for recording the observable area of interference of the specularly reflected light.

38. The apparatus according to claim 37 wherein said means for recording the observable area of interference records in real time.

39. The apparatus according to claim 37 wherein said means for recording is selected from the group of recording devices consisting of computer memory, video cassette recording devices, analog recording devices and digital recording devices.

40. The apparatus according to claim 31 wherein said means for collecting and for focusing the specularly reflected light generate an output signal representative thereof.

41. The apparatus according to claim 30 wherein said illumination means comprises an array of light emitting diodes and a diffuser positioned between the respective diode array and the lipid layer of the tear film.

42. The apparatus according to claim 41 where said diffuser is arcuate such that the light rays emitted from the lamertian emitter strike the surface of the eye tangential thereto.

43. An apparatus for measuring the thickness of the lipid layer on the surface of an eye after distribution of the lipid layer subsequent to blinking comprising:

an illuminator that directs light to the lipid layer of a patient'"'"'s eye, the illuminator being a broad spectrum light source in the visible region and being a uniform illumination lambertian emitter such that the light source is specularly reflected from the lipid layer and undergoes constructive and destructive interference in the lipid layer and wherein the light emitted from the illuminator travels directly to the lipid layer without reflection and strikes the lipid layer; and

an imaging device for collecting the specularly reflected light and for focusing the specularly reflected light such that the interference patterns on the tear film lipid layer are observable.

44. The apparatus according to claim 43 further including means for collecting and focusing the specularly reflected light such that the interference patters on the tear film lipid layer are observable.

45. The apparatus according to claim 43 wherein the illumination means illuminates an area of the patient'"'"'s eye and wherein the area having viewable interference fringes is located below the pupil.

46. The apparatus according to claim 43 wherein the area having viewable interference fringes is an area of at least 12.5 mm².

47. The apparatus according to claim 43 wherein the illumination means has a total illumination intensity of less than that which would induce reflect tearing or cause a proprioceptive response to occur.

48. The apparatus according to claim 43 wherein the illumination means has a total illumination intensity of between about 1 μ

W/mm² and 15 μ

W/mm² at the surface of the illuminator.

49. The apparatus according to claim 43 wherein the illumination means has a total radiated power of less than about 1W.

50. The apparatus according to claim 45 wherein the specularly reflected light is observed when the patient'"'"'s head is positioned on an observation platform.

51. The apparatus according to claim 43 further including means for recording the observable area of interference of the specularly reflected light.

52. The apparatus according to claim 51 wherein the means for recording the observable are of interference records in real time.

53. The apparatus according to claim 51 wherein the means for recording is selected from the group of recording devices selected from the group consisting of computer, video cassette recording devices and digital recording devices.

54. The apparatus according to claim 44 wherein the means for collecting and for focusing the specularly reflected light generate an output signal representative thereof.

55. The apparatus according to claim 43 wherein the illumination means comprises an array of light emitting diodes and a diffuser positioned between the respective diode array and the lipid layer of the tear film.

56. The apparatus according to claim 55 where the diffuser is arcuate such that the light rays emitted from the lambertian emitter strike the surface of the eye tangential thereto.