Vascular entoptoscope

• US 5,360,010 A
• Filed: 11/02/1992
• Issued: 11/01/1994
• Est. Priority Date: 05/02/1990
• Status: Expired due to Fees

• Current Assignee: Board of Regents of the University of Texas System (University of Texas System)
• Original Assignee: Board of Regents of the University of Texas System (University of Texas System)
• Inventors: Bradley, Arthur, Applegate, Raymond A.
• Primary Examiner(s): MANUEL, GEORGE C
• Application Number:
  US07/946,321
• Time in Patent Office: 729 Days
• Field of Search: 128/745, 128/691, 128/637, 351/209, 351/210, 351/226, 351/221, 351/246, 356/28, 356/39
• US Class Current: 600/558
• CPC Class Codes: A61B 3/12 for looking at the eye fundus, e.g. ophthalmoscopes A61B3/13 takes precedence
• CPC Class Codes: A61B 3/1241 specially adapted for observation of ocular blood flow, e.g. by fluorescein angiography

Abstract

Described herein are a range of techniques and apparatuses used to study the retinal vasculature near the fovea, a description of the need and rationale for noninvasive in vivo monitoring of the retinal vasculature, a presentation of theoretical and practical considerations which demonstrate that entoptic visualization of the smallest capillaries near the fovea is optimized by a short wavelength source of light which is constrained to enter the eye through a small limiting aperture moving in space near the eye at an optimized velocity in a circular or irregular path, and a discussion of the feasibility of using these techniques in a museum or novelty device as well as a research and clinical tool.

Claims

1. An apparatus for entoptically perceiving the macular area retinal vasculature of a human subject'"'"'s eye under examination, the apparatus comprising:

(a) a light beam source; and

(b) a means of continuously directing a light beam from said source into a subject'"'"'s eye, such that with time the light beam illuminates a same retinal area from constantly varying angles.

2. The apparatus of claim 1 wherein the light beam from said source is variable in intensity and shape.

3. The apparatus of claim 1 wherein the light beam source is a light generator or a light field narrowed through a constraining aperture.

9. The apparatus of claim 1, 4 or 6 wherein a means is provided to correct for refractive error of said eye.

4. An apparatus for entoptically perceiving the macular area retinal vasculature of a human subject'"'"'s eye under examination, the apparatus comprising:

(a) a means of directing a light beam into a subject'"'"'s eye, at angles such that the angle of illumination of said eye'"'"'s retina by the light beam changes with time; and

(b) a means to image an aperture of fixed or variable size and shape at optical infinity or other plane of interest as an optical field stop for said apparatus.

5. The apparatus of claim 4 wherein the light beam is of variable intensity and shape.

6. An apparatus for entoptically perceiving the macular area retinal vasculature of a human subject'"'"'s eye under examination, the apparatus comprising:

(a) a means of directing a light beam into said eye, at angles such that the angle of illumination of said eye'"'"'s retina changes with time;

(b) a means to image an aperture of fixed or variable size and shape at optical infinity or other plane of interest as an optical field stop for said apparatus; and

(c) a luminous or non-luminous fixation point with a means to image said fixation point on the retina of said eye.

7. The apparatus of claim 6 wherein the field stop is sectionalized to facilitate location of vessels or vessel defects with respect to the fixation point.

8. The apparatus of claim 6 wherein a movable luminous or non-luminous point is contained in the optical field stop.

10. An apparatus for entoptically perceiving the macular area retinal vasculature of a human subject'"'"'s eye under examination, the apparatus comprising:

(a) a means of directing a light beam into said eye at angles such that the angle of illumination of said eye'"'"'s retina by the beam changes with time;

(b) a means to image an aperture at optical infinity or other plane of interest as an optical field stop for said apparatus, said aperture being of fixed or variable size and shape; and

(c) a luminous or non-luminous fixation point with a means to image said fixation point on the retina of said eye.

11. The apparatus of claim 10 wherein said light beam is directed in a circular path 2 to 6 mm in diameter.

12. The apparatus of claim 11 wherein said circular path is 3.5 mm in diameter and about centered in said eye'"'"'s pupil.

13. The apparatus of claim 11 wherein said light beam is directed in an irregular path of greatest dimension about 2 to 6 mm such that all angles of retinal illumination obtainable with a circular path are present.

14. An apparatus for entoptically perceiving the macular area retinal vasculature of a human subject'"'"'s eye under examination, the apparatus comprising:

(a) a means of directing said light beam into said eye in a circular path 2 to 6 mm in diameter and about centered in the eye'"'"'s pupil, said beam being retraced at the rate of about 0.5 to 10 Hz, resulting in an area of retinal illumination in which the angle of illumination of said eye'"'"'s retina changes with time;

(b) a means to image an aperture at optical infinity or other plane of interest as an optical field stop for said apparatus, said aperture being of fixed or variable size and shape; and

(c) a luminous or non-luminous fixation point with a means to image said fixation point on the retina of said eye.

15. The apparatus of claim 14 wherein said light beam is directed in an irregular path of greatest dimension about 2 to 6 mm such that all angles of retinal illumination obtainable with a circular path are present.

16. The apparatus of claim 14 wherein said circular path is retraced at the rate of about 3.5 Hz.

17. The apparatus of claim 14 wherein said aperture is that of an adjustable iris diaphragm.

18. The apparatus of claim 14 wherein said eye'"'"'s area of retinal illumination comprises a circle and said fixation point is centered within said circle.

19. An apparatus for entoptically perceiving the macular area retinal vasculature of a human subject'"'"'s eye under examination, the apparatus comprising:

(a) a means of directing a light beam into said eye in a circular path 2 to 6 mm in diameter and about centered in the eye'"'"'s pupil, said beam being retraced at the rate of about 0.5 to 10 Hz, and said light having a peak wavelength of about 430 to 555 nm and a half band pass of 0 to 100 nm, resulting in the angle of illumination of said eye'"'"'s retina changing with time;

(b) a means to image an aperture at optical infinity or other plane of interest as an optical field stop for said apparatus, said aperture being of fixed or variable size and shape; and

(c) a luminous or non-luminous fixation point with a means to image said fixation point on the retina of said eye.

20. The apparatus of claim 19 wherein said light beam is directed in an irregular path of greatest dimension about 2 to 6 mm such that all angles of retinal illumination obtainable with a circular path are present.

21. The apparatus of claim 19 wherein said light beam has a peak wavelength of about 470 nm and a half band pass of ±

about 60 nm.

22. An apparatus for entoptically perceiving the macular area retinal vasculature of a human subject'"'"'s eye under examination, the apparatus comprising:

(a) a means of directing a light beam into said eye through a constraining aperture about 0.1 to 3 mm diameter;

(b) a means of directing a light beam into said eye in a circular path 2 to 6 mm in diameter and about centered in the eye'"'"'s pupil, said beam being retraced at the rate of about 0.5 to 10 Hz, and said light having a peak wavelength of about 430 to 555 nm and a half band pass of 0 to 100 nm, resulting in an angle of illumination of said eye'"'"'s retina changing with time;

(c) a means to image an aperture at optical infinity or other plane of interest as an optical field stop for said apparatus, said aperture being of fixed or variable size and shape; and

(d) a luminous or non-luminous fixation point with a means to image said fixation point on the retina of said eye.

23. The apparatus of claim 22 wherein the constraining aperture is an exit pupil.

24. The apparatus of claim 22 wherein said constraining aperture is of irregular shape with greatest dimension about 0.1 to 3 mm.

25. The apparatus of claim 22 wherein said constraining aperture is of irregular shape with greatest dimension about 1 mm.

26. The apparatus of claim 22 wherein said constraining aperture is imaged between said eye'"'"'s retina and said eye'"'"'s anterior focal plane.

27. The apparatus of claim 22 wherein said light beam enters said eye through a rotating constraining aperture placed in front of said eye.

28. The apparatus of claim 22 wherein said light beam is diffuse and of uniform intensity.

29. An apparatus for entoptically perceiving and mapping the macular area retinal vasculature of a human subject'"'"'s eye under examination, the apparatus comprising:

(a) a means to establish and maintain translational and rotational alignment of said eye with said apparatus;

(b) a light source of variable intensity illuminating an aperture which is imaged in or near the eye'"'"'s entrance pupil plane to form an exit pupil of the apparatus and a means of moving said exit pupil along a path in space;

(c) a means of imaging said exit pupil into said eye'"'"'s entrance pupil at angles such that the angle of illumination of an illuminated area of said eye'"'"'s retina changes with time;

(d) a means to image an aperture stop at optical infinity or other plane of interest to correct for any refractive error as an optical field stop for said apparatus, said aperture being of variable size and shape;

(e) a luminous or nonluminous fixation point and a means to image said fixation point on the retina of said eye;

(f) a luminous or nonluminous tracking point and a means to form an image of the tracking point on the retina of the eye;

(g) a means of moving said tracking point retinal image with respect to said fixation point retinal image;

(h) a means of transducing movement of said tracking point retinal image to yield coordinates of its location on said eye'"'"'s retina with respect to said fixation point retinal image;

(i) a means of compiling or displaying coordinates of said tracking point retinal image movement, said compilation or display comprising a map of tracking point retinal image positions with respect to said fixation point retinal image; and

(j) a means to detect and indicate magnitude and direction of translation of said eye with respect to said apparatus.

30. The apparatus of claim 29 wherein the aperture in step (b) is an entrance pupil of the apparatus.

31. The apparatus of claim 29 wherein the tracking point is a light source.

32. The apparatus of claim 29 wherein the means to establish and maintain rotational alignment is a bite bar for the subject to orally embrace or a chin and forehead rest.

33. The apparatus of claim 29 wherein path of movement of the apparatus exit pupil is circular, about 2 to 6 mm in diameter and about centered in the eye'"'"'s pupil.

34. The apparatus of claim 29 wherein the path of movement of the apparatus exit pupil is circular, 4 mm in diameter and about centered in the eye'"'"'s pupil.

35. The apparatus of claim 29 wherein the path of movement of the apparatus exit pupil is circular, being retraced at the rate of about 0.5 to 10 Hz.

36. The apparatus of claim 29 wherein the path of movement of the apparatus exit pupil is circular, being retraced at the rate of about 3.5 Hz.

37. The apparatus of claim 29 wherein said aperture stop is that of an adjustable iris diaphragm.

38. The apparatus of claim 29 wherein the area of retinal illumination is a circle and said fixation point retinal image is within said circle.

39. The apparatus of claim 29 wherein the area of retinal illumination is a circle and said fixation point retinal image is centered within said circle.

40. The apparatus of claim 29 wherein said light source has a peak wavelength of about 430 to 555 nm and a half band pass of 0 to 100 nm.

41. The apparatus of claim 29 wherein said light source has a peak wavelength of about 470 nm and a half band pass of about ±

60 nm.

42. The apparatus of claim 29 wherein the exit pupil of the apparatus is circular with a diameter of about 0.1 to 3 mm.

43. The apparatus of claim 29 wherein the exit pupil of the apparatus is circular with a diameter of about 1.0 or less.

44. The apparatus of claim 29 wherein the exit pupil of the apparatus is imaged in or near said eye'"'"'s entrance pupil plane.

45. The apparatus of claim 29 wherein the exit pupil of the apparatus is imaged between said eye'"'"'s anterior focal plane and the said eye'"'"'s retina.

46. The apparatus of claim 29 wherein said light source is diffuse and of uniform intensity.

47. The apparatus of claim 29 where said indication of magnitude and direction of translation of said eye with respect to said apparatus in step (j) is visible.

48. The apparatus of claim 29, where said indication of magnitude and direction of translation of said eye with respect to said apparatus in step (j) is sensed by an external operator.

49. The apparatus of claim 29 where said indication of magnitude and direction of translation of said eye with respect to said apparatus in step (j) is detected by a sensor and monitored by a computer.

50. The apparatus of claim 29 wherein tracking point retinal image coordinates of step (h) are corrected manually for retinal image translation caused by any translation of said eye with respect to said apparatus.

51. The apparatus of claim 29 wherein tracking point retinal image coordinates of step (h) are corrected by automatic computation for retinal image translation caused by translation of said eye with respect to said apparatus.

52. The apparatus of claim 29 wherein tracking point retinal image coordinates in step (i) are calibrated in units of length measured on said retinal surface.

53. The apparatus of claim 29 wherein tracking point retinal image coordinates in step (i) are calibrated in units of angular subtense.

54. The apparatus of claim 29 wherein said means of moving said tracking point retinal image of step (h) is a joystick or similar x-y controller.

55. An apparatus for entoptically perceiving and mapping white blood cell circulation and macular retinal vasculature of a human subject'"'"'s eye under examination, the apparatus comprising:

(a) a means to establish and maintain translational alignment of a subject'"'"'s eye with the apparatus;

(b) a light source of variable intensity illuminating an aperture which is imaged in or near the eye'"'"'s entrance pupil plane to form an exit pupil of the apparatus, and a means of moving said exit pupil along a path in space;

(c) a means of imaging said device apparatus exit pupil into said eye'"'"'s entrance pupil at angles such that the angle of retinal illumination of said eye'"'"'s retina changes with time;

(d) a means to image an aperture stop at optical infinity or other plane of interest to correct for refractive error as an optical field stop for said apparatus, said aperture being of variable size and shape;

(e) a luminous or nonluminous fixation point and a means to image said fixation point on the retina of said eye;

(f) a luminous or nonluminous tracking point and a means to form an image of the tracking point on the retina of the eye;

(g) a means of moving said tracking point retinal image with respect to said fixation point retinal image;

(h) a means of transducing movement of said tracking point retinal image to yield coordinates of its location on said eye'"'"'s retina with respect to said fixation point retinal image;

(i) a means of compiling or displaying said coordinates of said tracking point retinal image movement, said compilation or display comprising a map of said tracking point retinal image positions with respect to said fixation point retinal image;

(j) a means to detect and indicate magnitude and direction of translation of said eye with respect to said apparatus;

(k) a blue-field light source of variable intensity and a means to illuminate said eye'"'"'s retina with said blue-field light source;

(l) a luminous or nonluminous speed-comparator and a means to form a retinal image of said speed-comparator on said eye'"'"'s retina, said speed-comparator retinal image being of a size about equal to said entoptically perceived white blood cells;

(m) a means of causing said speed-comparator retinal image to move along a fixed or variable path on said eye'"'"'s retina at a fixed or variable velocity; and

(n) a means of rotating and translating said speed comparator retinal image on said eye'"'"'s retina.

56. The apparatus of claim 55 wherein the exit pupil of the apparatus has a circular path of movement about 2 to 6 mm in diameter and about centered in the eye'"'"'s pupil.

57. The apparatus of claim 55 wherein the exit pupil of the apparatus has a circular path of movement 4 mm in diameter and about centered in the eye'"'"'s pupil.

58. The apparatus of claim 55 wherein the exit pupil of the apparatus has a circular path of movement which is retraced at the rate of about 0.5 to 10 Hz.

59. The apparatus of claim 55 wherein the exit pupil of the apparatus has a circular path of movement which is retraced at the rate of about 3.5 Hz.

60. The apparatus of claim 55 wherein said aperture stop is that of an adjustable iris diaphragm.

61. The apparatus of claim 55 wherein said eye'"'"'s area of retinal illumination is a circle and said fixation point retinal image is within said circle.

62. The apparatus of claim 55 wherein said eye'"'"'s area of retinal illumination comprises a circle and said fixation point retinal image is centered within said circle.

63. The apparatus of claim 55 wherein said light source has a peak wavelength of about 430 nm and 555 nm and a half band pass of 0 to 100 nm.

64. The apparatus of claim 55 wherein said light source has a peak wavelength of about 470 nm and a half band pass of about ±

60 nm.

65. The apparatus of claim 55 wherein the exit pupil of the apparatus is circular with a diameter of about 0.1 to 3 mm.

66. The apparatus of claim 55 wherein the exit pupil of the apparatus is circular with a diameter of about 1.0 mm or less.

67. The apparatus of claim 55 wherein the exit pupil of the apparatus is imaged in or near said eye'"'"'s entrance pupil plane.

68. The apparatus of claim 55 wherein the exit pupil of the apparatus is imaged between said eye'"'"'s anterior focal plane and said eye'"'"'s retina.

69. The apparatus of claim 55 wherein said light source is diffuse and of uniform intensity.

70. The apparatus of claim 55 where said indication of magnitude and direction of translation of said eye with respect to said apparatus in step (j) is visible.

71. The apparatus of claim 55 where said indication of magnitude and direction of translation of said eye with respect to said apparatus in step (j) is sensed by an external operator.

72. The apparatus of claim 55 where said indication of magnitude and direction of translation of said eye with respect to said apparatus in step (j) is detected by a sensor and monitored by a computer.

73. The apparatus of claim 55 wherein said tracking point retinal image coordinates of step (h) are corrected manually for retinal image translation caused by translation of said eye with respect to said apparatus.

74. The apparatus of claim 55 wherein said tracking point retinal image coordinates of step (h) are corrected by automatic computation for retinal image translation caused by translation of said eye with respect to said apparatus.

75. The apparatus of claim 55 wherein said tracking point retinal image coordinates in step (i) are calibrated in units of length measured on said retinal surface.

76. The apparatus of claim 55 wherein said tracking point retinal image coordinates in step (i) are calibrated in units of angular subtense.

77. The apparatus of claim 55 wherein said means of moving said tracking point retinal image of step (h) is a joystick or similar x-y controller.

78. The apparatus of claim 55 wherein said blue-field light source has a dominant wavelength of about 430 to 500 nm.

79. The apparatus of claim 55 wherein light from said blue-field light source is directed coaxially with the instrument'"'"'s optical axis.

80. The apparatus of claim 55 wherein said blue-field light source is about 50% of total light.

81. The apparatus of claim 55 wherein said blue-field light is applied to said retina constantly or intermittently in alternation with the light source of step (a) at a rate which minimizes perceptual flicker and having a duty cycle variable to optimize perception of both retinal vessels and white blood cells.

82. The apparatus of claim 55 wherein said retinal path of said speed-comparator light image is curved to mimic the course of a retinal vessel.

83. The apparatus of claim 55 wherein said retinal path of said speed-comparator light image is straight.

84. The apparatus of claim 55 wherein said retinal path of said speed-comparator retinal image is about 10^-4 to 10^-3 m in length.

85. The apparatus of claim 55 wherein said velocity of the speed comparator can be adjusted to mimic velocity of a white corpuscle passing through vasculature.