Vascular entoptoscope

• US 5,016,643 A
• Filed: 05/02/1990
• Issued: 05/21/1991
• Est. Priority Date: 05/02/1990
• Status: Expired due to Term

• 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): Jaworski, Francis
• Assistant Examiner(s): MANUEL, GEORGE C
• Application Number:
  US07/518,065
• Time in Patent Office: 384 Days
• Field of Search: 128/637, 128/691, 128/745, 356/28, 356/39, 351/209, 351/210, 351/221, 351/246
• 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 an apparatus and range of techniques 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 small short wavelength source (1 mm or less) rotating at 3.5 Hz in a circular path (radius 2 mm) imaged in the plane of the eye'"'"'s entrance pupil and a discussion of the feasibility of using these techniques as a rese

Research relating to the development of the present invention was supported in part by grants from the United States Department of Health and Human Services (NIH EY08005 and EY07638). The United States government may have corresponding rights to the license and use of any resulting patent.

Claims

1. An apparatus for entoptically perceiving and mapping the foveal area vasculature of the retina 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 main light source which is imaged in or near the eye'"'"'s entrance pupil plane and a means of moving said main light source or said image along a path in space, said main light source being of variable intensity and shape;

(c) a means of directing said main light image into said eye'"'"'s entrance pupil, resulting in an angle of illumination of said eye'"'"'s retina changing with time;

(d) a means to image an aperture 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 fixation light source and a means to form a fixation light image on the retina of said eye, said fixation light source being of variable intensity;

(f) a tracking light source and a means to form an image of tracking light from said source on the retina of the eye, said tracking light source being of variable intensity;

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

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

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

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

2. The apparatus of claim 1 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.

3. The apparatus of claim 1 wherein said main light image path is circular, about 2 to 6 mm in diameter and about centered in the eye'"'"'s pupil.

4. The apparatus of claim 1 wherein said main light image path is circular, 4 mm in diameter and about centered in the eye'"'"'s pupil.

5. The apparatus of claim 1 wherein said main light path is circular, being retraced at the rate of about 0.5 to 10 Hz.

6. The apparatus of claim 1 wherein said main light path is circular, being retraced at the rate of about 3.5 Hz.

7. The apparatus of claim 1 wherein said aperture is that of an adjustable iris diaphragm.

8. The apparatus of claim 1 wherein said eye'"'"'s area of retinal illumination comprises a circle and said fixation light retinal image is within said circle.

9. The apparatus of claim 1 wherein said eye'"'"'s area of retinal illumination comprises a circle and said fixation light retinal image is centered within said circle.

10. The apparatus of claim 1 wherein said main light source has a peak wavelength of about 430 to 555 nm and a half band pass of about +/- 60 nm.

11. The apparatus of claim 1 wherein said main light source has a peak wavelength of about 470 nm and a half band pass of +/- about 60 nm.

12. The apparatus of claim 1 wherein said main light source image is circular with a diameter of about 0.5 to 3 mm.

13. The apparatus of claim 1 wherein said main light source image is circular with a diameter of about 1.0 mm or less.

14. The apparatus of claim 1 wherein said main light source is imaged in or near said eye'"'"'s entrance pupil plane.

15. The apparatus of claim 1 wherein said main light source is imaged in or near said eye'"'"'s anterior focal plane.

16. The apparatus of claim 1 wherein said main light source image is diffuse and of uniform intensity.

17. The apparatus of claim 1, where in step (j) said indication of magnitude and direction of translation of said eye with respect to said apparatus is visible.

18. The apparatus of claim 1, where in step (j) said indication of magnitude and direction of translation of said eye with respect to said apparatus is sensed by an external operator.

19. The apparatus of claim 1 where in step (j) said indication of magnitude and direction of translation of said eye with respect to said apparatus is sensed by a sensor and monitored by a computer.

20. The apparatus of claim 1 wherein said tracking light retinal image coordinates of steps (h) and (i) are corrected manually for retinal image translation caused by any translation of said eye with respect to said apparatus.

21. The apparatus of claim 1 wherein said tracking light retinal image coordinates of steps (h) and (i) are corrected by automatic computation for retinal image translation caused by translation of said eye with respect to said apparatus.

22. The apparatus of claim 1 wherein said tracking light retinal image coordinates in step (i) are calibrated in units of length measured on said retinal surface.

23. The apparatus of claim 1 wherein said tracking light retinal image coordinates in step (i) are calibrated in units of angular subtense.

24. The apparatus of claim 1 wherein said means of moving said tracking light retinal image is a joy stick or similar x-y manual controller.

25. A method for entoptically perceiving and mapping the foveal area vasculature in the retina of the eye of a human subject under examination with respect to the retinal point of fixation of said eye, the method comprising:

(a) optically directing a main light source image within said eye'"'"'s entrance pupil to illuminate a portion of said eye'"'"'s retina defined by a field stop, said image being of variable intensity;

(b) causing said main light source image to move along a main light path in space, said main light path in space resulting in said eye'"'"'s angle of retinal illumination changing with time;

(c) optically directing a fixation light source on said eye'"'"'s retina and forming thereon a fixation light retinal image, said fixation light source image being of variable intensity;

(d) having said subject visually fixate on said fixation light source image;

(e) having said subject report descriptions of entoptically perceived vascular features of interest near the foveal area of said eye;

(f) optically directing a tracking light source on said eye'"'"'s retina and forming thereon a tracking light retinal image, said tracking light source image being variable in intensity and movable over said eye'"'"'s retinal surface with respect to said fixation retinal image through a tracking light controller operated by said subject;

(g) causing said fixation light, and tracking light source images to be viewed by said eye through an optical field stop aperture illuminated by the main light, said aperture being imaged at infinity or other plane of interest;

(h) scaling outputs of said tracking light controller to correspond to distances and angles measured on said eye'"'"'s retinal surface;

(i) having said subject move said tracking light retinal image along or around said entoptically perceived vascular features of interest while said subject maintains constant translational and rotational alignment of said eye with said fixation light retinal image;

(j) using said scaled outputs of said tracking light controller to create position reports of said entoptically perceived vascular features of interest on said eye'"'"'s retina;

(k) combining said position reports with said descriptions of said entoptically perceived vascular features of interest to create a retinal vascular map;

(1) having said subject adjust said intensities of said main, fixation and tracking light sources for best entoptic visualization;

(m) having said subject adjust complete rotation frequency and thus velocity of the main light source image;

(n) observing said eye to detect misalignment with said fixation light retinal image due to any combination of translation or rotation of said eye;

(o) determining corrections required to said position reports resulting from said misalignment of said eye with respect to said fixation light retinal image; and

(p) applying said corrections to said position reports.

26. The method of claim 25 wherein said main light path in space is circular.

27. The method of claim 25 wherein said main light path in image space is circular, 2 to 6 mm in diameter, and about centered in the eye'"'"'s pupil.

28. The method of claim 25 wherein said main light path in image space is about 4 mm in diameter and about centered in the eye'"'"'s pupil.

29. The method of claim 25 wherein said main light path in space is circular, being retraced at the rate of about 0.5 to 10 Hz.

30. The method of claim 25 wherein said main light path in space is circular, being retraced at the rate of about 3.5 Hz.

31. The method of claim 25 wherein said field stop aperture is an adjustable iris diaphragm.

32. The method of claim 25 wherein said eye'"'"'s area of retinal illumination comprises a circle and said fixation light retinal image is within said circle.

33. The method of claim 25 wherein said eye'"'"'s area of retinal illumination comprises a circle and said fixation light retinal image is centered within said circle.

34. The method of claim 25 wherein said main light source image has a peak wavelength of about 430 to 555 nm and a half band pass of about +/- 60 nm.

35. The method of claim 25 wherein said main light source image has a peak wavelength of about 470 nm and a half band pass of about 60 nm.

36. The method of claim 25 wherein said main light source image is circular with a diameter of about 0.5 to 3 mm.

37. The method of claim 25 wherein said main light source image is circular with a diameter of about 1.0 mm or less.

38. The method of claim 25 wherein said main light source image is focused in or near said eye'"'"'s entrance pupil plane.

39. The method of claim 25 wherein said main light source image is focused in or near said eye'"'"'s anterior focal plane.

40. The method of claim 25 wherein said main light source image is diffuse and of uniform intensity.

41. The method of claim 25 wherein said corrections in step (o) of said position reports are determined by a human operator.

42. The method of claim 25 wherein said corrections in step (o) of said position reports are determined by an automatic computer.

43. An apparatus for entoptically perceiving and mapping the white blood cell circulation and foveal area vasculature in the retina of a the human subject'"'"'s eye under examination, the apparatus comprising:

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

(b) a main light source which is imaged in or near the eye'"'"'s entrance pupil, and a means of moving said main light source or its image along a main light path in space, said main light source being of variable intensity;

(c) a means of optically directing said main light image into said eye'"'"'s entrance pupil, resulting in said eye'"'"'s angle of retinal illumination changing with time;

(d) a means to image an aperture 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;

(e) a fixation light source and a means to form a fixation light image on the retina of said eye, said fixation light source being of variable intensity;

(f) a tracking light source and a means to form a tracking light image on the retina of said eye, said tracking light source being of variable intensity;

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

(h) a means of transducing movement of said tracking light retinal image with respect to said fixation light retinal image to yield coordinates of its location on said retina with respect to location of said fixation light retinal image;

(i) a means of compiling or displaying said coordinates of tracking light image movement, said compilation or display comprising a map of said tracking light retinal image locations with respect to location of said fixation light 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 and a means to illuminate said eye'"'"'s retina with said blue-field light source, said blue-field light source being of variable intensity;

(l) a speed-comparator light source casting an image and a means to form a retinal image of said speed-comparator light on said eye'"'"'s retina, said speed-comparator light source being of variable intensity and said speed-comparator light source 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 path on said eye'"'"'s retina at a fixed velocity, said path and velocity being variable; and

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

44. The apparatus of claim 43 wherein said main light path image space is circular, about 2 to 6 mm in diameter and about centered in the eye'"'"'s pupil.

45. The apparatus of claim 43 wherein said main light path image space is circular, 4 mm in diameter and about centered in the eye'"'"'s pupil.

46. The apparatus of claim 43 wherein said main light path is circular, being retraced at the rate of about 0.5 to 10 Hz.

47. The apparatus of claim 43 wherein said main light path is circular, being retraced at the rate of 3.5 Hz.

48. The apparatus of claim 43 wherein said aperture is that of an adjustable iris diaphragm.

49. The apparatus of claim 43 wherein said area of retinal illumination comprise a circle and said fixation light retinal image is within said circle.

50. The apparatus of claim 43 wherein said area of retinal illumination comprises a circle and said fixation light retinal image is centered within said circle.

51. The apparatus of claim 43 wherein said main light source has a peak wavelength of between about 430 nm and 555 nm and a half band pass of about +/- 60 nm.

52. The apparatus of claim 43 wherein said main light source has a peak wavelength of about 470 nm and a half band pass of about +/- 60 nm.

53. The apparatus of claim 43 wherein said main light source image is circular with a diameter of about 0.5 to 3 mm.

54. The apparatus of claim 43 wherein said main light source image is circular with a diameter of about 1.0 mm or less.

55. The apparatus of claim 43 wherein said main light source is imaged in or near said eye'"'"'s entrance pupil plane.

56. The apparatus of claim 43 wherein said main light source is imaged in or near said eye'"'"'s anterior focal plane.

57. The apparatus of claim 43 wherein said main light source image is diffuse and of uniform intensity.

58. The apparatus of claim 43 where in step (j) said indication of magnitude and direction of translation of said eye with respect to said apparatus is visible.

59. The apparatus of claim 43 where in step (j) said indication of magnitude and direction of translation of said eye with respect to said apparatus is sensed by an external operator.

60. The apparatus of claim 43 where in step (j) said indication of magnitude and direction of translation of said eye with respect to said apparatus is sensed by an external computer.

61. The apparatus of claim 43 wherein said tracking light retinal image coordinates of step (h) are corrected manually for retina image translation caused by translation of said eye with respect to said apparatus.

62. The apparatus of claim 43 wherein said tracking light 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.

63. The apparatus of claim 43 wherein said tracking light retinal image coordinates of step (h) are calibrated in units of length measured on said retinal surface.

64. The apparatus of claim 43 wherein said tracking light retinal image coordinates of step (h) are calibrated in units of angular subtense.

65. The apparatus of claim 43 wherein said means of moving said tracking light retinal image of step (h) is a joy stick or similar x-y manual controller.

66. The apparatus of claim 43 wherein said blue-field light source has a dominant wavelength of about 430 to 500 nm.

67. The apparatus of claim 43 wherein light from said blue-field light source is directed coaxially with the instrument'"'"'s optical axis.

68. The apparatus of claim 43 wherein said blue-field light source comprises about 50% of total light.

69. The apparatus of claim 43 wherein said blue-field light is applied to said retina constantly or intermittently in alternation with the eccentric moving light source at a rate of 40 to 70 Hz, the duty angle being variable to optimize perception of both the retinal vessels and the white blood cells.

70. The apparatus of claim 43 wherein said retinal path of said speed-comparator light image is curved to mimic the course of a retinal vessel.

71. The apparatus of claim 43 wherein said retinal path of said speed-comparator light image is straight.

72. The apparatus of claim 43 wherein said retinal path of said speed-comparator light image is about 10^-3 to 10^-2 m in length.

73. The apparatus of claim 43 wherein said velocity of the speed comparator can be adjusted to mimic velocity of a white corpuscle passing through vasculature.

74. A method for entoptically perceiving and mapping the white blood cell circulation and foveal area vasculature in the retina of the eye of a human subject under examination with respect to the retinal point of fixation of said eye, the method comprising:

(a) optically directing an image of a main light source within or near said eye'"'"'s entrance pupil so as to illuminate a portion of said eye'"'"'s retina defined by a field stop, said main light source image being of variable intensity;

(b) causing said main light image to move along a main light path in space, said path resulting in said eye'"'"'s retinal illumination angle changing with time;

(c) optically directing a fixation light source on said retina, resulting in the formation of a fixation light retinal image, said fixation light source being of variable intensity;

(d) having said subject visually fixate on said fixation light retinal image;

(e) having said subject provide descriptions of entoptically perceived vascular features of interest near said eye'"'"'s foveal area;

(f) optically directing a tracking light source on said eye'"'"'s retina, resulting in the formation of a tracking light retinal image, said tracking light retinal image being movable over said retinal surface with respect to said fixation light retinal image through a tracking light image controller operated by said subject;

(g) computing scaled outputs of said tracking light image controller to correspond to distances and angles measured on said retinal surface;

(h) having said subject move said tracking light retinal image along or around said entoptically perceived vascular features of interest while said subject maintains constant translational and rotational alignment of said eye with said fixation light retinal image;

(i) using said scaled outputs of said tracking light retinal image controller to create position reports of said entoptically perceived vascular features of interest on said retina;

(j) combining said position reports with said descriptions of said subject'"'"'s entoptically perceived vascular features of interest to create a retinal map;

(k) observing said eye to detect misalignment with the instrumentation or said fixation light retinal image due to any combination of translation or rotation of said eye with respect to said fixation light retinal image;

(1) determining corrections required to said position reports resulting from said misalignment of said eye;

(m) applying said corrections to said position reports;

(n) illuminating said eye'"'"'s retina in alternation with said main light source or constantly with a blue-field light source, said blue-field light source being of variable intensity and, if alternating, having a duty cycle of less than 100%;

(o) having said subject report entoptic perception of said white blood cell circulation;

(p) causing said fixation light and tracking light images to be viewed by said eye through an optical field stop aperture, said aperture being imaged at infinity or other plane of interest; and

(q) having said subject adjust one or both of intensity and duty cycle of said light sources for best entoptic perception;

75. The method of claim 74 wherein said main light path in space is circular.

76. The method of claim 74 wherein said main light path in image space is circular, about 2 to 6 mm in diameter, and about centered in the eye'"'"'s pupil.

77. The method of claim 74 wherein said main light path in image space is circular and 4 mm in diameter and about centered in the eye'"'"'s pupil.

78. The method of claim 74 wherein said main light path in space is circular, being retraced at the rate of about 0.5 to 10 Hz.

79. The method of claim 74 wherein said main light path in space is circular, being retraced at the rate of about 3.5 Hz.

80. The method of claim 74 wherein said aperture stop of step (p) is that of an adjustable iris diaphragm.

81. The method of claim 74 wherein said illuminated portions of said eye'"'"'s retina by said main light source in step (a) comprise a circle and said fixation light retinal image is within said circle.

82. The method of claim 74 wherein illuminated portions of said eye'"'"'s retina by said main light source comprise a circle and said fixation light retinal image is centered within said circle.

83. The method of claim 74 wherein said main light source has a peak wavelength of between 430 nm and 555 nm and a half band pass of about +/- 60 nm.

84. The method of claim 74 wherein said main light source has a peak wavelength of about 470 nm and a half band pass of about +/- 60 nm.

85. The method of claim 74 wherein said main light source image is circular with a diameter of 0.5 to 3 mm.

86. The method of claim 74 wherein said main light source image is circular with a diameter of about 1.0 mm or less.

87. The method of claim 74 wherein said main light source image is focused in or near said eye'"'"'s entrance pupil plane.

88. The method of claim 74 wherein said main light source image is focused in or near said eye'"'"'s anterior focal plane.

89. The method of claim 74 wherein said main light source image is diffuse and of uniform intensity.

90. The method of claim 74 wherein said determining of corrections of said position reports is made by a human operator.

91. The method of claim 74 wherein said determining of corrections of said position reports is made by an automatic computer.

92. The method of claim 74 wherein application of said corrections to position reports is made by a human operator.

93. The method of claim 74 wherein application of said corrections to position reports is made by an automatic computer.