Ophthalmic device to diagnose the eye fundus

• US 4,402,325 A
• Filed: 09/12/1980
• Issued: 09/06/1983
• Est. Priority Date: 09/29/1979
• Status: Expired due to Term

• Current Assignee: Minolta Camera Kabushiki Kaisha
• Original Assignee: Minolta Camera Kabushiki Kaisha
• Inventors: Sawa, Seija
• Primary Examiner(s): Howell, Kyle L.
• Assistant Examiner(s): Hindenburg, Max F.
• Application Number:
  US06/186,669
• Time in Patent Office: 1,089 Days
• Field of Search: 128/664-666, 128/691, 128/745, 128/637, 128/645, 128/649-650, 128/652, 128/297, 128/6, 128/676, 351/6-7, 354/62-63
• US Class Current: 600/479
• CPC Class Codes: A61B 3/1241 specially adapted for observation of ocular blood flow, e.g. by fluorescein angiography
• CPC Class Codes: A61B 3/125 with contact lenses contact lenses per se G02C7/04
• CPC Class Codes: A61B 5/02216 Ophthalmodynamometers

Abstract

The present invention provides an ophthalmic device to diagnose the circulation of blood in an eye fundus by producing a pair of plethysmograms for synchronized comparison. A pair of fiber optic conduits are attached to a coupler that can be sealingly affixed to the exterior surface of the cornea of an eye. The coupler can be attached to the exterior surface of the eye by the application of subatmospheric pressure within the coupler. Light is introduced on the axis of the pupil through a central light exit region that is physically small enough relative to a dilated pupil to prevent the reflection of light from the iris. The light reflected from the eye fundus is received in a peripheral light receiving region. The light signals are converted into electrical voltage levels that are ultimately used to produce a visual display of the plethysmograms.

Claims

1. An opthalmic device for measuring blood circulation in the eye fundus to diagnose the condition of the eye comprising:

means for generating a source light including wavelengths in at least the visible and near infrared range;

means for introducing the source light into an eye;

means for receiving the light reflected from the fundus of the eye;

first means responsive to a visible wavelength band of light picked up by the receiving means for producing a first electric signal indicative of a first plethysmogram;

second means responsive to a near infrared wavelength band of light picked up by the receiving means for producing a second electric signal indicative of a second plethysmogram; and

means responsive to the first and second electric signals for visually presenting waveforms of the individual first and second plethysmograms to provide a synchronized comparison therebetween, whereby diagnosis of the eye is possible as a result of the synchronized comparison between the visually and individually presented waveforms of the first and second plethysmograms.

2. The invention of claim 1, further comprising means for transmitting the visible wavelength band of light picked up by the receiving means to the first producing means and for transmitting the near infrared wavelength band of light picked up by the receiving means to the second producing means.

3. The invention of claim 2, wherein the visible wavelength band is defined between 550 to 600 mμ

while the near infrared wavelength band is defined between 700 to 1000 mμ

by the transmitting means.

4. The invention of claim 1 wherein the means for presenting the waveforms comprises means connected to the first and second producing means for synchronously and individually recording on paper the first and second plethysmograms.

5. The invention of claim 1 wherein the means for presenting the waveforms comprises means connected to the first and second mens for synchronously and individually displaying the first and second plethysmograms.

6. The invention of claim 1, wherein the introducing means comprises a light exit, and the receiving means comprises a light entrance concentrically arranged around the light exit, the radius of the periphery of the light entrance is less than the normal radius of the pupil of an eye dilated by a mydriatic.

7. The invention of claim 6, further comprising means for adhering the light exit and light entrance to the front of the eye and means for flexibly supporting the light exit and light entrance to allow free motion thereof to follow movement of the eyeball.

8. The invention of claim 7, wherein the adhering means comprises a tube arranged around the light entrance with a gap formed therebetween and means for removing the air in a space enclosed by the eye front, the tube and the light entrance.

9. An opthalmic device for a novel diagnosis method by means of measuring the blood circulation in the eye fundus comprising:

first means for photoelectrically obtaining a first plethysmogram from an eye fundus with respect to visible light in the wavelength band of 550 to 650 mμ

;

second means for photoelectrically obtaining a second plethysmogram from the eye fundus with respect to near infrared light in the wavelength band of 700 to 1000 mμ

; and

means for realizing a synchronized comparison of the relative phase and amplitude of the first and second plethysmograms, whereby diagnosis is possible as a result of the comparison.

10. An opthalmic device for measuring blood circulation in the eye fundus to diagnose the condition of the eye and patient comprising:

a source light for generating wavelengths in at least the bandwidth of 550 to 1000 mμ

;

an optical system for directing the source light into the eye, and receiving the light reflected from the fundus of the eye;

a first light sensing device connected to the optical system for providing a first continuous plethysmogram signal of reflected light representative of a wavelength band within the range of 550 to 700 mμ

;

a second light sensing device connected to the optical system for providing a second continuous plethysmogram signal of reflected light representative of the wavelength band within the range of 700 to 1000 mμ

; and

means for synchronizing the first and second continuous plethysmogram signals to permit a comparison of the phase and amplitude of the respective plethysmograms whereby their relative values can be compared with predetermined known values to diagnose the condition of the eye and patient.

11. The invention of claim 10 wherein the optical system includes a light exit member capable of being located adjacent an optical axis of an eye surface for projecting the source light into and through a dilated eye pupil without reflection from the iris and a light entrance member capable of being located adjacent and off the optical axis of the eye for receiving the light reflected from the fundus of the eye.

12. The invention of claim 11 further including means for flexibly supporting the optical system adjacent and in contact with the eye to allow substantially free movement of the optical system to track the minute motion of the patients'"'"' eye and thereby substantially eliminate the introduction of signal noise from eye movements in the resulting plethysmograms.

13. The invention of claim 12 further including means for adhering the optical system to the eye surface.

14. A noninvasive opthalmic apparatus for facilitating measurement of an eye comprising:

means for measuring a property of an eye including a light source, a first light guide for directing light into the eye having a light exit region located adjacent the cornea of the eye and aligned with an axis of the pupil transverse to and extending approximately through the center of the pupil of the eye, a second light guide for receiving light reflected from the eye having a light entrance region offset from the axis of the pupil and means for monitoring the reflected light;

means for providing a sealing contact to the exterior surface of the eye to facilitate positioning of the light exit and entrance regions relative to the eye;

means for providing a subatmospheric pressure to the surface of the eye to maintain an operative position of the light exit and entrance regions and the eye; and

means for flexibly supporting the light exit and entrance regions to permit free movement thereof to substantially follow any physical motion of the eye.

15. The invention of claim 14 wherein the light entrance region is concentrically arranged about the light exit region, the radius of the periphery of the light entrance is less than the radius of a conventional dilated pupil subject to measurement.

16. An opthalmic device for measuring the blood circulation in the eye fundus to diagnose the condition of the eye, comprising:

17. means for generating a source light;

a light exit capable of location adjacent an eye surface for projecting the source light from the generating means into the eye;

a light entrance capable of location adjacent an eye surface for picking up the light reflected from the fundus of the eye;

means responsive to the light picked up by the light entrance for producing an electric signal indicative of information relating to the blood circulation in the eye fundus, wherein the light entrance is concentrically arranged around the light exit, the radius of the periphery of the light entrance is less than the radius of a normal eye pupil dilated by a mydriatic; and

means for adhering the light exit and light entrance to the eye surface.