Fundus blood flow metering method

• US 6,302,850 B1
• Filed: 09/08/1999
• Issued: 10/16/2001
• Est. Priority Date: 09/10/1998
• Status: Active Grant

• Current Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Original Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Inventors: Tsukada, Mamoru
• Primary Examiner(s): WINAKUR, ERIC FRANK
• Application Number:
  US09/392,304
• Time in Patent Office: 769 Days
• Field of Search: 600/504, 600/407, 600/318, 600/479, 600/480, 351/206, 351/208, 351/211, 351/215, 351/216, 356/27, 356/28, 356/39-47
• US Class Current: 600/504
• CPC Class Codes: A61B 3/1233 for measuring blood flow, e.g. at the retina

Abstract

A fundus blood flow metering method includes a series of steps of carrying out alignment of the positional relation with an eye to be examined, carrying out aiming of a blood vessel to be measured, and measuring a velocity of blood flow while tracking the blood vessel so as to track and capture eye movement. After the sequential operation, the direction of incidence of a measuring beam is switched to another direction and the series of steps are again carried out for the same blood vessel, starting from the alignment.

Claims

1. A method for measuring the blood flow of a fundus blood vessel on an eye to be examined, by irradiating the blood vessel with a light beam, detecting scattered and reflected light from the irradiated vessel, and calculating the velocity of the blood flow based on the detection, said method comprising the steps of:

executing a first measurement of the blood flow while irradiating the blood vessel with a light beam from a first direction;

carrying out alignment related to the eye after executing the first measurement in said first measurement executing step;

allowing an operator to confirm the alignment state and awaiting the operator'"'"'s order; and

executing a second measurement of the blood flow, based on the operator'"'"'s order, while irradiating the blood vessel with a light beam from a second direction different from the first direction.

2. The method according to claim 1, further comprising the step of automatically adjusting a gain of the detection during the first and second measurements.

3. The method according to claim 1, wherein said alignment related to the eye comprises focus adjustment.

4. The method according to claim 1, wherein said alignment related to the eye comprises tracking adjustment.

5. The method according to claim 1, wherein said detection is executed by detecting the scattered and reflected light with a plurality of detectors arranged at different angles.

6. An apparatus for measuring a fundus blood vessel on an eye to be examined comprising:

an irradiation system having a light source, for irradiating the blood vessel with a light beam;

a detection system having detectors for detecting scattered and reflected light from the irradiated vessel;

an operation device allowing an operator to order measurement; and

a controller configured to;

execute a first measurement of the blood flow while controlling said irradiation system to irradiate the blood vessel with a light beam from a first direction;

carry out alignment related to the eye after the first measurement;

await an operator'"'"'s order with said operation device; and

execute a second measurement of the blood flow, based on the operator'"'"'s order with said operation device, while controlling said irradiation system to irradiate the blood vessel with a light beam from a second direction different from the first direction.

7. The apparatus according to claim 6, further comprising an automatic gain controller configured to automatically adjust the gain of the detectors during the first and second measurements.

8. The apparatus according to claim 6, further comprising a focus adjustment system for performing a focus operation to carry out the alignment controlled by said controller.

9. The apparatus according to claim 6, further comprising a tracking system configured to perform a tracking operation.

10. The apparatus according to claim 9, wherein said tracking system comprises an image intensifier and an automatic gain controller for the image intensifier.

11. The apparatus according to claim 6, wherein the first measurement is commenced based on the operator'"'"'s order with said operation device.