APPARATUS AND METHOD FOR OBJECTIVE PERIMETRY VISUAL FIELD TEST

• US 20100149488A1
• Filed: 03/07/2008
• Published: 06/17/2010
• Est. Priority Date: 03/08/2007
• Status: Active Grant

• Current Assignee: Liang Chen, Patrick Lo
• Original Assignee: Liang Chen, Patrick Lo
• Inventors: Chen, Liang, To, Chi Ho, Lo, Patrick
• Granted Patent: US 8,500,278 B2
• Time in Patent Office: Days
• US Class Current: 351/206
• CPC Class Codes: A61B 3/024 for determining the visual field, e.g. perimeter types
• CPC Class Codes: A61B 3/113 for determining or recording eye movement
• CPC Class Codes: G06V 40/19 Sensors therefor

Abstract

Apparatus for testing a subject'"'"'s visual field includes a data processor, which can be provided by a general purpose computer, coupled to a pupil tracking system. The data processor is programmed to cause targets to be displayed at different locations on a display screen and to determine from the pupil tracking system whether the subject'"'"'s pupil has moved in response to display of each target. In some embodiments, the pupil tracking system comprises an infrared camera.

Claims

1. A method for performing objective perimetry visual field testing of an eye of a subject, the method comprising:

providing, in combination, an eye tracking device, a computer device and one or more display screens connected to display;

displaying targets in sequence on one of the one or more display screens while the subject views the display screen with an eye under test; and

recording whether the eye under test moves in response to the presentation of a target.

2. A method according to claim 1, comprising testing only a central portion of the visual field of the subject'"'"'s eye.

3. A method according to claim 2, wherein the central portion includes 15°

, 20°

, 25°

, 30°

, 40°

, 50°

, 60°

, or 70°

from the direction of gaze of the eye.

4. A method according to claim 1 wherein recording whether the eye under test moves in response to the presentation of a target comprises determining a first angle and distance over which a point on the display at which the subject'"'"'s eye is gazing moves and comparing the first angle and distance to a second angle and distance between a current target and an immediately-preceding target.

5. A method according to claim 1, the method comprising:

creating an eye grid of an eye under test corresponding to a screen grid on the display device viewed by the subject;

displaying targets at different locations on the display device;

while presenting each target, activating first and second infrared illuminators and taking one or more pairs of camera images in sequence;

determining from the camera images a location on the eye grid and a corresponding location on the screen grid;

determining from the locations whether the subject'"'"'s eye has moved in response to presentation of a target;

storing the location of each target and whether the pupil moved in response to the presentation of the target; and

analyzing stored data to provide the perimetry visual field of the eye.

6. A method according to claim 1 wherein displaying targets includes starting each target as a single small point and then enlarging the target until an eye response occurs.

23. A method according to claim 1 wherein displaying targets includes starting each target at an initial brightness and then increasing the brightness until an eye response occurs.

7. Apparatus for performing objective perimetry visual field testing of an eye of a subject, the apparatus comprising:

an eye tracking device;

a computer having one or more display screens;

said computer comprising means for displaying targets in sequence on at least one of the one or more display screens while the subject views the display screen with an eye under test; and

said computer having a memory and configured to determine from an output of the eye tracking device and record in the memory whether the eye under test moves in response to the presentation of a target.

8. Apparatus according to claim 7 wherein the computer comprises a personal computer.

11. Apparatus according to claim 8 wherein said illuminators comprise infrared LEDs.

9. Apparatus for performing objective perimetry visual field testing of an eye of a subject, the apparatus comprising:

a display device for viewing by said subject;

a gaze detection system for detecting and tracking the pupil of an eye under test, said system including an infrared camera and associated first and second infrared illuminators which emit radiation substantially invisible to the human eye but detectable by the camera;

the first illuminator being closer to the optical axis of the camera than the second illuminator;

means for detecting from said images the location of a pupil of the eye under test;

a target generator for generating and displaying a sequence of targets on said display device;

a storage device for storing a location of each target and whether the eye moved in response thereto; and

means for processing stored target data to provide perimetry visual field of the eye.

10. Apparatus according to claim 9 wherein said gaze detection system further includes means for alternately capturing even and odd frames of camera images in synchronism with activation of said first and second illuminators.

12. Apparatus according to claim 9 wherein said first illuminator comprises a ring of light emitting diodes (LEDs) around the lens aperture of the camera.

13. Apparatus according to claim 12, wherein LEDs in said ring generate a bright pupil image and LEDs of the second illuminator generate dark pupil images.

14. Apparatus according to claim 9 wherein said target generator is operable to select a target somewhere in an eye grid of the eye under test, determine whether the selected target is within the screen grid, and if so, use the selected target as a next target.

15. Apparatus for performing objective, perimetry visual field testing of an eye of a subject, the apparatus comprising:

a computational apparatus;

a display device, viewed by a subject during a test, connected to said computational apparatus for displaying targets within a screen grid on said display device;

an infrared camera connected to said computational apparatus and which, during use, is directed toward an eye under test for taking images of the subject eye and transmitting said images to said computational apparatus;

first and second illuminators disposed to illuminate an eye under test;

a computer program product embodied in a machine readable medium, said program product being operable to cause said computational apparatus to display a sequence of targets at different points of said display device;

determine from said images the direction and point of gaze of an eye under test after each target has been displayed;

and store the location of each target and movement or lack of movement of the eye under test in response to the presentation of the target.

16. Apparatus according to claim 15 wherein the computer program product is operable to cause said computational apparatus to determine a perimetry of a field of vision of the eye under test.

17. Apparatus according to claim 15, wherein said illuminators include near infrared light sources and said camera being sensitive to a wavelength of said light sources.

18. Apparatus according to claim 17 wherein said illuminators comprise 16 IR light emitting diodes (LEDs) distributed in two concentric rings, with eight LEDs in each ring, the axis of the rings being coaxial with an optical axis of the camera, the diameter of the inner ring being approximately the same as the diameter of a lens of the camera, and the diameter of the outer ring being larger than the diameter of the inner ring.

19. Apparatus according to claim 17, wherein said illuminators comprise 16 IR light emitting diodes (LEDs) distributed in a ring and a pair of parallel lines, with eight LEDs in the ring and eight LEDs in the parallel lines, an axis of the ring being coaxial with an optical axis of the camera and the diameter of the ring being approximately the same as the diameter of a lens of the camera, and the parallel lines being spaced outwardly of the ring.

20. Apparatus according to claim 15 wherein said display device has a substantially flat screen.

21. Apparatus according to claim 15 wherein said computational apparatus comprises a personal computer.

22. A machine-readable medium having instructions stored thereon capable of causing a processor to carry out a method for performing objective, perimetry visual field testing of an eye of a subject, the method comprising:

a) initializing an infrared camera and an interface between the camera and a computational apparatus;

b) defining an eye grid by sequentially displaying a target at each corner of a display device;

c) recording the position of the pupil of an eye under test when it is viewing each of the four targets;

d) deriving a mapping between the position of the eye in the camera and the direction in which the eye is pointing;

e) displaying a target at the centre of the display device and assigning the location of the target to target t2;

f) setting the location of a target tl equal to the location of target t2;

g) generating a new target within said screen grid and assigning its location to target t2;

h) displaying target t2 on said display device for a predetermined period of time;

i) determining whether the eye has moved close to the location of target t2 and, if not, recording target t2 as failed and then repeating steps (g) onward; and

if so, recording target t2 as passed and repeating steps (f) onward until a target t2 is found that has failed; and

,

j) processing the recorded data to provide the result of an objective perimetry visual field of the eye under test after displaying a predetermined number of targets.