Method for visual field testing

• US 7,988,288 B2
• Filed: 12/21/2007
• Issued: 08/02/2011
• Est. Priority Date: 12/22/2006
• Status: Expired due to Fees

• Current Assignee: IbisVision Limited
• Original Assignee: Bid Instruments Limited
• Inventors: Donaldson, Blair
• Primary Examiner(s): HASAN, MOHAMMED A
• Application Number:
  US12/520,834
• Publication Number:
  US 20100128222A1
• Time in Patent Office: 1,320 Days
• Field of Search: 351200-246
• US Class Current: 351/210
• CPC Class Codes: A61B 3/0091 Fixation targets for viewing direction
• 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

A method of ocular testing is provided using a testing apparatus having a display (2) and a control means (6, 17) for controlling movement of a cursor (7). The method comprises providing a fixation target (T), detecting when an observer (1) moves the cursor (7) over the fixation target, and once the cursor has been moved over, providing a new target on the display (2). The observer (1) is then encouraged to move the cursor (7) over the new target, this then becoming the fixation target. If the observer (1) does not move the cursor (7) over the new target, it is determined that the new target falls outside the observer'"'"'s visual field. The above is then repeated to build up a visual field of the observer (1) based on the detected and undetected target positions.

Claims

1. A method of ocular testing using a testing apparatus having a display and observer controllable means for controlling movement of a cursor on the display, the method comprising the steps of:

providing a fixation target on the display at a known target position;

detecting when an observer moves the cursor over said fixation target;

once the cursor is over the fixation target, providing a new target on the display at a further known target position;

detecting if an observer moves the cursor over said new target, the new target then becoming the fixation target;

determining that the new target falls outside the observer'"'"'s visual field if the observer does not move the cursor over the new target;

repositioning the new target if it is determined that the new target falls outside the observer'"'"'s visual field, until it is detected that the observer has been able to move the cursor over the new target, the new target then becoming the fixation target;

recording the detected and undetected target positions;

and repeating the steps of providing a new target on the display a number of times to build up a visual field of the observer based on the detected and undetected target positions.

2. A method according to claim 1, wherein a new target not seen by the observer is repositioned after a predetermined time interval.

3. A method according to claim 1, wherein a new target not seen by the observer is moved in incremental steps.

4. A method according to claim 1, wherein the means for controlling the cursor is an electronic pen and pad arrangement or a mouse.

5. A method according to claim 1, wherein the cursor is a circle moveable for surrounding the fixation target.

6. A method according to claim 1, wherein the size, shape and/or position of the fixation target is configured to change for engaging the observer.

7. A method according to claim 1, wherein the fixation target is arranged to move and the observer is encouraged to track said movement by maintaining the cursor over the fixation target;

and wherein the new target is only displayed when the cursor is over the fixation target or being moved directly towards the new target;

and wherein the new target moves with said fixation target to maintain it at a constant position relative to the fixation target until the cursor is moved over the new target.

8. A method according to claim 7, wherein the fixation target moves in a random pattern.

9. A method according to claim 7, wherein the fixation target moves in a regular pattern.

10. A method according to claim 1, further comprising the step of repositioning the fixation target whilst the observer maintains the cursor over the fixation target for creating additional space on the display for displaying the new target or a subsequent new target.

11. A method according to claim 10, wherein the step of repositioning the new target falling outside the observer'"'"'s visual field is performed after a predetermined time interval.

12. A method according to claim 1, the method further comprising the steps of providing a blind spot target in a position relative to said fixation target which is known to be in the observer'"'"'s blind spot;

determining that the observer has lost fixation on said fixation target if they move the cursor over said blind target;

instructing the observer to return the cursor to the fixation target when it is determined they have lost fixation;

and removing said blind target when the observer moves the cursor over said fixation target.

13. A method according to claim 1, the method further comprising conducting a pre-test calibration procedure, said pre-test calibration procedure comprising the steps of:

providing a pre-test fixation target on the display at a known target position;

detecting when an observer moves the cursor over said pre-test fixation target and encouraging the observer to continue to look at the pre-test fixation target;

once the cursor is over the pre-test fixation target, providing a contrast target on the display at a different position to said pre-test fixation target, said contrast target having a low contrast relative to the background of the display;

encouraging the observer to move the cursor over said contrast target to identify the contrast target;

increasing the contrast of said contrast target relative to said background until the observer identified the contrast target;

recording the contrast level at which the observer identifies the contrast target; and

repeating the above steps until a threshold for recognition of the contrast target relative to the background is determined.

14. A method according to claim 13, the step of recording the contrast level at which the observer identifies the contrast target further comprises the step of recording the time taken for an observer to identify a supra-threshold target and using that data to determine the observer'"'"'s reaction time.

15. A method according to claim 1, the method further comprising conducting a pre-test calibration procedure, said pre-test calibration procedure comprising the steps of:

providing a pre-test fixation target on the display at a known target position;

detecting when an observer moves the cursor over said pre-test fixation target;

once the cursor is over the pretest fixation target, providing a new target on the display at a further target position;

detecting if the observer moves the cursor over said new target and how long it takes for the observer to move the cursor over said new target from when it is displayed, the new target then becoming the pre-test fixation target;

repeating the above steps to calibrate the observer'"'"'s speed of response.

16. A method according to claim 1, wherein the method incorporates the step of detecting whether or not the observer is keeping their gaze on the fixation target using a gaze detection means.

17. A method according to claim 16, further comprising the step of pausing the test if the gaze detection means detects that the observer is not keeping their gaze on the fixation target.

18. A method according to claim 16, wherein the gaze detection means comprises a video camera and suitable software.

19. A method according to claim 1, wherein results from the method are recorded in graphical or pictorial form, representing the visual field of the observer.

20. A method according to claim 19, wherein the results from testing the same observer at different times or different target contrast levels are superimposable.

21. A method according to claim 1, wherein information relating to the test is provided on a single screen, suitably screened off between an observer and an Examiner.