Optics: eye examining – vision testing and correcting – Eye examining or testing instrument – Objective type
Patent
1994-09-30
1996-08-27
Sikes, William L.
Optics: eye examining, vision testing and correcting
Eye examining or testing instrument
Objective type
351205, 351246, A61B 314
Patent
active
055506011
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a method of, and to apparatus for use in ocular motility testing.
U.S. Pat. No. 5,094,521 reveals an apparatus for ocular motility testing comprising head positioning means for location of the head of a patient in a predetermined position, gaze-detecting means adapted to image both eyes simultaneously with the patient's head in a predetermined position while the patients eye(s) follow a target on a screen, and computing means for computing the position of visual axis of said eyes with reference to a primary position, and store means associated with target display means and said computing means to store the positions of the target and the positions of the visual axis.
The present invention is characterised in that the gaze-detecting means is disposed adjacent the eyes of the patient and comprises left and right gaze direction detecting means acting independently.
In the inventive embodiment in accordance to the present invention the gaze-detecting means is disposed close to the eyes of the patient and comprises mutually independent left and right gaze direction detectors. The gaze-detecting means may also include gaze occluder means operable selectively to occlude a patient's eye relative to the target. The arrangement of the invention may include control means programmable to drive the projection means so that the target is either displayed at different positions or is moved dynamically along a predetermined path according to parameters said in the computer program.
In a preferred embodiment projection means is adapted to project an illuminated target onto a screen positioned symmetrically with regard to the primary position.
U.S. Pat. No. 5,094,521 also reveals a method of ocular testing comprising the steps of: to look at a target, position, ocular motility data.
The present invention is characterised in that said detecting step (a) comprises detection of the visual axes of both eyes of a patient instructed to look at a target by left and right gaze-detecting means positioned adjacent the patient. The target may be projected onto a screen symmetrically relative to said primary position, and wherein the target is projected from a position above the head of the patient. Step (a) may further comprise the simultaneous detection of the visual axis of both eyes of a patient instructed to look at the target. In a preferred form of the invention the visual axis of one eye of the patient is occluded during the testing procedure. The target may be moved in a series of preprogrammed steps, or may move dynamically along a predetermined path.
An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawing which is a diagrammatic representation partly in plan view of a system with apparatus for use in ocular motility testing in accordance with the present invention.
Ocular motility testing in the context of the present invention is concerned with the degree of accuracy or error in the direction of gaze of each eye of an observer instructed to look at a target displayed successively at different positions on a screen. Although such testing involves movements of the eyes to re-direct the gaze directions towards the different target positions, it should be understood that ocular motility test data consists essentially of static measurements for each specific target position. The present ocular motility testing is not concerned with dynamic measurements during eye movements. However, it is envisaged that ocular motility testing can feature a continuously moving target provided that the speed of movement is not too fast to prevent the obtaining of effective static measurements for different specific target positions.
In the drawing, the system apparatus features display means in the form a projector 10 adapted to project a target 11, being a spot of light, onto screen 12 which is positioned symmetrically with respect to a centre line 13 (primary position--looking straight ahead). An observer 14 is positioned immediately below the projecto
REFERENCES:
patent: 5070883 (1991-12-01), Kasahara
patent: 5094521 (1992-03-01), Jolson et al.
Dang Hung Xuan
Sikes William L.
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