Method and apparatus for measuring and correcting metamorphopsia

Abstract

A method and apparatus are provided for the evaluation and measurement of metamorphopsia. The apparatus includes a pattern generator that displays a deformable pattern, such as an Amsler grid, on a computer monitor. The rectilinear grid includes substantially parallel and equally spaced lines that intersect at vertices. An input device, such as a mouse, is used by a patient or technician to detect areas of the pattern where the cursor is not visible to the subject, so that areas of scotoma can be marked. The input device is also used to adjust the positions of the vertices, and distort the grid, until the grid appears substantially rectilinear to the subject. The deformations of the pattern are then recorded, and can be retrieved for comparison to subsequent test results so that changes in visual field deficits or metamorphopsia can be sensitively detected, and even corrected by a lens that distorts images in the same pattern. The present invention provides a very sensitive test for metamorphopsia that detects early retinal changes at a time when therapeutic intervention may be more helpful. The test can also be conveniently used at home, for example on a personal computer, so that the subject can be tested frequently and easily. The results of the test are mathematical maps or functions (image distortion as a function of image location) that can be used to provide therapeutic correction of metamorphopsia.