Quantification of the Brückner test for strabismus.

PURPOSE To measure quantitatively the change in the coaxial fundus reflex with varying degrees of ocular misalignment. METHODS The coaxial fundus reflex was imaged with a charge coupled device camera under conditions of simulated ocular misalignment ranging from 0 degrees to 7 degrees of fixation eccentricity. The effects of refractive error and pupil size were controlled. Average gray scale brightness values were calculated for each bright pupil image after some image processing was performed on the raw images. RESULTS A reliable, sharply delineated, minimum brightness at foveal fixation was observed. CONCLUSIONS It is estimated that this technique can be automated to detect the presence of 2 degrees to 3 degrees of ocular misalignment based on the difference in brightness of the bright pupil images between the two eyes.