Quantification of metamorphopsia in patients with macular hole

PURPOSE. To describe a novel method for the evaluation of metamorphopsia within the central 10 of the visual field in 55 patients with idiopathic macular hole. The test evaluates the interocular disparity between the two eyes in metamorphopsia. METHODS. Semicircular test and reference stimuli of variable diameters were used in a binocular test that measured interocular size disparity between perceptually iseikonic stimuli in subjects with a unilateral macular hole. A group of 11 healthy subjects was used as the reference. RESULTS. In 55 patients with a macular hole, interocular disparity demonstrated a mean value of 0.71 degrees with stimuli in the range 1.0 degrees to 2.5 degrees in diameter. This number declined to 0.41 degrees with stimuli in the range of 9.0 degrees to 10.0 degrees in diameter. Both hole diameter and eccentricity had a significant effect on mean disparity (P < 0.001). CONCLUSIONS. The level of metamorphopsia declined as a function of eccentricity and affected the central 10 of visual field. Macular hole size had an independent effect on interocular disparity. These results confirm reports that visuospatial distortion in the presence of macular hole is primarily the result of radial displacement of photoreceptors.