97th DOG Annual Meeting 1999
LOCAL AND GLOBAL STEREOPSIS IN GLAUCOMA
R. Gockeln, A. Hentschel, U. Kretschmann, R. Winter
Glaucoma soon leads to a degeneration of retinal ganglion cells. In addition to abnormities in contrast sensitivity, color-vision and movement perception, in glaucoma there are disorders of depth perception. Compared to local stereopsis, global stereopsis seems to be affected in a different degree.
Methods: Patients with low-tension and open-angle glaucoma without signs of binocular disorders were compared to a control group with regard to their sensoric capacities. Criteria for the low-tension glaucoma were the glaucomatous optic disc and an intraocular pressure (IOP) of less than 21 mmHg, wheras cases with open-angle glaucoma were due to show a glaucomatous optic disc in combination with an IOP more than 21 mmHg. In addition to the perimetry (Octopus G1, MD) we assessed contrast, sensitivity, color-vision, depth perception (random-dot, contours) and the optic nerve fiber layer.
Results: The damage of retinal ganglion cells and their axons often leads to a significant decrease in global stereopsis long before there are perimetric defects. In contrast to that local stereopsis seems to be affected long after large perimetric disorders.
Summary: Global stereopsis disorders in glaucoma turn out to be the result of a damage of certain ganglion cells and their axons with decreased redundance in order to compensate defects (functional overlap of receptive fields).
Dept. of Ophthalmology, Hannover Medical School, Carl-Neuberg-Str. 1, D - 30625 Hannover, Germany