COMPARISON OF GANGLION-CELL LOSS AND CONE LOSS IN EXPERIMENTAL GLAUCOMA

PURPOSE: To compare the loss of ganglion cells to cone loss in the mac ular area of monkey eyes with experimental glaucoma. METHODS: Experime ntal glaucoma was induced in eyes of three cynomolgus monkeys by argon laser applications to the trabecular meshwork. The average duration /- S.D. of glaucoma in the experimental animals was 3.8 +/- 0.5 months . Glaucomatous damage was estimated, before the animals were killed, b y evaluating stereoscopic photographs of the optic disk and red-free p hotographs of the nerve fiber layer. Ganglion cell nucleoli and cone p edicles were counted by using light microscopy from slides containing strips of retinal tissue. Cell density was then calculated by using th e modified Abercrombie formula. Percent loss of ganglion cells and con es was determined from three eyes of three monkeys in 300-mu m segment s that were 900 to 1,200 mu m superior and inferior to the foveal cent er. RESULTS: Cone loss was not found at 4.5 to 6 degrees eccentricity above and below the fovea, whether damage was mild or severe. The aver age loss +/- S.D. of ganglion cells was 81.1% +/- 10.7%, whereas the a verage cone loss was only 3.5% +/- 6.4%. CONCLUSIONS: Marked parafovea l cone loss was not found in experimental glaucoma in which extensive damage to ganglion cells occurred.