Optic disc histomorphometry in normal eyes and eyes with secondary angle-closure glaucoma. II. Parapapillary region.

Parapapillary atrophy has been reported to occur in glaucoma eyes. Seeking the microscopical equivalent, we evaluated histomorphometrically serial sections of 21 human eyes enucleated due to secondary angle-closure glaucoma and 28 nonglaucomatous eyes with malignant choroidal melanoma. In the parapapillary region two zones were differentiated: in zone "B" adjacent to the optic disc, Bruch's membrane was denuded of retinal pigment epithelium cells; zone "A" peripheral to zone "B" showed pigment irregularities in the retinal pigment epithelium. Both zones "B" and "A" were significantly larger and zone B occurred more frequently in glaucomatous eyes than in the control group. Additionally, the outer and inner retinal layers and the parapapillary retina as a whole were significantly thinner in the glaucoma eyes than in the control eyes. Photoreceptors were completely lost or markedly decreased in number in zone "B." The findings may indicate that zones "B" and "A" represent the histological correlate of the glaucomatous parapapillary chorioretinal atrophy.