Biomorphometry and histomorphometry of the optic disc with special reference to the parapapillary region.

Glaucomatous optic nerve damage is typically associated with intrapapillary changes such as neuroretinal rim loss. In this study, parapapillary chorioretinal atrophy was evaluated in 691 normal eyes, 1081 glaucomatous eyes and 31 eyes with ocular hypertension. It was significantly larger and occurred more often in the glaucomatous eyes (parapapillary atrophy area: 1.07 +/- 0.83 mm2) than in the normal eyes (0.55 +/- 0.64 mm2) or the eyes with ocular hypertension (0.55 +/- 0.37 mm2). These differences were significant also for eyes with moderate glaucomatous damage (0.86 +/- 0.62 mm2). Parapapillary chorioretinal atrophy was associated with shallow glaucomatous cupping, diffuse nerve fiber loss, markedly tessellated fundus and only moderately elevated intraocular pressure. It increased with decreasing neuroretinal rim area. It showed a spatial correlation to neuroretinal loss inside the optic disc. In unilateral glaucoma, it was larger in the affected eye than in the unaffected eye. Differentiated into zones Alpha and Beta, it correlated clinico-histologically with a complete loss of retinal pigment epithelium cells and incomplete loss of photoreceptors (Zone Beta) and pigmentary and structural irregularities of the retinal pigment epithelium (zone Alpha). Parapapillary chorioretinal atrophy is associated with glaucoma.