Peripapillary chorioretinal atrophy: Bruch's membrane changes and photoreceptor loss

Abstract

Purpose: To determine relationships among Bruch's membrane ultrastructure, photoreceptor degeneration, and choriocapillaris atrophy with respect to zones of retinal pigment epithelium (RPE) degeneration and atrophy adjacent to the optic nerve head, as a function of age.

Design: Human tissue study using clinicopathologic correlation. TISSUES: Eyes from patients 36 to 93 years of age lacking clinical evidence of glaucoma, optic nerve abnormalities, severe myopia, age-related macular degeneration, or other macular or peripapillary chorioretinal pathologic condition.

Methods: Sections through the retina-choroid complex at the temporal aspect of the optic nerve head were used for light microscopic histopathologic analysis (n = 17), electron microscopy (n = 9), carbonic anhydrase histochemical analysis (n = 7), and lipid histochemical analysis (n = 22). Retinal whole mounts were used for photoreceptor counts (n = 5).

Main outcome measures: We determined the width of RPE degeneration and atrophy, the number of eyes with abnormalities of inner Bruch's membrane, and the number of rod and cone photoreceptors within 1 mm of the disc margin. We determined whether Bruch's membrane changes, photoreceptor degeneration, and choriocapillaris atrophy were associated with RPE degeneration and atrophy.

Results: All eyes had peripapillary RPE atrophy, degeneration, or both. The zone of RPE atrophy widened significantly after age 75. Thickening of inner Bruch's membrane and abnormalities of the RPE basal lamina were associated with degenerating and atrophic RPE in all eyes. The RPE basal lamina was narrow, reduplicated, or thickened as a basal laminar deposit. All eyes exhibited degeneration and loss of rods but not cones at the peripapillary termination of Bruch's membrane. Diminution of choriocapillaris coverage of Bruch's membrane was associated with RPE degeneration. Complete loss of the choriocapillaris was associated with RPE atrophy.

Conclusions: Our results suggest that peripapillary chorioretinal atrophy is an age-related degeneration of the RPE-Bruch's membrane complex that resembles that found in the macula and periphery of normal eyes.