Evolution of geographic atrophy of the retinal pigment epithelium.

The aim of this study was to trace the evolution of geographic atrophy (GA) by clinical documentation and by clinico-morphological correlation in representative eyes. Geographic atrophy commonly commenced within a parafoveal band of incipient atrophy of varying width, characterised by semisolid drusen and a microreticular pigment pattern. Progression of atrophy mostly skirted fixation and visual acuity was a poor guide to the functional impact, an estimate of the percentage of fovea involved proving a more useful clinical parameter. The rate of progression slowed once GA had involved all the retina affected by incipient atrophy and the risk of choroidal neovascularization appeared to decline. An earlier histological classification of the evolution of GA is revised according to the ultrastructural findings. Membranous debris was not previously recognised and its contribution to the findings in incipient atrophy and to dot-like drusen is described.