Optical coherence tomography in geographic atrophy--a clinicopathologic correlation

Abstract

Optical coherence tomography was used for the examination of patients with geographic atrophy in different stages of age-related macular degeneration. Always compared with biomicroscopy and fluorescein angiography [4,7,8,10]. 37 patients with geographic atrophy (n = 55 eyes) out of 150 with AMD (n = 169 eyes) were examined. The results of biomicroscopy, fluorescein angiography, optical coherence tomography and histological knowledge in age-related macular degeneration were studied. Fluorescein angiography always identified geographic atrophy and in 13.5% the findings additionally were similar to an occult choroidal neovascularisation with circular hyperpigmentation. Geographic atrophy shows a significant thinning of the neurosensory retina of 135 microns as an average in optical coherence tomography (p < 0.0005) which did not correlate to visual acuity. Typically an enhanced vertically sharp demarcated reflectivity of the choroid is found because of the lacking pigment epithelium. 43% of the geographic atrophies were identified by optical coherence tomography. 3 out of 55 eyes (5%) in optical coherence tomography only show macular holes additionally to geographic atrophy. A typical pattern of reflectivity is found by optical coherence tomography with enhanced reflectivity of the choroid because of lacking pigment epithelium and significant thinning of the fovea. Atypical macular holes moreover are found in 5% neither appearing in biomicroscopy nor in fluorescein angiography. An occult choroidal neovascularisation can be differentiated by optical coherence tomography from geographic atrophy because there is no spindle-like thickening of the pigment epithelium and no enhanced choroidal reflectivity. In borderline cases optical coherence tomography may be helpful and therapeutically decisive in differentiating geographic atrophy and occult choroidal neovascularisation and in detecting atypical macular holes.