Occult chorioretinal anastomosis in age-related macular degeneration: a prospective study by optical coherence tomography.

PURPOSE To investigate macular optical coherence tomography (OCT) features in patients with chorioretinal anastomosis (CRA) and drusen, as well as their correlation with the Gass occult-CRA hypothesis. DESIGN Prospective observational case series. METHODS setting: Tertiary ophthalmic referral center. study population: All patients with biomicroscopic evidence of CRA and drusen consecutively evaluated between February 2003 and March 2004. observation procedures: Third-generation OCT evaluation and stereoscopic angiographic studies. main outcome measures: Macular morphologic features at baseline and at 12 weeks. RESULTS Twenty eyes with CRA and drusen were identified in 11 patients, seven women (63.6%) and four men (36.4%) ranging in age from 69 to 82 years (median, 79 years). Focal elevation of the retinal pigment epithelium was seen in eyes with stage 1 (pre-clinical) CRA. Small hyperreflective signals at the level of the elevated retinal pigment epithelium were seen in stage 2 CRA. In stage 3 CRA, a hyperreflective "mound" at the level of the elevated retinal pigment epithelium was seen in association with a thickened retina. In stage 4 CRA sub-retinal pigment epithelium fluid accumulation was present, and complete disorganization of the macular region was observed in stage 5 CRA. Macular changes were observed in eight eyes (40%) at follow-up, with all but one CRA lesion progressing one stage. CONCLUSION Morphologic features and changes demonstrated by OCT suggest that fibrovascular detachment of the retinal pigment epithelium followed by development of occult CRA are the initial events occurring in eyes with CRA in age-related macular degeneration. Our findings may support the evolutionary CRA staging system proposed by Gass.