PRECURSORS OF TYPE 3 NEOVASCULARIZATION

Abstract

To study the advent of exudative age-related macular degeneration in uninvolved fellow eyes of patients with unilateral Type 3 neovascularization and to investigate the precursors at the site of lesion development. We studied 37 consecutive patients with the diagnosis of unilateral Type 3 neovascularization, for the advent of exudative age-related macular degeneration in uninvolved fellow eyes (study eyes). Looking for the precursors of Type 3 neovascularization, we reviewed the multimodal imaging (fundus autofluorescence, fluorescein angiography, indocyanine green angiography, and spectral-domain optical coherence tomography) in the study eyes and interpreted the changes over time at the site of lesion development. Of the 37 patients, 12 (32%) developed exudative age-related macular degeneration in the study eye, after a mean of 19.6 ± 9.5 months (range, 9-36 months) from the diagnosis of Type 3 neovascularization in the first involved eye (baseline). All these patients (12 of 12 eyes; 100%) developed Type 3 neovascularization in the study eye. Retrospective analysis of the precursors of these lesions revealed, at baseline, a focal hyperautofluorescence (fundus autofluorescence) that turned to focal hypoautofluorescence over time. In all eyes, a focal hyperfluorescence (fluorescein angiography and indocyanine green angiography) appeared over time at the site of Type 3 neovascularization development. The corresponding spectral-domain optical coherence tomography showed a localized retinal pigment epithelial (RPE) elevation characterized by a focal disruption of the RPE and photoreceptors and by the overlying outer plexiform layer that progressively took contact with the RPE. Based on these findings, it seems that a small, localized RPE elevation might be the lesion before the development of Type 3 neovascularization. This precursor lesion progresses over time to focal atrophy of RPE and photoreceptor. Type 3 neovascularization presents a predictable symmetry and bilaterality. Identification of the precursors of Type 3 neovascularization looks particularly useful for clinicians to detect the earliest changes in the vasogenic process in the fellow eye.