Outer retinal tubulation may result from fibrosed type 2 neovascularization: clinical observations and model of pathogenesis.

PURPOSE To investigate the role of type 2 macular neovascularization with subsequent subretinal fibrosis in the pathogenesis of outer retinal tubulation (ORT). METHODS We conducted a retrospective cohort study of patients with stabilized inactive exudative macular degeneration who had been treated with intravitreal injections of anti VEGF agents. Baseline fluorescein and OCT images were included. MNVs were classified by type and size. Consecutive OCT images analysed for ORT development. RESULTS 144 eyes of 134 patients were included in this study. Sixty eyes presented with pure type 1 MNV. Eighty four eyes presented with some type 2 component to MNV. In total, evidence of ORT is shown in 55 (38%) eyes. In the Type-1 group, 6.7% developed ORT. ORT developed in 61% of eyes with some Type-2 component to the MNV. Among eyes that developed ORT, 92.7% presented with some Type-2 component. In a multivariate analysis, type-2 membranes on OCT (22.2 [6.1-80.8]; P 1DA(5.1 [1.1-24.2]; P=0.041) and >1.5DA (9.0 [1.8-44.0]; P=0.007), and presence of subretinal fibrovascular material (3.1 [1.1 - 8.5]; P=< 0.03), are associated with higher odds of ORT formation. Once the ORT is formed, fibrosis was observed directly underlying the ORT on SD-OCT in 70.9% of cases. CONCLUSION Type-2 membranes at presentation predicts ORT formation. Fibrosis often underlies ORT. This suggests contraction of type-2 MNV derived fibrosis may be important in ORT formation.