Prevalence of outer retinal tubulation in eyes with choroidal neovascularization.

Background: Outer retinal tubulations (ORTs) are branching tubular structures located in the outer nuclear layer of the retina. The goal of this study is to determine the prevalence of ORTs observed in eyes with choroidal neovascularization (CNV) undergoing treatment with anti-angiogenic intravitreous injection (IVI) with anti-VEGF (vascular endothelial growth factor) at the Ophthalmology Department of a tertiary hospital in São Paulo, Brazil.

Methods: This is a descriptive study based on medical charts and Spectral-domain Optical Coherence Tomography (Sd-OCT) scans of 142 patients (158 eyes) treated between 2012 and 2014 with IVI of anti-VEGF for CNV. The patients' data was analysed according to age, gender, pathology, presence of ORTs, and best corrected visual acuity (BCVA). Patients with and without ORTs were compared according to the last BCVA obtained using Chi square corrected by the Yates factor.

Results: ORTs were found in a total of 40 out of 158 eyes (25.31 %) with CNV; in 33 out of 119 eyes (27.7 %) with neovascular age-related macular disease (AMD); in 5 out of 8 eyes (62.5 %) with neovascular angioid streaks; and in 2 out of 12 eyes (16.67 %) with myopic neovascular membranes. Most patients with ORTs had BCVA worse than 20/200, significantly worse BCVA than patients without ORTs.

Conclusions: Recent studies have considered that the presence of ORTs is indicative of a photoreceptor degeneration process and may represent a final stage of multiple retinal degenerative pathologies. The prevalence of ORTs in eyes with CNV has not been well described, especially when considering the Brazilian population treated in a public health care system. In our study, ORTs were observed in only three different pathologies: neovascular AMD, neovascular angioid streaks and myopic neovascular membranes. The correct recognition of ORTs is fundamental for its differentiation from intraretinal cysts, for the latter is related to the activity of neovascular diseases, and usually guides anti-angiogenic therapy. We conclude that ORTs have a high prevalence in the population studied, and their correct identification presents relevant therapeutic implications.