Abstract
Purpose :
There has been a surge in interest recently around the role of subretinal fibrosis on the long-term visual outcome of patients with Wet Age-Related Macular Degeneration (AMD) on treatment with anti-vascular endothelial growth factors (anti-VEGF). Detailed phenotyping of subretinal fibrosis is essential to identify markers for response to treatment. Optical Coherence Tomography Angiography (OCTA) is a novel imaging tool that can contribute useful clues to the understanding of subretinal fiborosis in the context of multi-modal imaging.
Methods :
This was a retrospective case-series on the analysis of OCTA images acquired with the DRI OCT Triton (Topcon Corporation, Tokyo, Japan). Consecutive patients attending for treatment of Wet AMD with evidence of subretinal fibrosis on the basis of clinical examination and OCT (hyper-reflective material under the retina/RPE) underwent OCTA imaging. Poor quality images due to motion artifacts were excluded from analysis. Images were analysed for presence of visible Choroidal Neovascularisation (CNV), CNV pattern, severity of fibrosis on colour fundus image (mild, moderate, severe), maximum thickness of hyper-reflective material on OCT. A linear regression for the influence of any of these features on visual acuity recorded on the visit of OCTA imaging was performed.
Results :
52 consecutive patients with subretinal fibrosis had OCTA imaging. Of those, 30 were deemed of adequate quality to include in subsequent analysis. A CNV was detectable on OCTA in 23 cases while it was absent in 7. When present, CNV fell into one of three categories: large, mature tangled vessels (10), small vascular loop (3) or a 'dead tree' pattern (10). Average VA was 45.48 letters. VA was independently adversely influenced by presence of visible CNV on OCTA (p=0.02) after accounting for severity of fibrosis and thickenss of hyper-relfective material on OCT. There was a weak positive correlation between severity of fibrosis and increasing OCT thickness of hyper-reflective material.
Conclusions :
OCTA contributes to phenotyping of subretinal fibrosis by offering information on vascularity of the fiboritc material, not available on colour fundus images or OCT. The combination of structural and flow information provided can improve characterisation of fibrosis. Presence of CNV on OCTA may be a negative prognosticator for vision in the context of subretinal fibrosis.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.