Prevalence of Quiescent Neovascularization in Intermediate and Late Non-Exudative Age-Related Macular Degeneration and the Incidence of Subsequent Exudation using Swept-Source Optical Coherence Tomography Angiography

Abstract

Purpose : Swept-source optical coherence tomography angiography (SS-OCTA) imaging of eyes with non-exudative age-related macular degeneration (AMD) was performed to determine the prevalence of quiescent choroidal neovascularization (CNV) and to detect the onset of exudation in these eyes.

Methods : In this prospective, observational, consecutive case series, patients with intermediate AMD (iAMD) or geographic atrophy (GA) secondary to non-exudative AMD in one eye and a history of exudative AMD in the fellow eye were imaged using both the 3mm x 3mm and 6mm x 6mm SS-OCTA field of views (FOVs) (PLEX Elite 9000, Carl Zeiss Meditec). The en face slab used to detect the CNV extended from the outer retina to the choriocapillaris (ORCC slab), and projection artifacts were removed using a proprietary algorithm. The time to exudation was determined and Kaplan-Meier methods were used to calculate the cumulative incidence of exudation.

Results : SS-OCTA imaging was performed on 152 patients (111 eyes with iAMD and 41 eyes with GA) from August 2014 through October 2016. Quiescent CNV was found in 20 of the iAMD eyes (18%) and seven of the eyes with GA (17%). A total of 11 eyes of the 152 eyes developed exudation, and 10 of the 11 eyes developing exudation were previously diagnosed with quiescent CNV. The one eye developing exudation that was not diagnosed with a pre-existing neovascular lesion had not been imaged for 19 weeks prior to the onset of exudation. By 12 months of follow-up, the cumulative incidence of exudation in all 152 eyes was 8.7%, and by 24 months, it was 27.3%. In those eyes with quiescent CNV, 29.7% developed exudation by 12 months. At 12 months, there was no difference in the predicted cumulative onset of exudation from pre-existing CNV in eyes with either iAMD or GA (p=0.89, log-rank test).

Conclusions : The prevalence of quiescent CNV and the cumulative onset of exudation by 12 months were similar in eyes with either iAMD or GA. Except for one eye with inadequate follow-up, all the eyes developing exudation over 24 months were found to contain quiescent CNV suggesting that most if not all exudative disease arises from pre-existing neovascularization that can be detected using SS-OCTA.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.