Volume Rendering of Deep Retinal Age-Related Microvascular Anomalies

Abstract

Purpose: To characterize and distinguish non-neovascular deep retinal age-related microvascular anomalies (DRAMA) from type 3 macular neovascularization (MNV) using volume rendering of OCT and OCT angiography (OCTA).

Design: Retrospective, consecutive case series.

Subjects: Consecutive patients with age-related macular degeneration (AMD) exhibiting de novo non-neovascular abnormalities within the deep vascular plexus (DCP), as detected using high-resolution (High-Res) spectral-domain (SD) and swept-source (SS) OCT or OCTA. Patients with retinal vascular alterations attributable to other disease entities were excluded.

Methods: Complete ophthalmic examination and multimodal imaging, including confocal fundus photography (CFP), SD-OCT, High-Res SD-OCT and OCTA, and volume-averaged SS-OCTA. The volume renderings of High-Res OCTA and averaged SS-OCTA were used to analyze capillary abnormalities and inflow or outflow connectivity pathways.

Main outcome measures: The primary outcomes were the characteristics of capillary abnormalities (number, size, shape, reflectivity, and location) and inflow or outflow connectivity pathways. The secondary outcomes were nearby changes in CFP and structural OCT (hyperreflective foci [HRF], outer retinal atrophy, and retinal pigment epithelium [RPE] atrophy).

Results: From 8 eyes of 8 patients, 2 subtypes of DRAMA were identified: small-diameter perifoveal capillary dilations with hyperreflective walls within the inner nuclear layer (type 1, n = 4) and vascular outpouchings, typically multiple, extending posteriorly into the Henle fiber layer, with reflectivity similar to adjacent normal retinal capillaries (type 2, n = 10). Four eyes had both subtypes of DRAMA. The 3-dimensional visualization of OCTA data demonstrated DRAMA corresponding to the dilations of DCP capillaries without direct inflow or outflow connections to the superficial plexus. Fundus photographs showed circular red dots in 3 eyes, all corresponding to type 1 DRAMA. In all the cases, DRAMA colocalized with HRF. No lesions were found anterior to the areas of the RPE or outer retina atrophy. Asymptomatic intraretinal exudation varied through a follow-up duration of up to 6 years, with no lesions progressing to type 3 MNV.

Conclusions: In eyes with non-neovascular AMD, DRAMA include 2 types of capillary dilations occurring without the remodeling of the surrounding vascular network. Deep retinal age-related microvascular anomalies can resemble microvascular changes due to other causes and can masquerade as type 3 MNV. Mild intraretinal exudation can vary during follow-up, without progression to type 3 MNV.

Keywords: Deep capillary plexus; Intraretinal exudation; Non-neovascular age-related Macular degeneration; Type 3 Macular Neovascularization; Vascular anomalies.