Morphological Analysis of Type 1, Type 2, and Type 3 Neovascularization in Exudative Age-Related Macular Degeneration using OCT Angiography

Abstract

 

Purpose

 

To describe and compare the morphological structure of Type 1, Type 2, and Type 3 neovascularization in exudative age-related macular degeneration (AMD) using optical coherence tomography (OCT) angiography.

 

Methods

 

This was a retrospective, cross-sectional, observational study of patients with neovascular AMD. All patients underwent imaging with spectral-domain OCT and OCT angiography (Optovue AngioVue System). Type 1, 2, and 3 neovascularization was identified with high-resolution spectral-domain OCT and the correlative anatomical features of these lesions were then studied using OCT angiography.

 

Results

 

A total of 31 eyes of 26 patients with neovascular AMD were imaged with structural and flow-based OCT protocols. Type 1 (sub-retinal pigment epithelium; sub-RPE) neovascular membranes associated with vascularized pigment epithelial detachments (PEDs) or chronic multilayered PEDs were identified in 23 eyes. Type 2 (subretinal) neovascularization was found in 1 eye, and Type 3 neovascularization (retinal angiomatous proliferation; RAP) was studied in 8 eyes. In every case of Type 1 neovascularization, a plaque of thick vessels beneath the RPE could be identified regardless of whether there was associated intraretinal, subretinal, or sub-RPE fluid. In eyes with chronic multilayered PEDs, these vessels could be identified along the RPE monolayer above an organized scar. Type 2 neovascularization demonstrated a bright spoke-wheel arrangement of subretinal vessels that corresponded to a hyper-reflective plaque on structural OCT. Type 3 neovascularization varied in OCT angiographic appearance with 2 cases demonstrating sub-RPE vessels, 3 cases showing a focal tuft of fine vessels at the level of the RPE, and two without detectable vessels. These distinct manifestations appeared to be independent of the activity of the lesion, the treatment status, or the presence of fluid.

 

Conclusions

 

OCT angiography is a new imaging modality capable of revealing the morphological structure of Type 1, Type 2, and Type 3 neovascularization in exudative AMD. Studies are ongoing to detect anatomic features that indicate neovascular activity and how these may be altered with treatment.  

 

Type 1 neovascular membrane beneath a chronic multilayered PED with overlying subretinal fluid.

 

 

Type 2 neovascular membrane above the RPE with a spoke-wheel arrangment of vessels.