Detailed Vascular Anatomy of the Human Retina by Projection-Resolved Optical Coherence Tomography Angiography

TLDR

OCTA provides noninvasive 3‑D imaging of retinal and choroidal vessels, yet depth discrimination is hampered by projection artifacts from superficial vessels, a limitation corroborated by histologic studies of retinal plexuses. The study aims to establish an enhanced nomenclature and segmentation scheme for 3‑D retinal vascular anatomy using OCTA, facilitating future research on normal and pathological retinal vasculature. Using a projection‑resolved OCTA algorithm that eliminates projection artifacts while preserving true flow signals, the authors derived a refined nomenclature and segmentation boundaries for retinal vascular layers. The enhanced imaging revealed 2–4 distinct retinal vascular plexuses whose presence varies with location relative to the optic disc and fovea, confirming the improved depth resolution of the technique.

Abstract

Abstract Optical coherence tomography angiography (OCTA) is a noninvasive method of 3D imaging of the retinal and choroidal circulations. However, vascular depth discrimination is limited by superficial vessels projecting flow signal artifact onto deeper layers. The projection-resolved (PR) OCTA algorithm improves depth resolution by removing projection artifact while retaining in-situ flow signal from real blood vessels in deeper layers. This novel technology allowed us to study the normal retinal vasculature in vivo with better depth resolution than previously possible. Our investigation in normal human volunteers revealed the presence of 2 to 4 distinct vascular plexuses in the retina, depending on location relative to the optic disc and fovea. The vascular pattern in these retinal plexuses and interconnecting layers are consistent with previous histologic studies. Based on these data, we propose an improved system of nomenclature and segmentation boundaries for detailed 3-dimensional retinal vascular anatomy by OCTA. This could serve as a basis for future investigation of both normal retinal anatomy, as well as vascular malformations, nonperfusion, and neovascularization.