Abstract
Purpose :
To identify the location of the retinal capillary layers in a healthy population and their relative relationship in images obtained by Optical Coherence Tomography Angiography (OCT-A).
Methods :
A set of 25 eyes from 13 healthy volunteers between 50 and 72 years of age (m±SD:60.46±6.67) were acquired on the OCT Cirrus 5000 AngioPlex (Carl Zeiss Meditec, Dublin, California, USA) using the HD Angio 3x3 protocol. To identify the different retinal layers, the volume scans were segmented using a semi-automated procedure developed in-house to identify 8 retinal interfaces namely Vitreous to Inner Limiting Membrane (ILM), Retinal Nerve Fiber to Ganglion Cell Layers, Inner Plexiform to Inner Nuclear Layers (INL), INL to Outer Plexiform Layer (OPL), OPL to Outer Nuclear Layer (ONL), Inner Segment (IS) to Outer Segment (OS), OS to Retinal Pigment Epithelium (RPE) and RPE to Choroid. Customized identification of the retinal capillary networks was also performed. Location of the retinal capillary networks was identified in the different layers and their distance from the ILM was measured.
Results :
The Superficial Capillary Network (SCN) shows a smaller Foveal Avascular Zone and is identified in healthy eyes in a slab comprised between 51.5±7.6 µm and 93.4±8.0 µm from the ILM in the parafovea region. The Deep Capillary Network (DCN) is located deep in the retina in the slab located between 105±11.0 µm and 190±15.2 µm from the ILM in the parafovea region. The larger vessels are mainly located superficial to these capillary networks in a slab close to the ILM. There are interconnecting capillaries between both capillary networks mainly perpendicular and crossing the retina between the SCN and DCN slabs that could be interpreted as an additional network.
Conclusions :
Custom segmentation allows improved characterization of the retinal capillary networks and their location. Clear identification of the superficial and deep capillary networks in healthy eyes is fundamental for improved understanding of retinal vascular disease and its progression.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.