Volume-Rendering Optical Coherence Tomography Angiography of Macular Telangiectasia Type 2

Abstract

Purpose: To evaluate the vascular structure of eyes with macular telangiectasia type 2 (MacTel2) using volume-rendered optical coherence tomography angiography (OCTA).

Design: Retrospective cross-sectional study.

Participants: A total of 14 consecutive patients (20 eyes) with MacTel2 who had a signal strength score ≥55 and could maintain fixation during the scan process.

Methods: The eyes were scanned using optical coherence tomography with split-spectrum amplitude decorrelation techniques to derive flow information. Data were extracted and used to create volume-rendered images of the retinal vasculature that could be rotated about 3 different axes for evaluation.

Main outcome measures: Descriptive appraisal of the vascular abnormalities associated with MacTel2.

Results: Vessels posterior to the outer boundary of the deep retinal plexus were secondary to retinal thinning, vascular invasion, or a combination of both. These vessels had the same shape and distribution as the late staining seen during conventional fluorescein angiography. Lateral contraction in the temporal macula in 5 eyes created an appearance of vessels radiating from a central locus, which was the site of a right angle vein. Loss of macular tissue as part of the disease process led to a central amalgamation of the inner vascular plexus and the deep vascular plexus, which appeared to be in a state of decline. Subretinal neovascularization originated from the retinal circulation but involved not only the subretinal space but also could infiltrate the remaining, thinned, retina.

Conclusions: Volume rendering of OCTA information preserves the 3-dimensional relationships among retinal vascular layers and provides opportunities to visualize retinal vascular abnormalities in unprecedented detail. The retinal vascular leakage and invasion in MacTel2 may arise as a consequence of loss of control with depletion of Müller cells and exposure of the remaining retinal vessels to the more hypoxic environment near the inner segments of the photoreceptors.