Swept-Source OCT Angiography Characterization of Macular Telangiectasia Type 2 Spectrum.

Abstract

Purpose : To investigate the retinal microvascular and choriocapillaris changes in the recently proposed 7-step classification for Macular Telangiectasia type 2 (MacTel) employing swept-source optical coherence tomography angiography (SS-OCTA).

Methods : Cross-sectional, observational study including MacTel eyes with visual acuity >20/200, good-quality macular SS-OCTA (signal strength index >7, no artifacts) and no other ocular/systemic comorbidities. MacTel eyes were categorized into one of the 7 grades (0-6) proposed by the MacTel Project based on multimodal imaging. 6x6-mm OCTA scans (PLEX Elite 9000; Carl Zeiss Meditec, Dublin, CA) were processed using the macular density algorithm (v.0.7.3.3) on the Advanced Research and Innovation (ARI) Network portal to measure vessel density (VD) and vessel skeletonized density (VSD). Choriocapillaris was analyzed in FIJI by measuring inner choroidal flow deficit percentage (ICFD%) for 15-µm slabs, after compensation and binarization with Phansalkar method (r=15). All analyses were performed for 6-, 3- and 1-mm circles and various ETDRS sectors. Kruskal-Wallis test with Dunn’s post-hoc test was used to compare the different grades. Generalized linear mixed-effects models, adjusting for age and grade, with patient-based nesting, were employed to correlate retinal and choriocapillaris perfusion alterations.

Results : A total of 111 eyes (56 patients) were included (median age 63, 64% female). 36 eyes were classified as grade 0 (32%), 10 as grade 1 (9%), 20 as grade 2 (18%), 5 as grade 3 (5%), 17 as grade 4 (15%), 14 as grade 5 (13%), 9 as grade 6 (8%). Eyes with more advanced MacTel grades (5-6) exhibited significant differences in VD and VSD compared with lower-grade eyes (0-2), particularly in temporal and superior sectors. Grade 5 MacTel eyes had significantly greater ICFD% compared to grade 0 across all analyzed areas. Further, ICFD% positively correlated with advanced MacTel grades and negatively correlated with VD and VSD in multiple ETDRS sectors.

Conclusions : This is the first comprehensive SS-OCTA assessment across the recently proposed grades for MacTel classification. The observed differences in retinal and choriocapillaris perfusion suggest distinct characteristics between early and advanced stages of MacTel. Further longitudinal studies are warranted to better characterize the impact of microvascular alterations on the pathogenesis and progression of MacTel.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.