Outer Retina Segmentation Slab Vascularization in Macular Telangiectasia Type 2: Multimodal Imaging Characterization and Development of an ORSS-V Scoring System

PURPOSE: To characterize outer retina segmentation slab (ORSS) vascularization in Type 2 macular telangiectasia (MacTel) using multimodal imaging and to develop a regression-derived scoring system for differentiating true neovascularization from non-neovascular vascularization. METHODS: In this retrospective study, 336 eyes of 174 patients with Type 2 MacTel were screened, of which 150 eyes (80 patients) with analysable optical coherence tomography angiography (OCTA) were included. ORSS vascularization was identified in 92 eyes (61.3%). Multimodal imaging features from optical coherence tomography (OCT), fundus fluorescein angiography (FFA), and OCTA were analyzed. Multivariable logistic regression was performed to identify predictors of neovascularization (subretinal neovascular membrane; SRNVM), and a weighted composite score (ORSS-V score) was developed and validated using receiver operating characteristic (ROC) analysis. RESULTS: Among eyes with ORSS vascularization, 33 (35.9%) demonstrated SRNVM, while 59 (64.1%) did not. Eyes with SRNVM were older (mean: 63.4 years) and had worse visual acuity [Mean logMAR = 0.62; 20/83] (p ≤ 0.001). Key differentiating features included subretinal and intraretinal fluid on OCT, focal intense leakage on FFA, complex OCTA vascular network, and deep capillary plexus vascular bunching (all p < 0.001). The ORSS-V score demonstrated excellent discriminative ability (area under ROC = 0.91). At a cut-off ≥6, sensitivity was 88% and specificity 86%. CONCLUSION: ORSS vascularization is common in MacTel and often non-neovascular. A multimodal imaging approach, supported by the ORSS-V scoring system, enables reliable differentiation between invasive vascularization and true neovascularization, improving diagnostic accuracy and guiding clinical management.