Subfoveal and Peripapillary Choroidal Assessment in Multiple Sclerosis with Unilateral Optic Neuritis

To investigate regional choroidal and retinal alterations in multiple sclerosis (MS) by simultaneously evaluating subfoveal and peripapillary choroidal vascularity index (CVI) together with peripapillary retinal nerve fiber layer (RNFL) thickness in unilateral optic neuritis (ON) patients.

This prospective study included 31 MS patients with unilateral ON within the previous 12 months (clinically stable for ≥3 months), and 73 age- and sex-matched healthy controls. Enhanced-depth imaging optical coherence tomography (EDI-OCT) provided subfoveal and peripapillary scans. CVI was quantified using a standardized Niblack-based ImageJ binarization protocol, and peripapillary RNFL thickness was measured on optic disk-centered circular scans. Two masked observers measured CVI, and interobserver intraclass correlation coefficients (ICC) were calculated. Group comparisons were performed among ON-affected (ON+), unaffected fellow (ON-), and control eyes using age- and sex-adjusted generalized estimating equations (GEE).

Subfoveal CVI differed among groups (p < 0.001) and was higher in both ON+ and ON- eyes than controls (p < 0.001 for both), with no difference between MS subgroups (p = 1.000). Peripapillary CVI did not differ in any quadrant (all p > 0.05). Global RNFL thickness was reduced in both ON+ and ON- eyes compared with controls (p < 0.001). Temporal RNFL was thinner in both MS subgroups than controls (p < 0.001 for both). Superior, inferior, and nasal RNFL values were lowest in ON+ eyes (p ≤ 0.001 vs ON-; p < 0.001 vs controls), while ON- and controls did not differ in the nasal quadrant (p = 0.168). Interobserver reproducibility was excellent (ICC 0.90-0.94).

Subfoveal CVI was higher within the standardized 3-12-month post-ON period, whereas peripapillary CVI remained comparable across groups despite marked RNFL thinning. Combined assessment of CVI and RNFL may provide complementary structural information regarding neurovascular changes in MS.