Effects of endoscopic transnasal orbital decompression on anterior segment ocular blood flow and clinical outcome in thyroid-associated ophthalmopathy: a retrospective study.

BACKGROUND: Thyroid-associated ophthalmopathy (TAO) is characterized by orbital inflammation and elevated intraorbital pressure, which may compromise anterior segment microcirculation. While endoscopic transnasal orbital decompression (ETOD) effectively alleviates proptosis and improves vision, its effect on microcirculation remains underexplored. OBJECTIVE: This study aimed to evaluate the effect of ETOD on anterior segment microcirculation in TAO using SS-OCTA and to correlate these changes with clinical outcome. METHODS: This retrospective study included 45 TAO patients undergoing ETOD and 45 matched healthy controls. SS-OCTA measures (superficial, deep, and small vessel density; blood flow area) and clinical measures (exophthalmos, intraocular pressure, best-corrected visual acuity) were assessed preoperatively and 3 months postoperatively. RESULTS: Preoperatively, SVD was significantly higher in TAO patients than in healthy controls (50.63 ± 1.98% vs. 48.53 ± 2.78%, P < 0.001), whereas DVD showed no significant difference (47.93 ± 1.59% vs. 47.30 ± 2.57%, P = 0.169). In contrast, BFA was significantly lower (2.07 ± 0.31 vs. 2.49 ± 0.27 mm2, P < 0.001), whereas SmiVD showed no significant difference (P = 0.939). Three months after ETOD, SVD and DVD decreased significantly (temporal quadrant SVD: from 51.53 ± 2.26% to 43.37 ± 1.78%, -15.8%, P < 0.001; temporal DVD: from 47.81 ± 2.49% to 38.66 ± 2.70%, -19.1%, P < 0.001), whereas BFA increased significantly (temporal BFA: from 2.08 ± 0.49 mm2 to 2.34 ± 0.45 mm2, +12.5%, P < 0.001). SmiVD remained unchanged (P > 0.05). BCVA showed no significant change (LogMAR 0.05 ± 0.06 to 0.04 ± 0.07, P = 0.290). Exophthalmos reduction showed a significant positive correlation with SVD reduction (r = 0.346, P = 0.020), and postoperative IOP was not significantly correlated with postoperative SmiVD (r = 0.024, P = 0.875). CONCLUSIONS: ETOD effectively reduced exophthalmos and IOP and restored anterior segment hemodynamics by decreasing pathologically elevated vessel densities toward normal levels. SS-OCTA provides a valuable noninvasive tool for monitoring microcirculatory changes after orbital decompression in TAO.