Impact of Strabismus Surgery on Anterior Segment Hemodynamics: An SS AS-OCTA-Based Study

Purpose: The purpose of this study was to evaluate anterior segment (AS) hemodynamic changes after horizontal rectus muscle surgery using swept-source AS optical coherence tomography angiography (SS AS-OCTA). Methods: This prospective observational study included 99 patients undergoing unilateral horizontal rectus muscle surgery, classified into unilateral recession (UR) and recession–resection (RR) groups. Iris and conjunctival perfusion area (PA), microvascular density (MVD), and vascular density (VD) were measured preoperatively and at postoperative day 1, week 1, and month 1. Results: Iris changes were mild and localized after UR, whereas RR induced broader and transient increases in iris VD and other hemodynamic parameters, most evident at 1 day and 1 week and approaching baseline by 1 month. Conjunctival changes were more pronounced, particularly in operated quadrants, where PA and VD increased early after surgery. Non-operated quadrants also showed increased vascular parameters, suggesting possible redistribution of detectable vascular signals. Higher preoperative iris VD was associated with smaller postoperative changes. No clinically apparent anterior segment ischemia (ASI) was observed during follow-up. Conclusions: Horizontal rectus muscle surgery induces distinct but largely transient AS hemodynamic alterations, with greater changes after RR than UR. SS AS-OCTA enables noninvasive quantitative assessment of perioperative changes in AS vascular signals. Translational Relevance: SS AS-OCTA may be most useful for studying reoperations, multiple-muscle or transposition procedures, and patients at increased risk of AS ischemia.