Macular microcirculation after extraocular muscle surgery: A comparative OCTA study of inferior oblique versus horizontal rectus procedures

Purpose To compare macular microvascular changes after horizontal rectus and inferior oblique (IO) muscle surgeries using swept-source optical coherence tomography angiography (OCTA) and to assess the distinct vascular effects of each surgical approach. Methods Eighty-two pediatric and adolescent patients with concomitant strabismus underwent unilateral extraocular muscle surgery. Group 1 (n = 43) received horizontal rectus muscle surgery; Group 2 (n = 39) underwent IO weakening surgery. The fellow unoperated eye served as a control. Macular microvasculature was evaluated before surgery, at 1 week, and 1 month postoperatively using a swept-source OCTA system. Vessel density (VD) of the superficial capillary plexus (SCP), deep capillary plexus (DCP), and choriocapillaris (CC), as well as the foveal avascular zone area (FAZ), was quantitatively analyzed. Results In the horizontal rectus group, SCP VD significantly increased in the 1st week compared to baseline (49.97% ± 2.41% vs. 51.16% ± 3.23%, p = 0.037) and returned to baseline values in the 1st month. A transient increase in CC VD was also observed at the 1st week (p = 0.006). No significant changes occurred in the DCP and FAZ. In the IO group, no significant changes were found in the SCP, DCP, or FAZ. However, a mild, transient increase in CC VD was observed at the 1st week (p = 0.001), which returned to baseline by the 1st month. Conclusion Horizontal rectus muscle surgery induces significant but transient changes in macular retinal and choroidal perfusion. In contrast, IO muscle surgery induces only localized and temporary choroidal alterations. OCTA may therefore serve as a valuable noninvasive tool for postoperative monitoring of vascular alterations in strabismus surgery.