Anterior segment blood supply after horizontal rectus muscle surgery using optical coherence tomography angiography

To evaluate the change in anterior segment blood supply after horizontal rectus muscle surgery using anterior segment optical coherence tomography angiography (AS-OCTA) and to explore the influencing factors.

This prospective, longitudinal study included patients undergoing horizontal rectus muscle surgery. AS-OCTA images of the iris and episcleral-limbal plexus (ELP) were captured preoperatively and at 1 day, 1 week, 1 month and 3 months. Vessel densities were calculated and compared among different groups. Risk factors were explored using stepwise multivariate linear regression.

Sixty patients were enrolled and underwent surgery, 24 for lateral rectus muscle (LR), 11 for medial rectus muscle (MR), and 25 for unilateral medial and lateral rectus muscles (R&R). Vessel densities in the LR group recovered to the preoperative level at postoperative 1 week (ELP: P = 0.052; Iris: P = 0.065), whereas not until 1 month postoperatively in the MR (ELP: P = 0.084; Iris: P = 0.383) and R&R groups (ELP nasal side: P = 0.454; ELP temporal side: P = 0.929; Iris: P = 0.563). The MR and R&R groups experienced greater decreases in iris vessel density (MR: 1.44 ± 1.43 %, P = 0.021; R&R: 1.12 ± 1.42 %, P = 0.021) than the LR group (0.26 ± 0.62 %). Older age (P < 0.001), increased BMI (P = 0.014), and smoking history (P = 0.008) were strong indicators for poorer iris recovery at postoperative 1 month.

Horizontal rectus muscle surgery induced decreased anterior segment blood supply, which averagely recovered within 1 month. Patients predicted at high risk including those of older age, increased BMI, or a smoking history, may benefit from regular monitoring with AS-OCTA.