Changes in iris microvasculature after horizontal strabismus surgery: anterior segment OCTA combined with synoptophore-based functional assessment.

PURPOSE: To characterize short-term dynamic changes in iris microcirculation after horizontal strabismus surgery and to explore their associations with postoperative binocular visual function.

METHODS

In this prospective self-controlled study, 71 eyes from 56 patients who underwent horizontal rectus muscle surgery at Shanxi Provincial Eye Hospital between June and October 2025 were enrolled (one-muscle group: 17 eyes; two-muscle group: 54 eyes). Anterior segment OCT angiography was performed 1 day before surgery and at 1 day, 2 weeks, and 6 weeks postoperatively to quantify iris vessel density (VD), iris vessel skeleton density (VSD), and iris perfusion area (PA). Synoptophore testing was used to assess simultaneous perception/fusion grades, and near stereopsis was assessed with the Titmus test. Linear mixed-effects models were applied to examine associations between functional variables and OCTA metrics.

RESULTS

Iris VD and VSD exhibited reversible short-term fluctuations after surgery, with larger changes in the two-muscle group, whereas PA remained relatively stable. From postoperative week 2 onward, simultaneous perception, fusion, and stereopsis generally improved. Mixed-effects modeling indicated negative associations of the number of operated muscles with VD and VSD, and positive associations of simultaneous perception/fusion with VSD. No significant correlation was found between Titmus stereopsis and OCTA parameters.

CONCLUSIONS

Horizontal strabismus surgery is associated with subclinical, reversible short-term alterations in iris microcirculation. The association between iris OCTA parameters, particularly VSD, and synoptophore grade I/II function suggests that these metrics may provide complementary information during postoperative functional assessment; however, binocular recovery remains influenced by ocular alignment and other sensory factors.