Effects of strabismus surgery on choroidal blood flow: a systematic review and meta-analysis

BACKGROUND: Strabismus surgery may affect choroidal circulation, with potential implications for outer retinal nourishment and visual function. We conducted a systematic review and meta-analysis to quantify postoperative changes in subfoveal choroidal thickness and vascularity parameters following strabismus surgery. METHODS: A systematic search was conducted in PubMed, Scopus, and Web of Science. After two-stage title/abstract and full-text screening, eligible observational studies reporting pre- and postoperative optical coherence tomography (OCT) or OCT angiography (OCTA) choroidal measures were included. Random-effects meta-analyses estimated pooled mean differences for subfoveal choroidal thickness (SFCT), choroidal vascularity index (CVI), foveal choriocapillaris vessel density (VD), and choriocapillaris flow. Subgroup analyses, meta-regression, quality assessment using the Risk Of Bias In Non-randomized Studies of Interventions (ROBINS-I) tool, and evaluation of publication bias were performed. RESULTS: Eighteen studies met the inclusion criteria. Pooled analysis of 22 groups (14 studies) showed no significant overall change in SFCT after strabismus surgery (mean difference − 1.13 μm; 95% CI − 6.93 to 4.67; p = 0.70; I2 = 52.1%). CVI (seven groups, five studies) showed no significant change (pooled mean change 0.001; 95% CI − 0.006 to 0.008; p = 0.70; I2 = 0.04%). Foveal choriocapillaris VD and flow showed no significant pooled changes, though choriocapillaris VD exhibited substantial heterogeneity (I2 = 87.9%). Meta-regression detected no associations with follow-up duration, surgical procedure, or number of muscles. No clear publication bias was observed. CONCLUSION: Current observational evidence suggests no consistent alterations in SFCT, CVI, or choriocapillaris vascularity metrics during the intermediate postoperative period following strabismus surgeries.