Effects of slanted bilateral lateral recession vs conventional bilateral lateral recession on convergence insufficiency intermittent exotropia: a prospective study

AIM: To observe the surgical effects of slanted bilateral lateral recession (S-BLR) versus conventional bilateral lateral recession (C-BLR) in convergence insufficiency intermittent exotropia (CI-IXT). METHODS: Using a randomized, double-blind, prospective design, 22 patients with CI-IXT who were admitted to Renmin Hospital of Wuhan University from July 2019 to December 2020 were included. Patients were randomly divided into either S-BLR or C-BLR group for their subsequent strabismus surgery. All patients were followed up for 12mo. Near deviation, distant deviation, and near-distance difference (NDD) were measured in all patients. RESULTS: Twelve months after surgery, NDD improvement was 10 (8, 13) prismatic degrees (PD) in S-BLR group and 3 (1, 6) PD in C-BLR group (P=0.011). The near deviation of S-BLR group was 0 (-2, 2) PD, while that of C-BLR group was -4 (-6, -3) PD (P=0.005). Before and after surgery, the difference in the distant deviation between the two groups was not statistically significant. There was no statistically significant difference in near stereopsis between the two groups (P=0.380) at 12mo. The success rate at 12mo after operation was 90.91% and 72.73% in the two groups (P=0.280). CONCLUSION: CI-IXT patients treated with S-BLR have better surgical outcomes than those treated with C-BLR, which indicates S-BLR is a safe and effective operation pattern.