Comparison Of Different Surgically Treating Convergence Insufficiency-type Intermittent Exotropia

Objective: To compare the efficacy of improved unilateral lateral rectus recessionmedial rectus resection with unilateral lateral rectus recession for patients with convergence insufficient-type intermittent exotropia.Methods: A total of 55 patients with convergence insufficient-type intermittent exotropia(CI-IXT)were collected from the group of Strabismus and Pediatric Ophthalmology of the First Affiliated Hospital of Fujian Medical University from September 2017 to September 2019.Depending on the surgical procedure,all patients were divided into two groups: 23 cases in the unilateral lateral rectus recession group(ULR),and 32 cases in the improved unilateral lateral rectus recession-medial rectus resection group(RR).All patients underwent routine eye examination and refractive correction.Titmus stereogram and Bagolini glasses were used to evaluate the binocular vision of the patients.The patients were examined with prism and alternative cover test after covering one eye for at least half an hour to measure the near and distance prism diopter of exotropia.And design the surgical procedure based on the maximum prism diopter measured at distance and near vision.In ULR group,the surgical volume of the lateral rectus recession was based on the distance prism diopter of exotropia;in RR group,the lateral rectus recession was based on the half of the distance prism diopter of exotropia,and the medial rectus resection is 0.5 to 1.0mm larger than the amount of the lateral rectus recession.All patients were followed up at 3 months and 6 months after surgery.The surgical success rate and the recurrence rate at each follow-up time point,the exotropia changes before and after surgery,and the differences of the strabismus in near and distance were evaluated.Data analysis was performed using SPSS 23.0 for statistical analysis.P value <0.05 was considered statistically significant.Results: The surgical success rate at 3 months after operation was 73.91% in the ULR group and 71.87% in the RR group,the difference in success rates was not statistically significant(P = 0.867).at 6 months after surgery,the success rate of the RR group was 75.00%,which was significantly higher than that was 39.13% of the ULR group(P = 0.007).At 3 months after surgery,the distance(+ 0.13 ± 4.21PD)and near(-3.91 ± 4.86PD)strabismus of the RR group was significantly overcorrected compared with the distance(-2.83 ± 4.26PD)and near(-7.83 ± 4.37PD)prism diopter of the ULR group(P = 0.014 and P = 0.003).At 6 months after surgery,the patients in both groups showed significant regression phenomenon,and distant and near vision strabismus regressed simultaneously.There was no significant difference in the distance and near strabismus regression of the two groups from 3months to 6 months after surgery(P = 0.954 and P = 0.212).compared with preoperative situation(16.83 ± 3.21 and 18.50 ± 3.65),the distance-near differences in the ULR group(5.96 ± 3.54PD)and RR group(4.22 ± 2.54PD)at 6 months postoperation were significantly reduced(P = 0.000 and P = 0.000).There was no significance statistical change in the distance-near differences in the two groups from3 months to 6 months after surgery(P = 0.339),and also was no significant difference between the two groups at 3 months after surgery(P = 0.143).At 6 months after surgery,patients in the RR group show distance-near differences slightly less than that in the ULR group(P = 0.051).At 6 months postoperatively,only one patient in the ULR group expressed lateral incomitance.The number of patients in the two groups with normal stereopsis,normal distance and near Bagolini glasses at 6 months of postoperation was significantly higher than preoperation.There was no significant statistically difference between the two groups in that three binocular vision tests before and after surgery(P = 0.612,P = 0.789,and P = 0.811).Conclusions: At the 6-month follow-up,the success rate of improved unilateral lateral rectus recession-medial rectus resection was higher than that of unilateral lateral rectus recession for patients with convergence insufficient-type intermittent exotropia.Both improved unilateral lateral rectus recession-medial rectus resection and unilateral lateral rectus recession can effectively reduce the distance and near prism diopter of exotropia,and the distance-near differences,in patients with convergence insufficient-type intermittent exotropia.And both of the two surgical procedure can significantly improve binocular vision in this type of patients.