Thesis (Ph.D.) - Cairo University - Faculty of Medicine - Department of Ophthalmology

Purpose: to compare the motor and sensory outcomes of early surgery ({u2264}5 years of age) versus late surgery ({u2265} 7 years of age) for intermittent exotropia. Design: a prospective observational study Methods: a total of 136 patients with intermittent exotropia was divided into two groups according to the age at surgery. In the late surgery group, bilateral lateral rectus recession was performed according to standard tables. In the earlier surgery group, the amount of lateral rectus recession was reduced by 0.5 mm. Motor alignment and sensory functions were followed up for six months.Complete success was defined as esophoria or intermittent esotropia < 5 PD to exophoria/tropia <8 PD for both distance and near with spectacles at 6 months. The study was registered in Clinical trial.gov (NCT04307160). Results: The mean age at surgery was 3.45 ± 1.00 years and 11.46 ± 5.29 years in the early and late surgery groups respectively. Success rate was 84% in the early surgery group and 68% in the late surgery group. The higher success rate in the early group was statistically significant (P =0.033). Overcorrection occurred in 2 patients in the early group (3%) and 5 patients (8%) in the late group. There was no statistically significant change in the postoperative stereo-acuity after surgery. Conclusion: Surgery at younger age was associated with a higher success rate at 6 months. The risk of overcorrection can be minimized with a reduced surgical dose. Longer follow up is needed to test the stability of the results

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