Stereopsis following delayed strabismus surgery in early-onset strabismus

PURPOSE: Improved stereoacuity following delayed strabismus surgery is associated with long-term alignment of eyes and reduced severity of amblyopia. The objective of this study is to evaluate stereopsis following delayed strabismus surgery in early-onset strabismus. METHODS: It is a hospital-based prospective, nonrandomized, interventional case study. Thirty patients with early-onset strabismus (before 3 years of age), presenting after 6 years of age were included. History taking and full orthoptic workup was done. Stereopsis was tested with Titmus Fly Chart test. The patients were treated surgically to correct strabismus and were followed up for 3 months. Quantitative parameters were compared between preoperative and postoperative follow-up at 3 months using McNemar test, Chi-square test, and independent t-test. RESULTS: Of the 21 patients who had gross stereopsis preoperatively, nine of them (42.86%) attained fine stereopsis at 3 months postoperatively (P = 0.003, McNemar test). Ten (33.33%) of 30 patients had amblyopia and three out of 30 patients (10%) had preoperative “nil” stereopsis. Of the patients who showed improvement (16 of 30 patients – 53.33%), most of the improvement was observed in (a) exodeviations (56.25%, n = 9), (b) earlier age of presentation-before 10 years of age (47.36%, n = 9). CONCLUSION: The benefits of surgical correction of early-onset strabismus include improvement in stereopsis. Therefore, even in an early-onset squint with a delayed presentation rehabilitation of stereopsis should be the goal of treatment.