Comparison of the Effects of Wearing Overminus Spectacles versus Patch Therapy in 3- to 8-Year-Old Children with Intermittent Exotropia: A Randomized Controlled Trial

Background and Objective: Intermittent exotropia is the most common form of exotropia in children. Non-surgical treatments include refractive error correction, occasional patching of the normal eye in young children, prism therapy, and orthoptic exercises. This study aimed to compare the effects of wearing overminus spectacles versus patch therapy in 3- to 8-year-old children with intermittent exotropia. Methods: This clinical trial was conducted on 30 children (9 boys and 21 girls) with intermittent exotropia aged 3 to 8 years with no previous treatment history referring to the strabismus clinic of Khatam-al-Anbia Hospital in Mashhad. Patients were randomly assigned to two groups: Patch therapy (n=20) and overminus (n=10). In the patch therapy group, the patient’s healthy eye was patched for 2 to 4 hours a day for 6 months. Overminus spectacles were selected based on cycloplegic refraction between 2 and 4 diopters. Astigmatism was fully prescribed. Patient follow-up time was 3 months and then 6 months. Finally, data, including the size of the deviation and the degree of deviation control, were collected and analyzed. Results: The median spherical error of patients before intervention in the overminus group was +1 diopter in the right eye and +0.75 diopter in the left eye, and in the patch therapy group, +0.75 diopter in both the right and left eyes. Six months after the intervention, the median spherical error in the overminus group was +0.62 diopters in both the right and left eyes, and in the patch therapy group, +0.75 diopters and +0.62 diopters in the right and left eyes, respectively. No significant statistical difference was found between the study groups. The median deviation size of patients in the overminus group before intervention was +25 prism in distance vision and +25 prism in near vision, and 6 months after intervention, it was +22.5 prism in distance vision and +20 prism in near vision. Also, the median deviation size of patients in the patch therapy group before intervention was +25 prism in distance vision and +25 prism in near vision, and 6 months after intervention, it was +25 prism in distance vision and +25 prism in near vision. No significant statistical difference was found between the study groups. The median deviation control based on the Newcastle Scale Score (NSS) of patients before intervention was 3.5 in the overminus group and 4 in the patch therapy group, which was 1.5 in the overminus group and 3 in the patch therapy group 6 months after the intervention. Although there was a greater improvement in control based on the NSS in the overminus group compared to the patch therapy group. Conclusion: Both overminus and patch therapy are effective in treating patients with intermittent exotropia. In patients using the overminus method, deviation control is higher compared to the patch therapy method.