A 3-year-old boy is brought to the clinic by his mother with a complaint of inward deviation of the left eye noticed since 6 months of age. On examination, the child has a left esotropia of 25 prism diopters (PD) with normal visual acuity in both eyes and no refractive error. The cover test confirms the deviation, and the child shows good fixation with either eye. What is the most appropriate next step in management?