The result of surgery for infantile esotropia (IE) can be described by the following outcome parameters: (1) the binocular vision conserved or regained by early surgery, (2) the postoperative angle of strabismus and the long-term stability of alignment, and (3) the number of operations needed to reach these goals or the chance of spontaneous reduction of the strabismus into a microstrabismus without surgery. To judge the best age for surgery in a specific child with IE, the expected outcome of surgery should be estimated according to these parameters.
There have been no studies with prospectively assigned early- and late-surgery groups and an evaluation according to intention-to-treat, other than the Early vs. Late Infantile Strabismus Surgery Study (ELISSS). The primary outcome of that study was that 13.5% of those operated at approximately 20 months of age against 3.9% (P = 0.001) of those operated at approximately 49 months recognized the Titmus Housefly at the age of 6 years; there was no difference in stereop-sis beyond Titmus Housefly.
Reoperation rates were 28.7% in the early and 24.6% in the late group. 8.2% of the children scheduled for early surgery and 20.1% of the children scheduled for late surgery had not been operated at the age of 6 years; most developed a microstrabismus. Esotropia less than 14° at baseline at approximately 11 months of age had not been operated at the age of 6 years in 35% of the cases. Hypermetropia around spher. + 4 increased the likelihood of regression without surgery, underscoring the need of full refractive correction.
Findings of substantially finer stereopsis after very early surgery await confirmation in a randomized controlled trial.