Sensory results after lateral rectus muscle recession for intermittent exotropia operated before two years of age

IntroductionEarly surgical treatment of early-onset intermittent exotropia is controversial. The condition does not always progress, and postoperative esotropia can produce adverse consequences, such as suppression, amblyopia, and loss of binocular vision, particularly stereopsis. It is not known whether surgery before age two years affects the sensory outcome.MethodsUsing a noncomparative (nonrandomized, uncontrolled) interventional case series, we reviewed the medical records during a 14-year period of 24 patients with intermittent exotropia with onset before age 1 year who also received bilateral lateral rectus muscle recessions before two years of age. Twelve patients were identified who received follow-up examinations at ages ≥4 years, when testing with Worth 4-Dot and Titmus stereo circles would likely be reliable.ResultsMean age of the patients at last follow-up examination was 87 months. Stereoacuity was measured at 40 arcsec in 2 patients, 100 arcsec in 3 patients, 140-400 arcsec in 2 patients, and none in 5 patients. Among the 5 patients without demonstrated stereopsis, 1 had a history and clinical course consistent with congenital exotropia, and 1 had a nonstrabismic explanation for poor stereopsis. Overall, 7 patients (58%) ultimately obtained favorable motor alignment, defined as a phoria or intermittent tropia <10Δ at distance and near. No patient required treatment for amblyopia.ConclusionsEarly-onset intermittent exotropia usually responds well to surgical treatment, and high-grade stereopsis can be achieved in some cases. More than one clinical entity presenting as intermittent exotropia in infancy probably exists.