Refractive errors and strabismus in Asian patients with Down syndrome

Purpose The purpose of this study was to investigate the prevalence and patterns of refractive errors and strabismus in Asian patients with Down syndrome, as they relate to age. Methods A total of 261 Korean patients with Down syndrome were examined between March 1999 and May 2007. Eighty-nine patients were excluded from the study. The remaining 172 patients were divided into four age groups ( < 3 years, 3- < 6 years, 6- < 9 years, and ≥9 years). Full ophthalmologic examinations and strabismus assessments were performed. Refractive errors were defined as follows: myopia ≥―1.00 D, hyperopia ≥ + 1.00 D, astigmatism ≥ ± 1.00 D, and anisometropia as a refractive difference between the two eyes ≥1.00 D. Results Hyperopia (46.5%) was slightly more common than myopia (40.1%). The prevalence of myopia increased with age, whereas that of hyperopia decreased. Astigmatism was found in 66.8% of patients, and astigmatism ≥2 D was found in 16.8% of patients. Anisometropia was identified in 29.7% of patients, and the incidence of anisometropia correlated significantly with age as well as with astigmatism. Esotropia (22.1%) was twice as common as exotropia (10.5%). The prevalence of esotropia increased with age, but that of exotropia decreased. Fifty patients were found to have nystagmus (29.1%). Conclusions In Asian patients with Down syndrome, esotropia was more common than exotropia and hyperopia was more common than myopia. The prevalence of exotropia and astigmatism was much higher in this study than has been previously reported.