The prevalence of anisometropia aniso-astigmatism and amblyopia in neurofibromatosis type 1

PURPOSE: The purpose of this study was to document the prevalence of anisometropia, anisoastigmatism, and anisometropic amblyopia in patients with neurofibromatosis-1 (NF1) and to compare it with that in age- and sex-matched controls. METHODS: Fifty patients with NF1 and 150 age- and sex-matched controls were examined in this study. Cycloplegic autorefraction was attempted on all patients <16 years old and without cycloplegia on patients >16 years old. Anisometropia was defined as absolute interocular difference of spherical equivalent more than or equal to 1 D. Aniso-astigmatism was defined as interocular difference of refractive astigmatism of more than or equal to 1 D. Amblyopia was defined as two-line decrease in Snellen acuity between the two eyes. RESULTS: The overall prevalence of anisometropia, aniso-astigmatism, and amblyopia in patients with NF1 was 16%, 20%, and 10%, respectively, and they were all significantly higher than in the controls. The amblyopia was either moderate or severe in nature and all affected patients had significant astigmatism (>2.5 D) in the amblyopic eye. CONCLUSIONS: NF1 is a risk factor for anisometropia, aniso-astigmatism, and aniso-astigmatic amblyopia and screening patients with NF1 for refractive errors before age 3 will help to detect patients at risk of amblyopia and give them proper treatment.