To document the prevalence of refractive errors in patients with neurofibromatosis type 1 (NF1) and type 2 (NF2) and to compare it with that of age- and sex-matched controls.82 patients with NF1, 21 patients with NF2 and 103 age- and sex-matched controls were evaluated in this prospective observational case-control study. Cycloplegic autorefraction and dilated fundus examination were performed. Myopia was defined as the spherical equivalent refraction of at least -0.50 diopters (D), hyperopia as the spherical equivalent refraction of at least 2.0 D and astigmatism as the cylinder of at least 1.0 D. Main outcome measures were refractive error, IQ, years of education, height, weight and body mass index (BMI).The prevalence of myopia was 23.1% in patients with NF1, 23.8% in patients with NF2 and 16.5% in age- and sex-matched controls. These differences were significant (p<0.03, p<0.03), and adjusting for intelligence, education, height, weight and BMI increased the significance of this finding (p<0.001, p<0.001). The prevalences of astigmatism and hyperopia were similar in both groups.A high prevalence of myopia seems to be an additional feature of NF1 and NF2.