Anisometropia in children with neurofibromatosis type 1 and unilateral optic nerve glioma

Background Optic nerve glioma (ONG) occurs in 5% to 25% of individuals with neurofibromatosis type 1 (NF1). Recently an association between this lesion and unilateral myopia was reported in a series of 4 pediatric patients. The purpose of this study was to determine whether unilateral ONG is associated with an increased prevalence of anisometropia. Methods The medical records of children <16 years of age with NF1 disease and unilateral ONG or normal neuroimaging examined at Tel-Aviv Medical Center between April 2008 and July 2013 were retrospectively reviewed to determine the prevalence of anisometropia and anisoastigmatism. Results A total of 75 children with NF1 disease were included. Of these, 25 (11 boys) had a unilateral ONG (mean age, 7.2 years; range, 2-16 years) and 50 (29 boys) had normal neuroimaging (mean age, 8.3 years; range, 1-15 years). The mean refraction (spherical equivalent) of eyes with ONG did not differ significantly from that of the contralateral eyes (0.74 ± 1.41 D vs 0.71 ± 1.19 D; P = 0.935; 95% CI, -0.710 to 0.770); moreover, there was a high correlation between the refraction of eyes with ONG and contralateral eyes (r = 0.946, P < 0.001). The prevalence of anisometropia in children with ONG and in NF1 children with no orbital pathology did not differ significantly (8% vs 16%; P = 0.480), and the prevalence of anisoastigmatism was also similar in both groups (4% vs 14%, P = 0.255). Conclusions ONG in children with NF1 is not associated with increased prevalence of anisometropia.