Background: Optic pathway glioma (OPG) is a classic complication of neurofibromatosis type 1 (NF1) and can impair visual function in children with this condition. The objective of this study is to describe clinical, paraclinical and prognostic characteristics of OPG associated with NF1.

Methods: In this retrospective observational study of children followed for OPG associated with NF1 in a University Hospital, we analyzed the ophthalmological examination, brain and orbital imaging, management and the presence of associated endocrinopathy.

Results: We examined 114 children with NF1, of which 26 (22.81%) presented with OPG. Mean ages at diagnosis of NF1 and OPG were 3.83 years and 6.23 years, respectively. Mean visual acuity was 20/24.4 for the worse eye and 20/23.1 for the better eye. The RNFL (retinal nerve fiber layer) was thinner in subjects than in age-matched controls (p <0.0001). Retrochiasmal location of the OPG (DodgeC) was associated with lower binocular visual acuity than other locations and <20/32 (p=0.028); 28.03% of OPG (5 girls and 1 boy) were treated with chemotherapy, and the others were monitored; 19.23% had an associated endocrinopathy.

Conclusions: OPG complicates 22.81% of NF1 cases in our series. Our study shows that retrochiasmal location of the glioma and female sex are poor prognostic factors. It also highlights the important role of OCT, since a decrease in RNFL is statistically associated with the presence of an OPG.