Objective: To describe the natural history of optic pathway gliomas (OPGs) in patients with neurofibromatosis type 1 (NF1), and to evaluate the current recommended guidelines for monitoring and follow-up of OPGs in this population.
Design: Retrospective case series.
Participants: Patients with OPGs and NF1 seen in the neurofibromatosis clinic at the Children's Hospital at Westmead in Sydney, Australia.
Methods: Patients with definite NF1 and confirmed OPGs were identified and their medical records searched to obtain data on demographics, details of the OPG diagnosis, and serial ophthalmic examination findings. Patients were stratified into groups according to age and mode of presentation.
Main outcome measures: Visual acuity was recorded for each eye and grouped into mild (Snellen equivalent > or = 6/12), moderate (Snellen equivalent = 6/15-6/60), and severe (Snellen equivalent < 6/60) visual impairment at time of diagnosis, during follow-up, and at the most recent examination.
Results: Data were collected on 54 patients, the majority of whom (78%) were seen from 1990 to 2002, with an average follow-up of 8.6 years. The mean age at the time of OPG diagnosis was 5.2 years, with 32 patients having symptoms or signs at the time of diagnosis. Seventeen patients were diagnosed after the age of 6 years (range, 7-15). Twenty-two patients had tumor progression within 1 year of diagnosis, and a further 6 patients showed progression after 1 year. Most patients' conditions were managed conservatively (68.5%). At follow-up, 17 patients (31.5%) had severe visual impairment (<6/60 Snellen equivalent) in their worse eye, and 16.7% had bilateral moderate/severe visual impairment.
Conclusions: Contrary to some previous reports, our results show that OPGs in patients with NF1 often present in older children and may progress some time after diagnosis. Given the potential for serious visual consequences, these findings indicate a need for regular ophthalmological monitoring of this population for a long duration.