Methods
This is a retrospective chart review of patients treated for OPG at a tertiary care pediatric health center from 7/1/2013 to 9/1/2021. The study was approved by an institutional review board. Inclusion criteria included diagnosis of sporadic or NF1-associated OPG, defined as low-grade glial tumor involving the optic nerves, chiasm, post-chiasmal tracts, or optic radiations; age less than 18 years at treatment; receipt of BBT for OPG; and documentation of visual function before and after treatment. Exclusion criteria included comorbid malignant tumor; receipt of chemotherapy for indications other than OPG; and radiation therapy prior to BBT.
VA and VF information were abstracted from clinical ophthalmology notes for baseline and post-treatment timepoints. The baseline timepoint was defined as 3 months before initiation of BBT. The post-treatment timepoint was defined as either the last documented ophthalmology examination or, in the event of disease progression, the last documented ophthalmology exam prior to initiation of a subsequent therapy. Clinically significant change in VA was defined as a change from baseline of 0.2 logMAR11. VF data was obtained from formal perimetric techniques including Goldmann and Humphrey perimetry. Clinical evaluations with confrontation alone (without formal perimetry) were excluded. Clinically significant change in VF was defined as change between (1) full field and any field loss, (2) quadrantic and hemifield loss, or (3) generalized constriction or expansion of VF4. Radiographic response was assessed from clinical notes and radiology reports at baseline and at the end of BBT.