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.