Vision Abnormalities in Pediatric Brain Tumors Predictable With Structural Imaging

Vision abnormalities in pediatric brain tumors can be determined using optical coherence tomography (OCT) evaluations of the mean circumpapillary retinal nerve fiber layer (RNFL), and macular ganglion cell layer–inner plexiform layer (GCL-IPL) thicknesses, according to a report published in Acta Ophthalmologica.

Visual impairment is a potential risk for survivors of pediatric brain tumors, yet detection of early vision loss may be more difficult because the usual tests for acuity and visual fields (VF) are subject to patients’ young age, neurologic condition, fear, or fatigue. Researchers  assessed whether retinal layer thickness can indicate visual function.

This cross-sectional analysis included 115 patients (median patient age, 10.6 years [range, 0.2 to 17.8 years]; 58.3% boys) with newly diagnosed brain tumors between May 2019 and August 2021. Regions of tumor locations comprised infratentorial (50.4%), supratentorial midline (28.7%), and the supratentorial cerebral hemispheres (20.9%). Ophthalmic examinations took place in 4 weeks or fewer from diagnosis, and included tabletop or hand-held OCT. Reliable measurements of RNFL thickness were obtained in 80.0%, and GCL-IPL thickness for 73.0%. 

The researchers were able to show an 82.6% negative predictive value (NPV) for mean circumpapillary RNFL thickness, along with 82.2% NPV of mean macular GCL-IPL thickness, indicating a high capacity for predicting vision abnormalities in pediatric brain tumors. However, the positive predictive value (PPV) for RNFL depth was 33.0% and for GCL-IPL thickness it was 57.1%, the researchers report. Thus, the ability to distinguish visual function is moderate, according to the report.

Average RNFL thickness showed 74.5% sensitivity and 44.5% specificity to discern vision abnormalities, and mean GCL-IPL thickness yielded 41.7% sensitivity and 82.9% specificity. A subgroup analysis for children with optic pathway glioma (OPG) revealed median RNFL thickness at 105 µm (82 to 329 µm) in patients with normal function, and 82 µm (59 to 145 µm) for those with abnormal acuity or visual fields, or both. Regarding craniopharyngioma and normal visual function, median RNFL thickness was 104 µm (88 to 258 µm), compared with patients with vision abnormalities and pediatric brain tumors, 110.5 µm (83 to 282 µm).

Investigators do not yet advise objective measurements to replace complete assessment by a neuro-ophthalmologist for vision abnormalities in pediatric brain tumors; however, “the relatively high NPVs for the average circumpapillary RNFL thickness and average macular GCL-IPL thickness signify that children with normal thickness measurements at brain tumor diagnosis have a relative high certainty of a normal visual function and as such may be helpful in children who are not cooperative with traditional VA and/or VF examination,” the study explains. 

Prior studies of diagnostic effectiveness in OPG reported higher NPVs and PPVs for RNFL thickness than the current subtype analysis, possibly due to cohort differences, fewer patients with OPG involving abnormal visual function, or varying criteria for abnormal RNFL and GCL-IPL thicknesses. In research on craniopharyngioma, children with vision loss showed RNFL thinning, but results were not directed toward a diagnostic purpose.

A limitation of this study is that many pediatric brain tumor types were included, some of which may produce more papilledema — and 2 subtypes analyzed comprised small groups. Additionally, 3 OCT instruments were used, along with a dedicated algorithm for each. Two of the devices’ software do not segment GCL-IPL thickness, affecting 8.7% of participants.

This article originally appeared on Ophthalmology Advisor