# Grating visual acuity impairment assessed by sweep visually evoked potentials in children with optic pathway tumors unable to perform optotype acuity tests

## TL;DR

This study uses a special test to measure vision loss in children with brain tumors near the optic pathway who cannot take regular vision tests.

## Contribution

The study introduces the use of sweep visually evoked potentials to assess grating visual acuity in children with optic pathway tumors.

## Key findings

- Grating visual acuity deficits were classified as mild, moderate, or severe in 25 children with optic pathway tumors.
- Interocular differences in visual acuity were found in 64% of children.
- Visual impairment levels correlated with ophthalmological and neuroimaging findings.

## Abstract

To determine visual impairment due to optic pathway tumors in children unable
to perform recognition acuity tests.

Grating visual acuity scores, in logMAR, were obtained by sweep visually
evoked potentials (SVEP) in children with optic pathway tumors. The
binocular grating visual acuity deficit was calculated by comparison with
age-based norms and then assigned to categories of visual impairment as mild
(from 0.10 to 0.39 logMAR), moderate (from 0.40 to 0.79 logMAR), or severe
(≥0.80 logMAR). Interocular differences were calculated by
subtraction and considered increased if >0.10 logMAR.

The participants were 25 children (13 boys; mean ± SD age, 35.1
± 25.9 months; median age, 32.0 months) with optic pathway tumors (24
gliomas and 1 embryonal tumor), mostly located at the
hypothalamic-chiasmatic transition (n=21; 84.0%) with visual abnormalities
reported by parents (n=17; 68.0%). The mean grating acuity deficit was 0.60
± 0.36 logMAR (median, 0.56 logMAR). Visual impairment was detected
in all cases and was classified as mild in 10 (40.0%), moderate in 8
(32.0%), and severe in 7 (28.0%) children, along with increased interocular
differences (>0.1 logMAR) (n=16; 64.0%). The remarkable ophthalmological
abnormalities were nystagmus (n=17; 68.0%), optic disc cupping and/or pallor
(n=13; 52.0%), strabismus (n=12; 48.0%), and poor visual behavior (n=9;
36.0%).

In children with optic pathway tumors who were unable to perform recognition
acuity tests, it was possible to quantify visual impairment by
sweep-visually evoked potentials and to evaluate interocular differences in
acuity. The severity of age-based grating visual acuity deficit and
interocular differences was in accordance with ophthalmological
abnormalities and neuroimaging results. Grating visual acuity deficit is
useful for characterizing visual status in children with optic pathway
tumors and for supporting neuro-oncologic management.