Chronic stage mild traumatic brain injury subjects have visual system deficits regardless of self-reported vision problems.

Abstract

Purpose : Vision problems are common in traumatic brain injury (TBI) patients. These symptoms can be chronic and are reported regardless of TBI severity. We performed a prospective, observational clinical study using a battery of quantitative and objective clinically available assessments that could underlie these self-reported symptoms.

Methods : 65 adult subjects were recruited; 28 with mTBI (mean age: 35 years) and 34 non-mTBI controls (mean age: 39 years) and included both males and females. The average time since last TBI was 7 years (± 6 years). Best corrected visual acuity (BCVA), tonometry, fundoscopy, oculomotor, contrast sensitivity, humprey visual field (HVF), visual evoked potentials (VEP), optical coherence tomography (OCT), magnetic resonance imaging (MRI) of brain and optic nerve were performed, as well as symptom assessment using the neurobehavioral symptom inventory (NSI). The outcome measures between groups were analyzed using linear regression models that matched age and sex and addressed within patient cluster effect.

Results : Structurally, the retinal nerve fiber layer (RNFL), optic nerve and visual cortex were significantly thickened in the mTBI group. Functionally, 64% of individuals with mTBI had an oculomotor dysfunction, a VEP P100 amplitude 11% lower and a binocular summation index 32% higher than control group. Additionally, a 2-sample Kolmogorov-Smirnov on distributions of z-scores from test batteries with or without MRI and VEP data were performed. Scores were significantly different from control in 64% of mTBI participants when MRI and VEP data was not included, whereas this number increased to 75% when these assessments were included. Deficits in accommodation and near point of convergence did not correlate closely with self-reported vision problems. A trend for correlation to self-reported symptoms was detected for the OCT and MRI findings.

Conclusions : Performing a targeted battery of clinical assessments will increase likelihood of diagnosing deficits within the visual system from TBI, even in the chronic population. Future studies should explore applying machine learning approaches to data from this population as deficits are likely subtle, but consistent.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.