Study suggests visual system affected in patients with mild traumatic brain injury

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The results of a new study¹ suggested that the visual system is affected in patients with mild traumatic brain injury (TBI), even in patients who do not report visual disturbances, according to Marselle Rasdall, MD, from Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville. The research team reported their results in JAMA Ophthalmology.

It is noteworthy that patients with mild TBI often report visual issues despite normal results of visual acuity measurements and fundus examinations.

In light of that, Rasdall and colleagues conducted a case-control study to determine if visual dysfunction associated with mild TBI can be diagnosed using a battery of assessments across the visual pathway.

Their prospective observational study was conducted at a level 1 trauma research hospital from May 2018 to November 2021. Adult patients were included who had a recorded best-corrected visual acuity and normal fundus examination. All patients had a history of mild TBI; controls had no such history. The cases and controls were matched for sex and age.

Patients were excluded if they had a history of ocular, neurologic, or psychiatric disease; moderate-severe TBI, a recent TBI, metal implants, were younger than 18 years, and were pregnant.

The main outcomes were the Neurobehavioral Symptom Inventory and measurements of oculomotor function, optical coherence tomography, contrast sensitivity, visual-evoked potentials, visual field testing, and magnetic resonance imaging, according to the investigators.

Findings in TBI patients

The researchers reported their findings in 28 patients (15 men; mean age, 35.0 years) with mild TBI and 28 controls (19 women; mean age, 35.8 years).

The chief finding was that 78% of patients with a TBI had deficits in ocular motor function and/or the primary visual pathway.

The investigators reported, “Participants with mild TBI showed a reduced prism convergence test breakpoint (−8.38; 95% confidence interval [CI], −14.14 to −2.62; P = 0.008) and recovery point (−8.44; 95% CI, −13.82 to −3.06; P = 0.004). Participants with mild TBI also had decreased contrast sensitivity (−0.07; 95% CI, −0.13 to −0.01; P = 0.04) and an increased visual-evoked potential binocular summation index (0.32; 95% CI, 0.02-0.63; P = 0.02).”

Machine learning identified subtle differences across the primary visual pathway, including the optic radiations and occipital lobe regions, independent of the visual symptoms, Rasdall and colleagues said.

They concluded, “The results of this case-control study suggested that the visual system was affected in individuals with mild TBI, even in those who did not self-report vision problems. These findings support the utility of a battery of assessments or machine-learning approaches to accurately diagnose this population.”

Reference:

1. Rasdall MA, Cho C, Stahl AN, et al. Primary visual pathway changes in individuals with chronic mild traumatic brain injury. JAMA Ophthalmol. 2024;Published online November 27; doi:10.1001/jamaophthalmol.2024.5076T-MR-brief for online-trauma