Visual electrodiagnostic findings in mild traumatic brain injury

Patients with traumatic brain injury (TBI) frequently exhibit varied forms of visual system dysfunction including: binocular, oculomotor, accommodative, refractive error shift, visual field loss, and visual perceptual deficits. A 5-year collaborative study between optometry and ophthalmology was initiated to follow documented mild TBI patients utilizing diagnostic methods to assess the quantity and quality of visual system deficits and recovery. A group of patients with mild TBI receiving optometric rehabilitation were compared with a group of age-matched, gender-matched, and headsize-matched TBI patients not receiving such treatment. Eighteen patients diagnosed with mild TBI underwent a treatment regimen of optometric rehabilitation (group I); 32 patients diagnosed with mild TBI did not receive optometric rehabilitation (group II). Pattern visually evoked cortical potential (VECP) testing and electroretinography (ERG) evaluation were utilized initially, repeated 6-12 months later and then 12-18 months after baseline. All TBI patients' VECP and ERG results were compared to age-matched, headsize-matched controls. Once the ERG had been used to exclude retinal involvement, identification of visual pathway dysfunction was possible with the VECP. Full-field ERG results in all groups were not remarkable and not sensitive for patients with mild TBI. Initial testing results revealed that 72% of those TBI patients in group I demonstrated VECP waveform abnormalities and 81% of those patients in group II showed waveform dysfunction. In the testing performed 12-18 months later, 38% of group I TBI patients, after receiving a treatment regimen of optometric rehabilitation, showed VECP waveform abnormalities; 78% of group II TBI patients demonstrated waveform abnormalities. VECP evaluation in patients with mild TBI can provide a useful and reliable tool for objective assessment of visual system deficit and recovery. Significant differences in visual system recovery were shown when comparing group I and group II.