Visual Dysfunctions and Symptoms During the Subacute Stage of Blast-Induced Mild Traumatic Brain Injury

Abstract

The purpose of the present study was to assess the occurrence of visual dysfunctions and associated symptoms in active duty warfighters during the subacute stage of blast-induced mild traumatic brain injury (mTBI). A comprehensive visual and oculomotor function evaluation was performed on 40 U.S. military personnel, 20 with blast-induced mTBI and 20 without. In addition, a comprehensive symptom questionnaire was used to assess the frequency of visual, vestibular, and neuropsychiatric-associated symptoms. The most common mTBI-induced visual dysfunctions were associated with near oculomotor deficits, particularly large exophoria, decreased fusion ranges, receded near point of convergence, defective pursuit and saccadic eye movements, decreased amplitude of accommodation, and monocular accommodative facility. These were associated with reduced reading speed and comprehension and an increased Convergence Insufficiency Symptom Survey score. Photosensitivity was a common visual dysfunction along with hearing, balance, and neuropsychiatric symptoms. The oculomotor testing for warfighters suspected of blast-induced mTBI should include, at a minimum, the assessment of near lateral and vertical phorias, positive fusional vergence, stereoacuity, near point of convergence, amplitude of accommodation, monocular accommodative facility, saccades, and pursuit eye movements. A reading test should be included in all routine exams as a functional assessment of the integration of oculomotor functions.