Electrophysiological Analysis of Traumatic Optic Neuropathy and Traumatic Brain Injury Among Active Military.

Background: Traumatic Optic Neuropathy (TON) can cause persistent visual deficits and is a known sequala of Traumatic Brain Injury (TBI). Little is known regarding appropriate diagnosis, management, and treatment.

Methods: we performed a prospective cohort study with 356 active military personnel using electrophysiological Visual Evoked Potential (VEP) testing for TON in the context of known or suspected TBI. This was done with the intent to review and revise management protocol for patients who are susceptible to TON. This new VEP protocol was incorporated with kinetic and static visual field testing to uncover occult cases of TON previously missed in the current disability examination, as well as aid in evaluation of patients with borderline concussive cases that do not meet current diagnosis of mild, moderate, or severe TBI by the Veteran's Disability Exam.

Results: 80 patients were diagnosed with TON. Average age of TON patients was 37.4 years, with most patients being male. Of those patients with TON, 45% had reported TBI, whereas an additional 54% had suspected history of concussion. Patients presented with bilateral TON (65.8%, n=52), while unilateral TON cases occurred less frequently (35.4%, n=28). Visual field defects were apparent in both static and kinetic visual field testing in 54% of cases. VEP sensitivity in our study was 88%. Military parachute jumpers (paratroopers) represent the highest risk group for undiagnosed TBI and TON.

Conclusions: we recommend periodic static and kinetic visual field testing in high-risk individuals working in fields with high concussion rates. Focused collaboration for safer helmet design is imminent. By improving helmet design, we can reduce mTBI and related TON, as well as reduce costly medical care and disability payments after military discharge.