Traumatic Brain Injury: Ophthalmic Complications

For the second consecutive year, the Association for Research in Vision and Ophthalmology hosted a special session on traumatic brain injury (TBI) during its Annual Meeting in Seattle, WA, on April 30, 2016. While ophthalmic complications of TBI was the primary focus of the session, several points relevant to the neurology community were discussed during the session.

The session opened with the state of the science address by Ann McKee, MD, professor of neurology and pathology at Boston University. In her presentation, McKee focused on chronic traumatic encephalopathy (CTE), a syndrome that she sees often in athletes who experience concussions. A postmortem diagnosis, CTE is characterized by perivascular hyperphosphorylated tau (p-tau) deposits around small blood vessels of the brain. These pathognomonic lesions were found in deceased athletes of all ages, starting in the third decade of life. Clinically, individuals with CTE display memory impairment, impulsivity, violent behavior, executive dysfunction, and changes in vision. Since p-tau deposits have been found in both the eye and brain, eye examination may offer a way to diagnose CTE in patients with this clinical presentation.

A reliable diagnostic method is very much needed, repeatedly stressed Lee Goldstein, MD, PhD, also of Boston University, during his presentation. “The diagnostic is absolutely essential for getting a therapeutic; they are hand and glove,” urged Goldstein as he shared his work on temporal dynamics of TBI. Using a mouse model of TBI, Goldstein and colleagues described the evolution of changes in the nervous system after trauma, in particular, activation of microglia; they found a striking difference in the state of retinal microglia before and after trauma. Thus, the retinal neuroinflammation may evolve as a diagnostic measure of the pathological changes in the brain following TBI as the states of the two are closely related.

While measurement of microglia activation may not be clinically feasible just yet, retinal thickness can be easily measured in the clinical setting using optical coherence tomography. Randy Kardon, MD, PhD, director of neuro-ophthalmology at the University of Iowa, discussed the use of this method to measure thickness of the retinal layers in patients and healthy individuals. He reported a significant reduction in thickness of retinal layers in veterans with a history of mild TBI and Division I college football players, compared to patients with controlled glaucoma and healthy individuals. Kardon proposed the change in retinal thickness over a period of years to decades as a plausible noninvasive measure of trauma-related neuropathology.

If anyone in the audience remained skeptical of the importance of this work, the story told by Master Sergeant Eric Marts convinced them without medical terminology or highly significant research data. Marts sustained multiple concussions during his lengthy deployment, which ultimately cost him vision. Unaware of the possibility of this outcome and despite experiencing early changes in vision, he continued to serve and sustain injuries. Marts called on the audience to “take under their wing” those who protect our country by raising awareness and improving diagnostic and management of trauma among the military personnel. His speech received a standing ovation.

U.S. Congressman Jim McDermott, who opened the session, called TBI a huge unrecognized problem and expressed hope that the session stirs interest from legislators, the research community, and the public. A brilliant lineup that evoked both scientific curiosity and urge to protect those most at risk, the session was definitely a success by this and any measure.