Purpose: Traumatic brain injury involving loss of consciousness has focal effects in the
human brainstem, suggesting that it may have particular consequences for eye movement
control. This hypothesis was investigated by measurements of vergence eye movement
parameters.
Methods: Disparity vergence eye movements were measured for a population of 123 normally
sighted individuals, 26 of whom had suffered diffuse traumatic brain injury (dTBI) in
the past, while the remainder served as controls. Vergence tracking responses were measured
to sinusoidal disparity modulation of a random-dot field. Disparity vergence step
responses were characterized in terms of their dynamic parameters separately for the
convergence and divergence directions.
Results: The control group showed notable differences between convergence and divergence
dynamics. The dTBI group showed significantly abnormal vergence behavior on
many of the dynamic parameters.
Conclusion:The results support the hypothesis that occult injury to the oculomotor control
system is a common residual outcome of dTBI.