Understanding the effects of mild traumatic brain injury on the pupillary light reflex

Abstract

The pupillary light reflex represents an optimal visual system to investigate and exploit in the mild traumatic brain injury (mTBI) population. Static and dynamic aspects of the pupillary light reflex were investigated objectively and quantitatively in the mTBI population. Pupillary responsivity was found to be significantly delayed, slowed and reduced, but symmetrical in nature, and with a smaller baseline diameter, as compared with normals. Several pupillary parameters also discriminated between those with versus without photosensitivity. Thus, dynamic pupillometry provides several objective biomarkers for the presence of mTBI and photosensitivity, gives insight into the global sites of neurological dysfunction and possible related mechanisms, and should result in improved patient care.

Letter to the Editor. Pupillometry and neurotrauma: point-of-care technologies versus point-of-care techniques

“…First, regarding the baseline conditions of pupil constriction velocity, latency to constriction, maximum size, and percentage change, in the reported study maximum constriction velocity and dilation velocity were recorded in controls before the events of head trauma and serve as baseline data. In addition, pupil dilation velocity, percentage change in pupil size, and maximum constriction velocity parameters showed statically significant alterations after a mild traumatic brain injury (mTBI), findings that have already been confirmed by Ciuffreda et al 3 However, the changes of these parameters could not be interpreted to be due only to anatomical changes or neuron pathway dysfunction. As already described by Shetty et al, 4 about 27% of the patients after an mTBI develop white matter changes.…”

Potential for the development of light therapies in mild traumatic brain injury

“…The cumulative action of this pathway is pupillary constriction. For a complete review of the effects of mTBI on the pupillary light reflex, including NIF pathway contributions, please see [ 41 ].…”

Evaluation of two portable pupillometers to assess clinical utility

“…Assessment of the pupillary light reflex (PLR) following a suspected concussion injury is an essential component of the physical examination [ 1 ]. Within the past 30 years, portable pupillometers have become available that can analyze the PLR waveform [ 2–5 ].…”