Influence of refractive error on pupillary dynamics in the normal and mild traumatic brain injury (mTBI) populations

Abstract

PurposeThere have been several studies investigating static, baseline pupil diameter in visually-normal individuals across refractive error. However, none have assessed the dynamic pupillary light reflex (PLR). In the present study, both static and dynamic pupillary parameters of the PLR were assessed in both the visually-normal (VN) and the mild traumatic brain injury (mTBI) populations and compared as a function of refractive error.MethodsThe VN population comprised 40 adults (22–56 years of age), while the mTBI population comprised 32 adults (21–60 years of age) over a range of refractive errors (−9.00 D to +1.25 D). Seven pupillary parameters (baseline static diameter, latency, amplitude, and peak and average constriction and dilation velocities) were assessed and compared under four white-light stimulus conditions (dim pulse, dim step, bright pulse, and bright step). The Neuroptics, infrared, DP-2000 binocular pupillometer (30 Hz sampling rate; 0.05 mm resolution) was used in the monocular (right eye) stimulation mode.ResultsFor the majority of pupillary parameters and stimulus conditions, a Gaussian distribution best fit the data, with the apex centered in the low myopic range (−2.3 to −4.9D). Responsivity was reduced to either side of the apex.ConclusionsOver a range of dynamic and static pupillary parameters, the PLR was influenced by refractive error in both populations. In cases of high refractive error, the PLR parameters may need to be compensated for this factor for proper categorization and diagnosis.

Symptoms of Autonomic Dysfunction Among Those With Persistent Posttraumatic Headache Attributed to Mild Traumatic Brain Injury: A Comparison to Migraine and Healthy Controls

“…Although not specifically studies of PTH, prior studies have identified symptoms of dysautonomia among those with TBI . Studies of autonomic dysfunction following mTBI have assessed heart rate variability, pupillary light reflex, arterial pulse wave, and graded exercise testing . One such study showed head‐upright tilt table abnormalities similar to postural orthostatic tachycardia syndrome (POTS) in youth with persistent post‐concussion syndrome .…”

“…22,28,46 Studies of autonomic dysfunction following mTBI have assessed heart rate variability, 19 pupillary light reflex, arterial pulse wave, and graded exercise testing. 26,27,35 One such study showed head-upright tilt table abnormalities similar to postural orthostatic tachycardia syndrome (POTS) in youth with persistent post-concussion syndrome. 24 Another study showed a group of 8 patients who developed POTS based on head-upright tilt table test after TBI.…”

“…Investigations that deeply phenotype individuals with PTH and compare the PTH phenotype to migraine might lead to identification of features that are more representative of PTH compared to migraine. Based on our clinical observations and published literature demonstrating evidence for autonomic dysfunction following mild traumatic brain injury (mTBI) and in those with migraine, we hypothesized that PTH is often accompanied by autonomic symptoms such as orthostatic intolerance, and that symptoms of autonomic dysfunction are more severe among those with PTH compared to those with migraine …”

“…Based on our clinical observations and published literature demonstrating evidence for autonomic dysfunction following mild traumatic brain injury (mTBI) and in those with migraine, we hypothesized that PTH is often accompanied by autonomic symptoms such as orthostatic intolerance, and that symptoms of autonomic dysfunction are more severe among those with PTH compared to those with migraine. [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] The objective of this study was to compare symptoms of autonomic dysfunction between individuals with persistent posttraumatic headaches (PPTH) attributed to mTBI vs those with migraine vs healthy controls using the Composite Autonomic Symptom Score 31 (COMPASS-31) questionnaire. [38][39][40] We also interrogated correlations between COMPASS-31 scores and headache characteristics (headache days per month and years with headache) to investigate the association between headache burden and autonomic dysfunction in the PPTH and migraine groups and correlations between lifetime number of TBIs and COMPASS-31 scores among those with PPTH.…”

iPhone-based Pupillometry: A Novel Approach for Assessing the Pupillary Light Reflex

“…Previous reviews 26 , 27 have highlighted the utility of portable pupillometry systems in a variety of fields including surgery, 26 , 28 critical care, and anesthesiology. 26 – 30 In large part, the value of these instruments is in their ability to quantitatively evaluate a physiological response that has previously been assessed by qualitative observations.…”