Reproducibility of the pupillary light reflex over short intervals in psychiatric patients and community volunteers.

The pupillary light reflex (PLR) is a method for measuring dynamic responses within the autonomic nervous system, and would have potential value as a point of care test in a psychiatry clinic if reproducible results could be obtained in a short period of time. We collected PLR from adult community volunteers and depressed outpatients with the purpose of demonstrating (1) that valid data could be obtained >90% of the time from both the community volunteers and the patients, and (2) that reproducible results could be obtained with repeated measurement over short periods of time. Valid data were captured for 90.3% of 76 participants, allowing for two attempts of the PLR per participant. Success rates were similar for depressed patients and community volunteers. Eighteen of these 76 participants provided repeated paired measurements after 5 and 10 minutes of dark adaptation, producing high correlations for maximal constriction velocity (MCV) between assay 1 and 2 (Pearson's r=0.71, p<0.001), but there was a significant 8% increase in velocity for MCV between assay 1 and 2 (∆=0.34+0.59 mm/sec, p<0.05). In contrast, PLR measurements were stable when tested in a separate cohort of 21 additional participants at 10 and 15 minutes of dark adaptation with a MCV Pearson's correlation of r=0.84, p<0.001, with a non-significant 1% difference between the two time points. These findings indicate an acceptable rate of collecting valid and reproducible PLR data when contrasting 2 measurements of PLR after 10 or 15 minutes of dark adaptation in depressed and suicidal patients. This article is protected by copyright. All rights reserved.