Objective Measurement of Sustained Pupillary Constriction: A Pilot Study Using an App-Based Pupilometer

Abstract

Background: The pupillary reaction is controlled by the two main branches of the autonomic nervous system, namely the parasympathetic and sympathetic nervous systems. New discoveries in pupil research has identified that intrinsically photosensitive retinal ganglion cells have an impact on pupillary constriction, particularly sustained pupillary constriction. In the current paper, an objective measurement of sustained pupillary constriction versus the inability to maintain sustained pupillary constriction are observed. The variability in the sustained pupillary constriction, i.e. Alpha Omega pupil, can be objectively identified with the use of modern technology. Case Examples: Two female subjects were adapted to dim illumination, and then two objective pupil measurements of the right eye using Reflex – PLR Analyzer by BrightLamp© (Indianapolis, IN, USA) with sustained illumination were obtained. Subject 1, a 25 year-old-female, demonstrated normal ability of the pupil to constrict and sustain constriction for 10 seconds. She was used as a control for subject 2. Subject 2, a 27 year-old-female, demonstrated the inability to sustain pupillary constriction. She reported being under great psychological stress. Her pupil began to re-dilate between 2 and 3 seconds after the initial constriction. Conclusion: Objective pupillometry can be used to assist in many diagnoses and provides the clinician invaluable information on the state of the individual, and qualifications of sustained pupillary constriction can now be assessed in an objective manner.