Variable transmission lens influences on the dynamics of pupillary light reflexes

This study examined the influence of liquid crystal variable transmission lenses on pupillary light reflexes in response to sudden bright light onset. Participants were exposed to bright light while pupil size was monitored using an eye tracker; eyewear was configured across four transition conditions: constant low-light filtering, constant high-light filtering, variable-light filtering in response to light detection and a control condition without eyewear. Before light onset, pupil diameter was largest in the high-filter condition, medium in the variable- and low-light filtering conditions and smallest in the control condition. Following light onset, the low-light filtering and control conditions, and the high-light filtering and variable-light filtering conditions converged over time. Critically, automatically transitioning between low- and high-light filtering reduced the magnitude (approximately 0.2 mm) and duration (approximately 360 ms) of the pupillary response relative to constant low-light filtering.