Abstract Body: Introduction In stroke evaluation, the pupil light reflex (PLR) is a vital indicator of neurological function. The effects of pilocarpine, a cholinergic agonist, can be used to simulate small unreactive ‘'pin-point’' pupils in healthy subjects. Pilocarpine causes miosis (pupil constriction), altering several key pupil parameters and sensitivity to light. We tested a novel pupillometry device (AI Pupillometry System, Solvemed Inc.) designed to ensure reliable PLR measurements, independent of the distance between the device and the patient’s eye, even in pin-point pupils.
Materials and Methods Smartphone flashlight is used to induce the pupillary response, while simultaneous distance measurement allows real-time calibration of pupil size, ensuring accuracy regardless of measurement distance. 189 healthy volunteers were recruited to validate the device’s performance, and 8 patients were administered pilocarpine to induce miosis. Pupillary constriction and dilation metrics were recorded. A regression analysis was conducted to assess the influence of eye-to-device distance on the measurements, with and without pilocarpine. Data was analysed to assess the accuracy, repeatability, and sensitivity of the device.
Results We showed consistent performance across all measured parameters, with only small impact on pupillary metrics, specifically latency (ß=0.18, p<0.05), amplitude (ß=-0.00, p<0.05), constriction velocity (ß=0.01, p<0.05) across different measurement distances. For subjects treated with pilocarpine, latency (ß=-0.09, p<0.07), amplitude (ß=0.00, p=0.28), constriction velocity (ß=0.00, p=0.71) were not significantly affected by measurement distance. However, pilocarpine significantly affected pupil size, constriction velocity and dilation velocity, with a marked reduction in pupil size and a decrease in the dynamic range. Regression analysis confirmed that changes in the measurement distance had a consistent but only very small impact on accuracy in natural pupil states and an inconsistent and non-significant impact in pharmacologically induced pupil states.
Conclusion This innovation enhances the reliability and consistency of pupillary exams. Pilocarpine primarily affects pupil size, constriction velocity, and dilation velocity, and increases light sensitivity by limiting the pupil’s ability to dilate in response to darkness. The distance of the device from the eye had minimal impact on measurement accuracy, even in pin-point pupils.