An Innovative Technique to Evaluate Quantitative Pupillary Light Reflex by Dynamic Pupillometry using Infrared Videography

Abstract

Introduction: An innovative approach was designed to quantify the pupillary light reflex using infrared and white light illumination. This method is convenient to detect pupil edges, area and the diameter of pupil contour recorded in different ambient light conditions. Aim: To establish newer methodology, to quantify pupillary light reflex using image analysis. Materials and Methods: A standard web camera was modified as an Infrared camera to capture the real time pupil response to various intensities of illuminations. Pupillary response to a flash of light was video graphed and split into video frames. These images of the pupil thus obtained were subjected to an image analysing software. This methodology also provides a solution to exclude infra-red LED reflection within the pupil circle. The orientation of pupil within iris can be appreciated with this protocol. Results: The steps were tailored to measure various parameters of pupillary light reflex like minimum, maximum and mean pupil diameters. It also facilitates to calculate constriction and dilation velocities. The capture, cleavage and offline analysis of these video frames were done using all open source softwares. Conclusion: This simple, user-friendly, innovative technology can be used for quantifying the pupil response which can be used as an indicator for autonomic dysfunction.

Keywords

• autonomic nervous system
• baseline pupil diameter
• image j
• light-emitting diode
• maximum constriction velocity