Investigating the Pupillary Light Reflex with Python Software
Researchers at the University of Oxford Institute of Biomedical Engineering have released a novel research platform for applications concerning the human pupillary light reflex (PLR).
The platform of hardware contains a Spectra Tune Lab light source (STLAB) from LEDMOTIVE that integrates 10 different LED channels. STLAB has an advanced closed-loop control system based on a mini spectrometer to monitor and control the temporal and spectral deviations of light.
PyPlr is a Python library developed to control the research-grade, video-based eye-tracker system, synchronizing the light source for stimulus, extraction of features, cleaning the image, and analysis of pupil data.
This investigation was led by Joel T. Martin, Joana Pinto, Daniel Bulte & Manuel Spitschan and is available in open access in the journal Behavior Research Methods. Their paper is entitled: “PyPlr: A versatile, integrated system of hardware and software for researching the human pupillary light reflex.” This paper explains how full-field, homogenous stimulation of the retina can be realized with a low-cost, integrating sphere that serves as an alternative to a more complex Maxwellian view setup.
The research platform demonstrates its capabilities with two example applications:
- pupillometer-style measurement and parametrization of the pupillary light reflex (PLR) to flashes of white light
- comparing the post-illumination pupil response (PIPR) to flashes of long and short-wavelength light.
The system holds promise for researchers who would favor a flexible approach to studying the PLR and the ability to employ a wide range of temporally and spectrally varying stimuli, including simple narrowband stimuli.
Caption for the above figure of the stimulation and measurement system:
- Integrating sphere constructed from two acrylic half-domes, housed, and stabilized with a wooden fixing plate
- Inside coating of Avian-B high reflectance paint to scatter light homogenously
- STLAB light source mounted above entry port
- Pupil Core eye-tracking headset
- Laptop running Pupil Capture and custom Python software. Photograph taken and used with permission
LEDMOTIVE produces multiple color LED light sources and pocket spectrometers. Its software manages the output spectrum of the light modules, while the electronics can control several light sources to provide the desired blended and dynamic output. LEDMOTIVE’s Bluetooth Android-based spectrometer provides spectral and color data.
To request more information or a quotation for any LEDMOTIVE products, contact IL Photonics.