OpenIrisDPI: An Open-Source Digital Dual Purkinje Image Eye Tracker for Visual Neuroscience

Abstract

BackgroundVideo-based eye trackers are widely used in vision science, psychology, clinical assessment, and neurophysiology. Many such systems track the pupil center and corneal reflection (P-CR) and compare their positions to estimate the direction of gaze. However, P-CR eye trackers are often too imprecise for applications with stringent eye tracking quality requirements. New methodWe present OpenIrisDPI, an open-source plugin for the OpenIris frame-work that implements dual Purkinje image (DPI) tracking. OpenIrisDPI supports simultaneous pupillography, a technique widely used in perceptual psychology and neuroscience, and it enables direct comparison between P-CR and DPI signals. ResultsData collected from macaque monkeys using OpenIrisDPI show that the P-CR method overestimates the amount of fixational drift between saccades compared to DPI. The accuracy of the DPI signal was further validated using high-density extracellular recording of neurons in the lateral geniculate nucleus. Compensating for the effects of fixational eye movements using DPI signals produced sharper estimates of neuronal receptive fields than using simultaneously collected P-CR signals. Comparison with existing methodsOpenIrisDPI is provided as open-source software and operates on consumer-grade hardware, making it more accessible than previously described DPI eye trackers and less costly than many P-CR systems. To our knowledge, OpenIrisDPI is the first eye tracker to perform both pupillography and DPI eye tracking. ConclusionOpenIrisDPI makes high-precision eye tracking readily available to the research community. It is well suited for visual neuroscience applications, where accurate knowledge of the retinal image during experiments is critical. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=105 SRC="FIGDIR/small/649589v2_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@596dd2org.highwire.dtl.DTLVardef@139027borg.highwire.dtl.DTLVardef@1d1e526org.highwire.dtl.DTLVardef@11b321c_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIOpenIrisDPI is a new open-source eye tracking system. C_LIO_LIOpenIrisDPI tracks the pupil, corneal reflection, & fourth Purkinje image at 500 Hz. C_LIO_LIDual Purkinje image-based eye tracking is more precise than pupilbased tracking. C_LIO_LIDPI improves receptive field characterization of LGN neurons in fixating macaques. C_LI