For years, scientists studying vision faced a problem: the tools used to track eye movements were either invasive and prone to failure or too imprecise for high-level research. Standard noninvasive methods track the center of the pupil and corneal reflections and compare their positions to estimate the direction of the gaze. But they frequently overestimated how much the eye drifted, making it difficult to tell exactly where a subject was looking.
To solve this, WaNBRC researchers helped develop OpenIrisDPI, a new kind of digital eye tracker that gives researchers a crystal-clear picture of exactly where the eye is focused. Instead of just looking at the pupil, it tracks multiple reflections within the eye, known as Purkinje images, to provide a pinpoint-accurate record of gaze. The tracker is in the Journal of Neuroscience Methods.
It was built by bioengineering graduate student Ryan Ressmeyer, who works in WaNBRC Neuroscience Unit Chief Greg Horwitz’s lab. When scientists tested this system, they found they could map the “receptive fields” of brain neurons with much greater sharpness than ever before. It essentially removes the “blur” from visual neuroscience, allowing us to see exactly how the brain processes the world.
“We need to revise our models of how vision works,” Horwitz said. For years, scientists have understood that they can show the same image and get a different response, or “noise,” from neurons in the visual system. “There’s been a lot of study about how noisy neurons are, and how you can try to figure out where that noise comes from and how neurons can do what they do despite noisiness. They answer might be they’re not that noisy at all.”
In the past, this kind of precision required specialized equipment costing upwards of $20,000. But OpenIris DPI is different because it is open-source and runs on consumer-grade hardware Ressmeyer built for a quarter of that price. By making these high-precision tools affordable and accessible, this technology ensures that more researchers can work on breakthrough treatments for vision and neurological disorders.
“When it comes to research, sometimes you want to have a company build a system for you. But other times I want something bespoke for research I’m doing, and other people have done the work to put it out there for free, and I can build on it and all I need are parts for a fraction of the cost,” Ressmeyer said.
WaNBRC neuroscientists: putting world-class science into the hands of the entire research community.
Get the plans and make one yourself via their GitHub wiki.