Researchers at the University of California San Diego have developed a smartphone app that can allow people to screen for ADHD and other neurological diseases and disorders by recording closeups of their eye.

The app uses a near-infrared camera, which is built into newer smartphones for facial recognition, along with a regular selfie camera to track how a person’s pupil changes in size. These pupil measurements could be used to assess a person’s cognitive condition.

The technology was described in a paper presented at the 2022 ACM Computer Human Interaction Conference on Human Factors in Computing Systems (CHI 2022).

“While there is still a lot of work to be done, I am excited about the potential for using this technology to bring neurological screening out of clinical lab settings and into homes,” said Colin Barry, an electrical and computer engineering PhD student at UC San Diego and the first author of the paper, which received an Honorable Mention for Best Paper award.

“We hope that this opens the door to novel explorations of using smartphones to detect and monitor potential health problems earlier on.”

Pupil size can provide information about a person’s neurological functions, recent research has shown. For example, pupil size increases when a person performs a difficult cognitive task or hears an unexpected sound.

Measuring the changes in pupil diameter is done by performing what’s called a pupil response test.

The test could offer a simple and easy way to diagnose and monitor various neurological diseases and disorders. However, it currently requires specialized and costly equipment, making it impractical to perform outside the lab or clinic.

Engineers in the Digital Health Lab, led by UC San Diego electrical and computer engineering professor Edward Wang, collaborated with researchers at the UC San Diego Center for Mental Health Technology (MHTech Center) to develop a more affordable and accessible solution.

The app, developed by the UC San Diego team, uses a smartphone’s near-infrared camera to detect a person’s pupil.

In the near-infrared spectrum, the pupil can be easily differentiated from the iris, even in eyes with darker iris colors. This enables the app to calculate pupil size with sub-millimeter accuracy across various eye colors.

The app also uses a color picture taken by the smartphone’s selfie camera to capture the stereoscopic distance between the smartphone and the user. The app then uses this distance to convert the pupil size from the near-infrared image into millimeter units.

The app’s measurements were comparable to those taken by a device called a pupillometer, which is the gold standard for measuring pupil size.

“When developing technologies, we must look beyond function as the only metric of success, but understand how our solutions will be utilized by end-users who are very diverse,” said Wang, who is also a faculty member in the UC San Diego Design Lab.

The Digital Health Lab is continuing the work in a project to enable similar pupillometry function on any smartphone rather than just the newer smartphones.

Future studies will also involve working with older adults to evaluate home use of the technology.

The work was funded by the National Institute of Aging.

Hana Julian is a licensed clinical psychotherapist specializing in ADHD across the life span, offering teletherapy sessions. Email or send a text via WhatsApp to +972-54-310-1933 to find out more.