Smartphone app could screen for neurological diseases through your eyes

How would you like to screen yourself for Alzheimer’s disease, attention deficit hyperactivity disorder (ADHD) and other neurological diseases from the comfort of your home? 

Researchers at the University of California San Diego have developed a smartphone app that records close-ups of people’s eyes to assess cognitive conditions. 

The app uses a near-infrared camera that comes built-in with newer smartphone models for facial recognition and a regular selfie camera to track how a person’s pupil changes in size. 

These pupil measurements could evaluate a person’s cognitive condition, a news release notes.

The technology is explained in a paper that was presented at the ACM Computer Human Interaction Conference on Human Factors in Computing Systems (CHI 2022) in New Orleans between April 30 and May 5.

“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,” says 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.”

Recent research has shown pupil size can provide information about a person’s neurological functions. For example, when a person hears an unexpected sound or performs a difficult cognitive task their pupil size increases, the news release explains.

A pupil response test measures the changes in pupil diameter and offers an easy way to diagnose and motor various neurological diseases and disorders. 

But the pupil response test at the moment requires specialised and expensive equipment, which means it’s impractical to carry out outside the lab or clinic.

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

“A scalable smartphone assessment tool that can be used for large-scale community screenings could facilitate the development of pupil response tests as minimally-invasive and inexpensive tests to aid in the detection and understanding of diseases like Alzheimer’s disease,” says Eric Granholm, a psychiatry professor at UC San Diego School of Medicine and director of the MHTech Center.

“This could have a huge public health impact.”

The app uses a smartphone’s near-infrared camera to recognise a person’s pupil, which works even in eyes with darker iris colours. Therefore, it can calculate pupil size with sub-millimetre accuracy across various eye colours. 

The app also uses a colour picture taken by the smartphone’s selfie camera to catch the stereoscopic distance between the smartphone and the user. It then uses this distance, the news release notes, to convert the pupil size from the near-infrared image into millimetre units.

For anyone who wonders about the accuracy of a smartphone app, its measurements were comparable to the gold standard for measuring pupil size – a pupillometer.

The research team also included several features in the app to render it more user-friendly for seniors.

“For us, one of the most important factors in technology development is to ensure that these solutions are ultimately usable for anyone. This includes individuals like older adults who might not be accustomed to using smartphones,” says Barry. 

The app was designed with the participation of older adults who would self-administer pupil response tests. The interface included voice commands, image-based instructions, and a cheap, plastic scope to help the user position their eye within the view of the smartphone camera.

“By testing directly with older adults, we learned about ways to improve our system’s overall usability and even helped us innovate older adult specific solutions that make it easier for those with different physical limits to still use our system successfully,” says Wang, who is also a faculty member in the UC San Diego Design Lab. 

“When developing technologies, we must look beyond function as the only metric of success, but understand how our solutions will be utilised by end-users who are very diverse.”

The Digital Health Lab is carrying on with this research in a project to enable similar pupillometry function on any smartphone instead of simply the newer smartphones. 

Future studies will also include older adults to assess home use of the technology. 

In addition, the researchers will work with older individuals with mild cognitive impairment, according to the news release, to test the app as a risk screening tool for early stage Alzheimer’s disease.

THUMBNAIL PHOTO: UC San Diego Digital Health Lab