A team at the University of California San Diego has developed a smartphone app that can precisely measure changes in pupil size as a potential method to assess a variety of neurological conditions and disorders, including Alzheimer’s disease and ADHD. The technique relies on the near-infrared cameras that newer smartphones use for facial recognition. The system is simple to use, and could let people participate in at-home diagnostics of conditions previously diagnosed in other ways. The researchers consulted older adults while designing the system, to ensure that it is suitable for independent use by this group of patients.
Changes in your pupil size in response to various stimuli may reveal more about you than you realize, including your cognitive condition when performing complex tasks. Such information could be useful in diagnosing or monitoring neurological conditions, although this field is still in its relative infancy for such applications. However, to date, measuring pupillary responses was only possible using bulky and expensive equipment in a hospital.
This latest technological endeavor aims to make this technique accessible to all at home, using a smartphone. “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, a researcher involved in the study. “We hope that this opens the door to novel explorations of using smartphones to detect and monitor potential health problems earlier on.”
Newer smartphones contain a near-infrared camera that is typically used for facial recognition, along with a regular selfie camera. The researchers use both of these cameras to perform smartphone-based pupillometry. The near-infrared spectrum allows the camera to more easily distinguish between the pupil and surrounding iris at sub-millimeter levels of accuracy. This can be difficult for regular cameras, particularly if the iris is a dark color.
Meanwhile, the app uses the regular selfie camera to measure the distance between the camera and the user’s face, allowing the system to calculate the diameter of the pupil in millimeters. The measurements the system can obtain are comparable in their accuracy to those obtained using a gold-standard pupillometer.
The researchers also consulted older adults while designing the system to make sure that it was easy to use. “For us, one of the most important factors in technology development is to ensure that these solutions are ultimately usable for anyone,” said Barry. “This includes individuals like older adults who might not be accustomed to using smartphones.”
See a video about the system below.
Study in CHI Conference on Human Factors in Computing Systems, 2022 Proceedings: At-Home Pupillometry using Smartphone Facial Identification Cameras