Eye Tracking Glasses Allow for Real-World Intermittent Exotropia Evaluation

Eye tracking glasses may be used to quantify intermittent exotropia severity, according to a study published in the American Journal of Ophthalmology. The technology may also potentially determine the number of times an individual switches between orthotropia and exotropia in a day, the eye that is favored for fixation on visual targets, and other features that are not easily measured during a clinical examination.

Researchers from the University of California, San Francisco included 44 study participants (age range, 3-79 years; 25 men and boys) diagnosed with intermittent exotropia in the prospective, cross-sectional study conducted between 2020 and 2022. The team fit participants with eye tracking glasses, which recorded vergence angle and exotropia occurrence during a mean 5 hours and 35 minutes of wear. 

The eye tracking data revealed that 31 study participants had intermittent exotropia — the remaining 13 individuals had exotropia less than 1% and were classified as having exophoria. Among the patients with intermittent exotropia, the average exotropia was 19.3° and ocular deviation occurrence was 40%. A moderate correlation between exotropia magnitude and occurrence (r, 0.59) was noted. A majority of participants (n=35) had intermittent exotropia occurrences overreported by their families, according to the report. 

“The invention of eye tracking glasses has made it possible to quantify the percentage of time that an intermittent exotropia is present,” according to the researchers. “As eye tracking glasses become easier to use and lower in cost, ambulatory recording may eventually become a routine outpatient test, permitting measurement of the exact occurrence of this disorder in each patient.”

Study limitations include a small sample size, convenience samples obtained from 1 ophthalmology practice, and a short study duration.