Abstract
Purpose :
Recent studies justify the rise of late onset myopia in young people due to unhealthy digital habits (too much near work time, too near face-device distance, too low ambient illumination). University students are an especially vulnerable group due to the high volume of near vision tasks they normally perform in indoor illumination conditions. We performed a study to collect objective digital habits data in a university population and investigate their potential correlation with clinical subjective refraction.
Methods :
70 subjects aged 21±3 years, in their first or second year of university completed a clinical optometric examination, and used their own personal smartphones to install an app that continuously (at 1 Hz) measured their digital habits: face-device distance, ambient light level, daily screen time (measured only while looking at the screen); daily number of times the device was looked at (minimum interval between events of 20”. A statistical inference analysis was performed to know the relation between digital habits and the spherical equivalent of their refraction (SER), axial length (AL), and smartphone reading distance (SRD).
Results :
A total of 60M of data points corresponding to 15M seconds, with at least 3600 s of data per subject, were obtained. Average daily screen time was 1.4±1.2h, with a maximum of 6.2 h, while the daily number of times the device was looked at was 74±59. The average intersubject face-device distance was 363±56 mm, while the SRD was significantly, (p<1010) smaller, 296±59 mm. Mean+SD illuminance was 311±225 lux. The mean standard deviation of the intrasubject distance was 83 mm and illuminance was 714 lux. Lower SER values (larger myopia) and larger AL values correspond to a nearer face-device distance of lower ambient illumination, but the correlation was very weak (R2<0.03).
Conclusions :
Face-device distance and ambient illumination varied among subjects but also within the individual subjects’ data, indicating that a continuous measurement is needed to sample and estimate the real accommodating effort and illuminance. Within the context of the cohort size and study duration it was not possible to predict a strong correlation between SER or AL, with high variability in the digital habits data between subjects. A longitudinal study of several years would be needed to learn the effects of digital habits on myopia.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.