Abstract
Purpose :
Myopia is one of the leading causes of vision loss globally. Numerous studies have shown that myopia is associated with near viewing behaviors, which currently include reading, communicating and entertainment on hand-held electronic devices. Hyperopic defocus is believed to trigger active eye growth, and when children view near targets the image plane is likely to be behind the retina due to accommodative lag. We hypothesized that children employ close viewing distances that vary with the type of stimulus being displayed on a mobile device.
Methods :
Viewing distance between the face and device were obtained from a commercial software (VisionApp) when children viewed a hand-held electronic device (Google Pixel 3). Twenty children (10 myopic; 10 emmetropic) between 6 and 12 years of age watched a movie (from YouTube Kids) with room lights on (226 Lux), watched a movie with lights off (0.1 Lux), read small text (1.45mm, 8 pt type, 1M), read large text (3.0mm, 16 pt type, 2M), and played a video game (Minecraft), in a random sequence. Viewing distance was continuously monitored for 5 minutes for each task at a sample rate of 15 f/s. Average distances were reported once per second.
Results :
Viewing distance was accurately reported over the range of 50 cm to 6.7 cm (-15 Diopters) with a RMSE of 2.7mm and high tolerance to phone rotation (±20 degrees). Mean viewing distance across all subjects and all tasks was 24cm, which was reduced to 21 cm when children read small sized text and increased to 27cm when watching movies in dark or playing video games. Viewing distance was often stable over the 5-minute period (mean SD = 4.8cm).
Conclusions :
Children using mobile electronic devices employ closer viewing distances than often reported for adults (24cm vs. 40-50cm). This close viewing distance may make them prone to sustained hyperopic defocus secondary to increased accommodative lags at near.
This is a 2020 ARVO Annual Meeting abstract.