A new wearable device for supporting myopia epidemiology studies

The prevalence of myopia is increasing worldwide and is closely associated with nearwork. Reliable and objective estimates of nearwork, based on measuring the distance to a visual target, are limited to only a few commercially available wearable instruments that have limitations for laboratory research and large epidemiological studies.

The aim was to design a fully controllable, low-cost, and low-energy-consumption wearable device and evaluate its accuracy, compare it with a commercially available device, and evaluate through simulations how this accuracy affects estimates of the amount of nearwork in different environmental conditions.

The devices were comprehensively assessed and their accuracy at several distances related to nearwork was calculated. A Monte Carlo simulation with global media usage statistics was used to estimate the impact of device accuracy on the amount of nearwork expressed in diopter-hours.

The proposed device showed superior performance with measuring errors ranging from -3.20 to 1.50 cm and being independent of the measured distance, as compared with a commercial device that showed distance-dependent errors ranging from -0.33 cm to as much as 57 cm. A Monte Carlo simulation illustratively showed that the proposed device overestimates the daily amount of nearwork by only 2.1% (0.5 Dh), whereas the commercial device underestimates it by 7.1% (1.9 Dh).

The proposed device meets the stringent requirements for laboratory applications as well as those required in large epidemiological studies. It demonstrated high and stable accuracy in a variety of tested conditions and showed lower errors than those exhibited by the benchmark commercial device. Errors in the measurement of the amount of nearwork may give false signals to parents, clinicians, and researchers about the relative myopiagenic risks of nearwork experienced by children.