Abstract
Purpose :
The aim was to use one of several devices available on the market to reliably and objectively measure the distance to a visual target over time, to assess its accuracy and to ascertain, via a Monte Carlo (MC) simulation and openly available population statistics, how this accuracy affects nearwork estimates in various environmental conditions for children.
Methods :
The accuracy of two wearable devices (Clouclip M2, HangZhou Glasson Technology Co., Ltd., China) was calculated at a range of distances (0–120 cm), further divided into four levels of accommodative demand in diopter units. Measurements were performed in two lighting conditions for two vision targets: bright, glossy and dark, matte computer screen. Absolute and relative errors were computed. Using MC simulations, a daily (nominal) model of diopter-hour (Dh) values was assessed, using media use statistics for five age groups: <2, 2–4, 5–8, 8–12 and 13–18 years (commonsensemedia.org, 2020, 2021). Another (measured) model was computed for distances adjusted for Clouclip relative errors. The two models were compared for each age group.
Results :
The distance values measured by the devices were overestimated, and the absolute error increased with distance. The relative errors (in %) presented in Tab. 1 varied and did not show any specific trend. The values of both nominal and measured models of diopter-hour values from MC simulations along with standard deviations for subsequent age groups are presented on Fig. 1. The difference between those two measures for the age groups are, respectively: 0.32 Dh, 0.63 Dh, 0.72 Dh, 1.08 Dh, 1.49 Dh per day, which corresponds to 16.5%, 15.4%, 3.7%, 11.4%, 9.6% relative difference.
Conclusions :
The sensors overestimate the distance leading to underestimation of the amount of nearwork. For the oldest group this error could be depicted as undetected time watching one average-length movie or playing on smartphone for 30 minutes each day. Underestimated value of nearwork may give a false sense of control to a parent concerned with progression of their child’s myopia.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.