Abstract
Purpose :
Sunlight exposure has been found to play an important role in myopia as a lifestyle modification factor. The purpose of this study was to evaluate the performance of an affordable wearable device for measurement of sunlight exposure in children and provide metrics through a dedicated mobile phone algorithm.
Methods :
A wearable device LUMINO-SD (India Patent Application no:202141040647) was built that can measure sunlight in terms of light intensity (LI), ultraviolet (UV) and infrared (IR) through an ambient light sensor, and the captured data was synchronised to a mobile phone algorithm. The light data were programmed to be captured once every minute between 7 am to 7 pm and stored. Validation of the measurements was done by placing the device in sunlight alongside a standard luxometer (Lutron LX-101A, USA). Eight protomodel devices were lab tested by placing in the following locations for 1 week each: outdoor sunlight, outdoor shade, indoor near window, indoor with artificial illumination. Hourly readings from 8 devices were averaged, analysed and plotted on a 12 hour graph. Real time data captured over 1 month were incorporated into Python software to define the thresholds of outdoor sunlight exposure duration (60% training, 40% testing). No human beings were used in the study at this point.
Results :
Hourly mean LI was found to range between 136 - 5344 lux indoors & 976 – 30,112 lux outdoors. There was statistically significant difference (p=0.046) between outdoor sunlight/outdoor shade and between indoor window/indoor artificial illumination(p=0.001). Hourly mean UV index ranged between 0-15 indoors and 2.5 - 64 in sunlight outdoors. Hourly mean IR was between 0-16 for indoors and 122-3764 for outdoors. The validation between luxometer and device was R2= 0.786. Machine learning using Python was reliable to define outdoor time based on testing accuracy of 67%.
Conclusions :
This prototype – LUMINO-SD provides reliable measurements on sunlight spectrum exposure of the wearer, based on real time data as thresholds. It could be a useful tool to study the correlation between sunlight, UV, IR and outdoor/indoor activities. It would be an effective tool for promoting outdoor time in kids and parental monitoring to manage the myopia epidemic in children worldwide. Because of the low cost manufacturing in India, the device would serve as an affordable one.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.