Development and validation of a ‘MyLyt’ wearable light tracking device

Abstract

Purpose We developed a clip‐on light tracker (MyLyt) for estimating light exposure in real time. This study aimed at validating and investigating the feasibility of using MyLyt in children and adults. Method The study was conducted in two phases. Phase 1 involved validation against a factory‐calibrated digital lux meter in three separate conditions: controlled environmental set‐up, outdoors and indoors where intra‐test (two measurements by the same tracker), inter‐test (measurements among trackers) and inter‐device (MyLyt tracker and lux meter) validations were conducted. Phase 2 involved a feasibility study where MyLyt was used in a real‐world setting by 21 adults and 8 children. Participants were asked to log their real‐time movements in an ‘activity diary’, which were correlated with the lux levels measured by the tracker. Results A strong positive correlation and non‐significant difference in the recorded mean illuminance levels were observed during intra‐test (inter‐class correlation: 1.00, p = 0.99), inter‐test (0.91–1.00, p > 0.15) and inter‐device (0.91–1.00, p > 0.56) validation in all three testing conditions (p > 0.49), except the indoor location. While the lux level measured by MyLyt was significantly higher than that of the lux meter (p < 0.01) in the indoor locations, differences were minimal and clinically insignificant. A Bland–Altman plot showed a minimal mean difference (95% limits of agreement) between the MyLyt tracker and lux meter in all three conditions (controlled environmental set‐up: 641 [−949, 2230], outdoor: 74 [−2772, 2920] and indoor: −35 [−151, 80] lux). Phase 2 validation showed an expected illuminance level against the corresponding location with high sensitivity (97.8%) and specificity (99%) to accurately differentiate between outdoor and indoor locations. Conclusion The MyLyt tracker showed good repeatability, strong correlation and comparable values with the lux meter in the three tested conditions, making it suitable for tracking light exposure patterns for both research and clinical purposes.

Using Light Meters to Investigate the Light-Myopia Association – A Literature Review of Devices and Research Methods

“…290–1060 nm peak: ca. 450 nm Instantaneous light intensity measured every 20s, sampling every 1 min – but 3 data points sampled every 1 min for the light measurements MyLyt 53 Clip-on encapsulated logger Illuminance (lux) 0–88,000 lux Range: 400–850 nm Peak: ca. 600–655 nm Instantaneous light measurement with freely configurable logging frequency from 1s onward Vivior Monitor 54 Glasses clip Illuminance (lux) red, green, blue components of visible ambient light as well as infrared channel ambient light color temperature UV exposure 0–100,000 lux (graphical display 0–10,000 lux, export and statistics include full range) Range: ca.…”

“…35h; charging via cable, magnetically attached to the device, with USB plug on other end Smartphone app and Bluetooth connection needed for device initialization and data upload; after data acquisition, data uploaded to online database via the app splashproof No: device worn on glasses and needs overnight charging if worn for multiple days FitSight f , 48 , 49 n/a Sony Smartwatch 3 battery rechargeable via Mini USB n/a Sony Smartwatch 3 waterproof at 1.5 m for 30 min (per IP68) Yes (provided that the battery life is sufficient) HOBO Pendant Temp/Light data 50 Size: 48 × 33 x 23 mm weight: 18 g Changeable battery (3-Volt CR-2032 lithium battery); typically lasts 1 year with logging intervals > 1 min; with continuous logging at fastest rate (1 s), battery lasts 2 weeks Optic USB base station, coupler and software needed for device initialization and data access; data access via software on a computer Waterproof (30 m from −20 to 20 °C, 10 m at 50 °C) Problematic: usual wearing options (eg as a necklace or pinned to clothing) likely cause discomfort and/or safety issues Mumu 51 , 52 Size: 600 × 400 x 200 mm weight: ca. 65 g Rechargeable battery; battery life > 20 h; charging via Mini USB Device automatically starts data acquisition once it is powered on; data is uploaded to a private cloud after data acquisition Splashproof Yes (though battery life may restrict multiple day wear) MyLyt 53 Size: 47 × 37 x 16.4 mm weight: 50 g Rechargeable Lithium polymer battery; battery life 7 days at a sampling rate of 60s; charging via USB Automatic device initialization when program is loaded; data is stored manually on a flash memory Splashproof (presently; can be made waterproof per IP67) Problematic: device being pinned on clothing below neck likely to cause discomfort and/or safety issues Vivior Monitor 54 Size: 60 × 19 x 14 mm weight: 14 g Rechargeable lithium ion polymer battery (120 mAh capacity); allows for data collect...…”

“…The MyLyt 53 is a prototype developed at the LV Prasad Eye Institute (Hyderabad, India) to track real-time light exposure. It records illumination (lux) against real time.…”

“…Further improvements, eg, a smartphone connection for data transfer or reducing size and weight, are planned. 53 …”

Light exposure profiles differ between myopes and non-myopes outside school hours

“…The details of MyLyt tracker related to technical specifications, validation and safety, and precaution measures have been described elsewhere. 31 The tracker was clipped onto the school uniform (during school time) or the casual wear (outside of school time) worn by the participant, below the neck at the level of the upper thoracic region. They were instructed to immediately relocate the trackers onto new clothes after changing the school uniform.…”