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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.

Publication Type:	Article
Additional Information:	This is the peer reviewed version of the following article: Dhakal, R, Rudrapankte, JR, Chittajallu, HSN, Lawrenson, JG, Huntjens, B, Shah, R, et al. Development and validation of a ‘MyLyt’ wearable light tracking device. Ophthalmic Physiol Opt. 2022; 00: 1– 9, which has been published in final form at http://dx.doi.org/10.1111/opo.13061. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.
Publisher Keywords:	Wearable light tracker, time outdoor, light exposure, validation, myopia
Subjects:	R Medicine > RE Ophthalmology
Departments:	School of Health & Psychological Sciences > Optometry & Visual Sciences
SWORD Depositor:	Symplectic Administrator

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