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Abstract

Purpose
Given the possible role of spectral composition of light and myopia, this study aimed at investigating the variation in the spectral composition of ambient light in different (a) outdoor/indoor locations, (b) time of a day and (c) seasons.

Methods
The spectral power distribution (SPD), categorised into short (380–500 nm), middle (505–565 nm) and long wavelengths (625–780 nm), was recorded using a handheld spectrometer at three outdoor locations (‘open playground’, ‘under shade of tree’ and ‘canopy’) and three indoor locations (‘room with multiple windows’, ‘closed room’ and ‘closed corridor’). Readings were taken at five different time points (3-h intervals between 6:30 and 18:00 hours) on two days, each during the summer and monsoon seasons.

Results
The overall median SPD (IQR [25th-75th percentile] W/nm/m2) across the three outdoor locations (0.11 [0.09, 0.12]) was 157 times higher than that of the indoor locations (0.0007 [0.0001, 0.001]). Considerable locational, diurnal and seasonal variation was observed in the distribution of the median SPD value, with the highest value being recorded in the ‘open playground’ (0.27 [0.21, 0.28]) followed by ‘under shade of tree’ (0.083 [0.074, 0.09]), ‘canopy’ (0.014 [0.012, 0.015]) and ‘room with multiple windows’ (0.023 [0.015, 0.028]). The relative percentage composition of short, middle and long wavelengths was similar in both the outdoor and indoor locations, with the proportion of middle wavelengths significantly higher (p < 0.01) than short and long wavelengths in all the locations, except ‘canopy’.

Conclusion
Irrespective of variation in SPD values with location, time, day and season, outdoor locations always exhibited significantly higher spectral power than indoor locations. The relative percentage composition of short, middle and long wavelengths of light was similar across all locations. These findings establish a foundation for future research to understand the relationship between spectral power and the development of myopia.

Publication Type:	Article
Additional Information:	This is the peer reviewed version of the following article: Dhakal, R., Huntjens, B. , Shah, R. , Lawrenson, J. & Verkicharla, P. K. (2023). Influence of location, season and time of day on the spectral composition of ambient light: Investigation for application in myopia. Ophthalmic And Physiological Optics, 43(2), pp. 220-230, which has been published in final form at https://doi.org/10.1111/opo.13085. 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.
Subjects:	R Medicine > RE Ophthalmology
Departments:	School of Health & Psychological Sciences > Optometry & Visual Sciences
SWORD Depositor:	Symplectic Administrator

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