A Cross-Sectional Observational Study of the Relationship between Outdoor Exposure and Myopia in University Students, Measured by Conjunctival Ultraviolet Autofluorescence (CUVAF)

Abstract

Myopia is the most common refractive error worldwide. This cannot be explained by genetic factors alone, therefore, environmental factors may play an important role. Hence, the main objective of this study was to analyse whether outdoor exposure could exert a protective effect against the development of myopia in a cohort of young adults and to investigate ultraviolet autofluorescence (CUVAF), as a biomarker of time spent outdoors. A cross-sectional observational study was carried out using two cohorts. A total of 208 participants were recruited, 156 medical students and 52 environmental science students. The data showed that 66.66% of the medical students were myopic, while 50% of the environmental science students were myopic (p = 0.021). Environmental science students spent significantly more hours per week doing outdoor activities than medical students (p < 0.0001), but there was no significant difference with respect to near work activities between them. In both cohorts, the degree of myopia was inversely associated with CUVAF, and a statistically significant positive correlation was observed between spherical equivalent and CUVAF (Pearson’s r = 0.248). In conclusion, outdoor activities could reduce the onset and progression of myopia not only in children, but also in young adults. In addition, CUVAF represents an objective, non-invasive biomarker of outdoor exposure that is inversely associated with myopia.

Effect of Repeated Low-level Red Light on Myopia Prevention Among Children in China With Premyopia

“…34,35 The efficacy rate of these interventions at preventing myopia within 1 year ranged from 11.0% to 54.3%. [11][12][13][14][15][16][17][18][19][20][21][22] Repeated low-level red-light (RLRL) therapy delivered by a device emitting 650-nm visible red light has been proposed as an alternative myopia control intervention. [36][37][38][39][40][41] Recent research has reported increased blood flow and stabilization of axial elongation among children after the RLRL intervention, which might suggest that RLRL therapy could ameliorate scleral hypoxia and thus prevent the development of myopia.…”

“…Currently, several interventions have been proposed to prevent the onset of myopia, such as increased outdoor time, 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 reducing activities done at a short working distance, 18 , 19 , 20 , 23 , 24 , 25 , 26 , 27 , 28 Chinese eye exercises, 29 , 30 , 31 , 32 , 33 and low-dose atropine. 34 , 35 The efficacy rate of these interventions at preventing myopia within 1 year ranged from 11.0% to 54.3%.…”

“… 34 , 35 The efficacy rate of these interventions at preventing myopia within 1 year ranged from 11.0% to 54.3%. 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 …”

Conjunctival Ultraviolet Autofluorescence as a Biomarker of Outdoor Exposure in Myopia: A Systematic Review and Meta-analysis.

“…Eight studies obtained the CUVAF measurement by custom-made photographic systems 22,[30][31][32][36][37][38][39] and one study using the Heidelberg OCT system. 29 All studies report that myopes have signi cantly smaller CUVAF areas than non-myopes.…”

“…Since it was rst described, different research groups have studied CUVAF area as a biomarker of sun exposure, moreover, recent publications have shown an inverse relationship between CUVAF area and myopia. 22,[29][30][31][32] Therefore it promises to be an inexpensive, reproducible, quick and easy method to use in a routine ophthalmology and optometry practice unlike other tests. However, these studies included very heterogeneous populations in terms of age and geographic location, which could in uence CUVAF area.…”