Seasonal Variation in Myopia Progression and Ocular Elongation

Abstract

Myopia progression rates were slower during the 6-month periods that included all of the summer vacation than would be expected assuming no seasonal effect. Ocular growth was also slower in the summer; but that trend, in most cases, was statistically significant only for changes in vitreous chamber depth and not for axial length.

Seasonal variation in myopia progression and axial elongation: an evaluation of Japanese children participating in a myopia control trial

“…We failed to confirm that myopia progression slows considerably in summer, as previously reported in the US and China [1,2]. Seasonal variations in myopia progression were not significant in Japanese children, although the latitude of the study center was almost the same as that in the US, and the ethnicity of our subjects was the same as that in China.…”

“…Therefore, the conclusion that the seasonal variation in myopia progression was small in Japanese children remains unchanged. Fulk et al [1] explain the mechanism of the seasonal variation they found as follows: myopia progression is stimulated by near work, and school activities such as reading and studying are less frequently engaged in during summer holidays. This is plausible because a lag of accommodation during near work produces a hyperopic defocus, and visual regulation of axial length eventually elongates the eye in order to compensate for the blurred image on the retina [8][9][10].…”

“…Fulk et al [1] report a 50-78 % (calculating using the refractive data they report) reduction in myopia progression in summer compared to winter. They think that such a seasonal variation may be caused by the different intensity and duration of near work (reading and writing) because near work is generally associated with school activity, and this typically decreases over the long summer vacation.…”

Vitamin D in Dry Eye and Myopia

“…However, studies in children conducted in different areas suggested that spending longer time outdoors is a greater protective factor as compared to physical activity (Dirani et al, 2009;Rose et al, 2008b). There has been the comparison of myopia progression between the seasons that have higher and lower hours of sunlight, demonstrating a slower progression of myopia in the sunnier seasons (Fulk et al, 2002). Also, dietary source of vitamin D has also been examined; for example, Taiwanese adult males have a daily intake of 3.39 μg vitamin D, while boys between the age of 6 and 12 only have 1.74 μg (Lee et al, 2008).…”

“…The measurements of ocular biometry and possibly accommodation in Experiment 3 and 4 for myopia study might have also been impacted due to the extended recruiting period. For example, axial elongation and vitreous chamber depth (Fulk et al, 2002) have been reported to be slower in summer months. Another factor that might also affect the measured vitamin D levels was the amount of skin being exposed to sunlight, which was directly influenced by clothing style (Kimlin et al, 2014).…”