The relationship between contact lens ultraviolet light transmittance and myopia progression: a large-scale retrospective cohort study.

Background: The prevalence of myopia is increasing dramatically around the world, and many studies have suggested the possibility that ultraviolet (UV) light is effective to prevent the onset and progression of myopia. However, UV is a risk factor for diseases that cause refractive errors such as cataract and pterygium. In this study, we evaluated the relationship between UV exposure and myopia progression.

Methods: The dataset consisted of a total of 337 396 eyes of patients in the 12-to-29-year age range, who were prescribed soft contact lenses (SCL) for refractive error at Okada Eye Clinic in Japan between 2002 and 2011. They were tracked over a five-year period and did not change the type of SCL. In this retrospective cohort study based on medical records, we divided patients into two groups, one prescribed SCL with UV protection (UV-SCL), and another prescribed SCL without UV protection (UV + SCL).

Results: Change in refractive power over five years was measured and results compared. It was -0.413 diopter (D) in the UV-SCL group and -0.462 D in the UV + SCL group. Thus, the progression of myopia was slower in the UV-SCL group. The results were also analyzed separately by gender and degree of myopia at the time of initial prescription, which all showed significant differences (P < 0.001).

Conclusion: Results suggest that UV exposure may advance myopia. Further research is needed to investigate the underlying mechanisms that could explain this.