Prevalence of myopia in people who slept under bright light at night until the age of 3 years

This was a cross-sectional case-control study in which the effect of night-time ambient light on prevalence of myopia in patients with a history of exposure to night-time light during sleep throughout the first three years of their lives was investigated in 2008. Two hundred children aged 3-15 years who were brought to our eye clinic at boo-Ali hospital for ophthalmic examination investigated as case group. Also, 200 sex and age matched children were randomly selected as control group. Following completion of questionnaire routine ophthalmic examinations including visual acuity test, refraction, ophthalmoscopy, IOP, slit lamp test, and keratometry were performed by an ophthalmologist and an optometrist. Data were analyzed using SPSS and t-test. There were 126 (63%) females and 74 (37%) males in each group. The results of this study showed that of 200 children with the history night-time ambient light exposure during sleep throughout the first three years of their lives, 196 (98%) were with myopia (-0.25 to -4D), three with hyperopia and one with normal sight. Among control group, 154 (77%) were myopic (-0.25 to -1.25D) and 46 (23%) hyperopic. Our data indicated that exposure to night-time light during sleep within the first three years of life increase the risk of early myopia by 1.6 times higher than those in control group with no exposure to night-time light during sleep within the first three years of life (p<0.05).