In survey led by pediatric ophthalmologist Graham Quinn, M.D.,of the Scheie Eye Institute and Children's Hospital of Philadelphia, 34 percent of chilfren under age 2 who slept with just a night light on were myopic. The greater the amount of light, the higher the number of myopic children. For instance, 55 percent of children under 2 who regularly slept with the room light on had myopia.
Only 10 percent who slept in darkness were myopic. Since vision in chicks is affected by light, researchers reasoned, maybe the same holds true for young children.The survey team used a questionnaire to determine how parents of children ages 2-16 lit their child's room. They found the light effect only accured before age 2; lighting patterns at the child's present age did not seem to affect vision. The report, which appeared in the May 13 issue of the journal Nature, stoppedshort of saying light causes myopia in sleeping todlers. Rather, wrote the authors, this study asks whether there's a "critical period" for refractive development analogous to that for visual function. Their conclusion? The authors closed with a guarded warning that "it seems prudent that infants and young children sleep at night without artificial lightning" while the phenomenon is examined further.
Karla Zadnik, O.D. of Ohio State University said that the study published in Nature doesn't control for enough variables, and leaves itself open to a lot questions.