Abstract
Recent key observations have renewed interest the effect of ambient lighting on eye growth regulation and myopia: 1) outdoor activity appears to protect against the development of myopia and also slow myopia progression in humans, 2) shortening the night (dark period) appears to increase both the risk and progression of myopia, at least in law students, and 3) exposure to very bright light during the normal day attenuates form deprivation myopia in a variety of young animals, including chicks. This presentation will cover data from studies in which the length of the diurnal light cycle, its intensity and/or its wavelength characteristics were manipulated in the rearing of young chicks fitted with various types of defocusing lenses; some chicks were also subjected to iridectomy surgery to eliminate pupil size variation as a confounding factor when light levels are altered. These studies documented patterns of eye growth that reflected critical interactions between wavelength and intensity. Shortening the night (period of daily darkness) to model that experienced by students in the above study (2), had minimal effect on eye growth. The significance of these results for myopia control in humans will be discussed. Additional daily light exposure data recorded from college students will also be presented and discussed in the context of eye growth regulation and myopia.