Myopia and the Visual Environment

During postnatal development when the eye is still growing, an “emmetropization mechanism” uses the eye's refractive error to regulate the growth of the scleral shell to match the axial length of the eye to the focal plane. Despite this, in over 40% of Americans and up to 96% of groups in East Asia, the eye becomes too long for its own optics and is thus myopic. Even low amounts of myopia raise the risk of developing blinding conditions and refractive surgery does not change this. Thus, effective strategies to slow eye growth and reduce the prevalence of myopia are needed. One possible factor in the increasing incidence of myopia is the difference in the visual environment - the "image statistics" - between natural and man-made worlds, but to date there has been no good way to test this. This project will use a novel experimental technique and tree shrews, small diurnal mammals closely related to primates, to answer this question. Specific Aim 1. Determine the anti-myopia effectiveness of a range of real-world visual scenes. We will explore whether different visual scenes do or do not significantly affect emmetropization. Specific Aim 2: Develop an improved Repeated Low-level Red Light (RLRL) anti-myopia therapy. Recent results of `low level' red light therapy have shown impressive anti-myopia results, but these therapies are not low level but exceed established laser safety standards. Of the existing animal models only tree shrews and non-human primates have myopia reduced by red light; we will here attempt to develop more effective and safer short-time-exposure anti-myopia red light therapies. Specific Aim 3: Develop objective recommendations for lighting spectra. It is increasingly apparent that the spectrum of ambient light has powerful effects on refractive development, and common lighting sources vary widely in their spectrum. We will attempt to determine if different lighting spectra could be a risk factor for myopia.