It is well established that refractive development is regulated by visual feedback. However, most optical treatment strategies designed to reduce myopia progression have not produced the desired results, primarily because some of our assumptions concerning the operating characteristics of the vision-dependent mechanisms that regulate refractive development have been incorrect. In particular, because of the prominence of central vision in primates, it has generally been assumed that signals from the fovea determine the effects of vision on refractive development. However, experiments in laboratory animals demonstrate that ocular growth and emmetropization are mediated by local retinal mechanisms and that foveal vision is not essential for many vision-dependent aspects of refractive development. However, the peripheral retina, in isolation, can effectively regulate emmetropization and mediate many of the effects of vision on the eye's refractive status. Moreover, when there are conflicting visual signals between the fovea and the periphery, peripheral vision can dominate refractive development. The overall pattern of results suggests that optical treatment strategies for myopia that take into account the effects of peripheral vision are likely to be more successful than strategies that effectively manipulate only central vision.
*OD, PhD, FAAO
College of Optometry, University of Houston, Houston, Texas, and Vision Cooperative Research Centre, Sydney, New South Wales, Australia.
This work was supported by grants from the National Eye Institute, National Institutes of Health, Bethesda, MD (EY 03,611, EY 07,551) and funds from the Vision Cooperative Research Centre and the Greeman-Petty Professorship, UH Foundation.
The author is a coauthor on patents related to peripheral optical treatment strategies for slowing myopia progression.
Received April 25, 2011; accepted June 2, 2011.
Earl L. Smith, III, College of Optometry, University of Houston, Houston, Texas 77204-2020, e-mail: email@example.com