Soon after birth, most infants develop the optimal refractive error (i.e., "clinical" emmetropia) in both eyes that is then maintained throughout childhood and into early adult life. However, for reasons not currently understood, a significant and increasing proportion of the population develop abnormal refractive errors. The long-term goal of our research program is to provide a better understanding of the etiology of common human refractive errors (e.g., myopia or nearsightedness) and ultimately to develop effective optical treatment strategies that reduce the impact of refractive errors.
The specific aims of our proposed research are to determine how visual experience affects refractive development and to characterize the operational properties of the vision-dependent mechanisms that regulate eye growth. Since many of the required experiments can not be conducted in humans, but our purpose is to generate knowledge that can be applied to human development, these experiments will be conducted using rhesus monkeys. Controlled rearing strategies, optical and ultrasonographic measurement techniques, and magnetic resonance imaging will be used to determine: 1) the effects of high ambient light levels on emmetropization and vision-dependent changes in eye growth, 2) the influence of relative peripheral myopia on central axial growth and refractive development, and 3) whether relative myopic defocus that is simultaneously superimposed on competing hyperopic defocus (a very strong stimulus for growth) can retard axial growth and promote hyperopia. The proposed experiments focus on fundamental issues concerning the manner in which visual experience influences refractive development and are an important step in determining how and to what extent visual experience contributes to the genesis of common human refractive errors. More importantly, the results of these studies will potentially provide the foundation for new treatment and management strategies for human refractive errors.
Refractive errors, in particular myopia or nearsightedness, are a significant public health concern because, in addition to the high costs and the complications associated with traditional optical and surgical correction strategies, refractive errors can lead to permanent sensory disorders and ocular abnormalities causing blindness. Moreover, recent evidence suggests that the prevalence of myopia, and consequently its impact on society, is increasing rapidly. Hence, effective treatment strategies to reduce or eliminate refractive errors are urgently needed.
|Tao, Xiaofeng; Zhang, Bin; Shen, Guofu et al. (2014) Early monocular defocus disrupts the normal development of receptive-field structure in V2 neurons of macaque monkeys. J Neurosci 34:13840-54|
|Smith 3rd, E L; Hung, L-F; Arumugam, B (2014) Visual regulation of refractive development: insights from animal studies. Eye (Lond) 28:180-8|
|Shen, Guofu; Tao, Xiaofeng; Zhang, Bin et al. (2014) Oblique effect in visual area 2 of macaque monkeys. J Vis 14:|
|Arumugam, Baskar; Hung, Li-Fang; To, Chi-Ho et al. (2014) The effects of simultaneous dual focus lenses on refractive development in infant monkeys. Invest Ophthalmol Vis Sci 55:7423-32|
|Smith 3rd, Earl L; Hung, Li-Fang; Arumugam, Baskar et al. (2013) Negative lens-induced myopia in infant monkeys: effects of high ambient lighting. Invest Ophthalmol Vis Sci 54:2959-69|
|Smith 3rd, Earl L; Campbell, Melanie C W; Irving, Elizabeth (2013) Does peripheral retinal input explain the promising myopia control effects of corneal reshaping therapy (CRT or ortho-K) & multifocal soft contact lenses? Ophthalmic Physiol Opt 33:379-84|
|Zhu, Xiaoying; McBrien, Neville A; Smith 3rd, Earl L et al. (2013) Eyes in various species can shorten to compensate for myopic defocus. Invest Ophthalmol Vis Sci 54:2634-44|
|Smith 3rd, Earl L; Hung, Li-Fang; Huang, Juan et al. (2013) Effects of local myopic defocus on refractive development in monkeys. Optom Vis Sci 90:1176-86|
|Zhang, Bin; Tao, Xiaofeng; Shen, Guofu et al. (2013) Receptive-field subfields of V2 neurons in macaque monkeys are adult-like near birth. J Neurosci 33:2639-49|
|Smith 3rd, Earl L (2013) Optical treatment strategies to slow myopia progression: effects of the visual extent of the optical treatment zone. Exp Eye Res 114:77-88|
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