Synopsis Of Research:
Regulation of Eye Growth and Refractive State My laboratory works on the visual regulation of postnatal eye growth and the development of refractive state. The eye continues to develop from birth to maturity in such a way that as it grows in size it undergoes adjustments of its optical components and its refractive state. These adjustments are usually coordinated so that eyes grow toward emmetropia (emmetropization). Occasionally emmetropization does not occur and the eye becomes nearsighted (myopic) or farsighted (hyperopic). We are interested in how emmetropization works and why it occasionally leads to refractive errors. Our earlier work, and that of others, has established that imposed defocused images can influence the growth of the eye and the development of refractive errors. We are currently interested in several aspects of this experimental ocular growth regulation including the characteristics of the visual stimuli influencing eye growth, the way the stimuli are spatially and temporally integrated, how accommodation interacts with this integration. In collaboration with Dr. Jody Summers Rada (University of Oklahoma) we are also studying the biochemical basis of the ocular growth response. We hypothesize that the development of refractive state is determined by a confluence of several interacting factors including the shape of the eye, the spatial pattern of refractive state across the retina, and the temporal characteristics of visual stimuli experienced. In addition to these, there may be individual inherited differences in eye shape and peripheral refractive state as well as the area of retina involved in the integration of the visual growth signal, and the gain of the eye growth controller. Such a multi-factorial system would explain why it is so difficult to predict who will become myopic, and who will progress (and how to treat them effectively). These studies have relevance to tens of millions of patients with refractive errors. Myopia is a leading cause of blindness but its control is an old and still controversial topic. We believe that our current work will help provide answers to several clinically relevant questions regarding the development and control of myopia, the association between near work and myopia, and the identification of risk factors and predictors.

Current Or Representative Publications:

Troilo, D., Totonelly, K., and Harb, E. (2009) Imposed anisometropia, accommodation, and regulation of refractive state. Optometry and Vision Science, 86(1):31-39. (PMC2702514)

Hendrickson, A., Troilo, D., Djajadi, H., Possin, D., and Springer, A. (2009) Expression of synaptic and phototransduction markers during photoreceptor development in the marmoset monkey Callithrix jacchus. Journal of Comparative Neurology, 512:218-231. (NIHMS 105010)

Shelton, L., Troilo, D., Lerner, M., Gusev, Y., Brackett, D.J., and Rada, J.S. (2008) Microarray analysis of choroid/RPE gene expression in marmoset eyes undergoing changes in ocular growth and refraction. Molecular Vision, 14:1465-1479. (PMC2504533)

Troilo, D., Quinn, N., and Baker, K. (2007) Accommodation and induced myopia in marmosets. Vision Research, 47(9):1228-1244. (PMC1892168)

Harb, E., Thorn, F., and Troilo D. (2006) Characteristics of accommodative behavior during sustained reading in emmetropes and myopes. Vision Research, 46(16):2581-2592. (PMC1892179)