These researches are aimed at finding a practical method for identifying infants and very young children who are at risk for developing amblyopia. We propose to continue our current photographic screening of young infants using previously gathered normative data to identify infants between 2 months and 2 years of age with aberrant refractive development. With subsequent visual acuity testing we will identify amblyopes and determine those aspects of refractive development correlated with amblyopia. We will also screen handicapped infants and children who have been shown to have 4x normal the prevalence of refractive errors. In order to study the combined roles of accommodation and convergence in bringing a sharp image on the infant fovea we propose to study these together using dual video cameras, one recording direction of gaze and the other recording photorefractive reflexes using a high quality video recorder with a split screen attachment. We will use this apparatus to characterize the normal relationships between accommodation and convergence in infants in their first year of life. We will also study the role of convergence on accommodation by inference, by studying accommodation in monocular infant viewing and comparing it with binocular viewing. Because our earlier work has shown that astigmatism is an important feature of infant refractive development and may be useful in steering accommodative feedback loops we propose to look at accuracy of focusing without chromatic cues in astigmatic infants and adults. We will also study the focusing ability of adult subjects with varying degrees of high order aberrations. In order to study the high frequency dynamics of accommodation we propose to build a computer driven video photorefractometer. When ready, this instrument will be used to characterize accommodation in the accommodation and convergence experiments. Lastly we will continue our animal studies on the origin of the retinoscopic reflex and the physiological optics of owl eyes, the latter in an effort to understand the very high quality optics of those eyes and their mechanism of accommodation.
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