Accommodation and Defocus in the Infant Visual System

Project Summary/Abstract: Postnatal development of the human visual system is dependent on visual experience. Abnormal visual experience during infancy and childhood can lead to strabismic misalignment of the eyes and amblyopia. The goal of the proposed research is to understand how the visual system uses its available natural experience to coordinate eye alignment and focus during infancy and early childhood, in the context of prevention of these clinical conditions. There are two interrelated projects: i) To understand how depth information across the visual field can be used to coordinate eye alignment and focus during early postnatal development, and how common clinical disorders during early childhood can disrupt that coordination. ii) To understand which image structure across the visual field is capable of driving a conjugate orienting eye movement during early postnatal development, and how the binocular aspects of that movement can be disrupted by common clinical disorders. These projects will test hypotheses and build models to determine the amounts of conditions such as anisometropia that can disrupt ocular motor control as a function of human postnatal age. Previous studies of the development of focusing accommodation responses and aligning vergence responses have concentrated on 2D stimuli in the central visual field, while the brain needs to function in the full field, dynamic, three-dimensional natural environment in order for a patient to develop typical vision. It is the interaction between this visual environment and the quality of retinal visual experience that motor control can provide that defines a patient’s experience-dependent development. The results will provide i) evidence-based clinical guidelines for the prevention of amblyopia and strabismus ii) constraints for biologically-inspired simulations of the development of vision.