PROJECT SUMMARY Binocular vision is important for many everyday activities, and its development relies on the coupling of accurate binocular eye movements with stereoscopic fusion. However, these mechanisms do not develop properly in 2-5% of the population, who have chronic impairments in the form of strabismus and amblyopia. Evaluating and treating strabismus is particularly challenging due to the limited availability of automated assessments or rehabilitation procedures for moving eyes in multiple postures. A scientific understanding of the sensory and oculomotor impairments in strabismus will inform clinical assessment and lay the foundation for new evidence-based therapies. Therefore, the goals of this project are to translate laboratory-based eye tracking procedures to the clinic where they can automatically quantify the magnitude of strabismus across different gaze postures, and then to relate these measurements to functional impairments in binocular vision. A third goal is to use the same methodological techniques to examine whether sensory and motor deficits in strabismus can be manipulated using a novel oculomotor adaptation procedure. Aim 1 will draw on both well-established clinical assessment methods and high-speed eye tracking to quantify the magnitude and variability of ocular misalignment across different gaze postures in observers with and without strabismus. In addition, patients’ binocular visual deficits will be measured at the same postures to examine the relationship between the magnitude of misalignment and binocular visual function for a given gaze direction. This variation is important to capture, as it has been shown that normally-sighted observers without strabismus exhibit ocular misalignment, and even stereoblindness, at certain gaze directions. Aim 2 will draw on the techniques developed in Aim 1 to evaluate the perceptual and motor effects of dichoptic oculomotor adaptation. Previous work with normally-sighted observers has shown that eye movement amplitudes can be adaptively recalibrated in opposite directions in the two eyes, but the short-term perceptual consequences of this adaptation have not been investigated in either normally-sighted subjects or patients with strabismus. The results of Aim 2 will provide insights into oculomotor plasticity in patients with strabismus, a key step in developing non-invasive therapies.