Strabismus is misalignment of one eye in relation to the other, resulting in failure of the 2 eyes to simultaneously focus on the same image and loss of binocular vision. Strabismus affects 2% to 4% of the population and can result in amblyopia, which is often not discovered in time to initiate effective treatment. Thus, an understanding of the genetic underpinnings of strabismus may help identify patients at risk early enough to prevent disability and may lead to new preventive or therapeutic approaches.