We will collect data on the eye movements of a group of infants born between 36 and 44 weeks after conception. These infants will be enrolled between 4 and 24 weeks after birth and followed at 4-week (+/- 5 days) intervals until 28 weeks of age and then once a year until 3 years after birth. The infants will undergo a complete ophthalmic evaluation at each visit after they enroll. At all visits up to 28 weeks of age, they will also undergo analysis of eye movements. We also will monitor the development of ocular alignment and check to detect other visual system abnormalities. The study will provide basic knowledge about the cause of both normal and abnormal alignment of both eyes in infants in the first 28 weeks of life.