Because vision is strongly related to brain development, a baby's eyes grow fast in the first six months of life. While a result, as your baby's brain develops at a rapid pace, so do her eyes. By one year old, your infant will have seen with clarity for about 200 times, and be able to recognize over 10,000 different objects. For most babies, clear vision begins around 3-4 weeks after birth. At this age, babies are starting to focus on lights behind their eyelids and move their eyes from side to side to see more clearly. They'll continue to develop their eye muscles and lenses until they reach adulthood. However, because children spend much of their time looking at screens, parents need to be aware that focusing abilities don't fully develop until a person reaches their 20s. In addition to seeing clearly, other signs of healthy vision include: noticing colors more deeply, being able to distinguish shapes, and being able to read without difficulty. If you notice your child struggling with any of these tasks, make sure she sees an ophthalmologist for a comprehensive eye exam before she starts school.