From the day your baby's born, her eyes will aid her physical, mental, and emotional development by allowing her to take in information – a little bit at first, and eventually much more – about the world around her.
When it develops
Unlike a baby's hearing, which is fully mature by the end of his first month outside the womb, the sense of sight develops gradually over 6 to 8 months, at which point your baby will see the world almost as well as you do.
While your newborn's eyes are physically capable of seeing just fine at birth, his brain isn't ready to process all that visual information, so things stay pretty fuzzy for a while. As his brain develops, so does his ability to see clearly, giving him the tools he needs to understand and manage his environment. Though your baby starts out life being able to see only as far as your face when you hold him, his range of clarity grows steadily, month by month.
How it develops
At first your baby can't focus farther than 8 to 12 inches away – just far enough to make out the face of the person holding her. She can detect light, shapes, and movement beyond that, but it's all pretty blurry right now. Appropriately enough, your face is the most fascinating thing to your baby at this age (followed by high-contrast patterns such as a checkerboard), so be sure to give her plenty of up-close time.
At birth, your baby didn't know how to use his eyes in tandem, so they may have wandered randomly or even crossed now and then. This month or next, he'll be able to consistently focus both eyes and track a moving object. A rattle passed in front of his face will often transfix him as he explores this newfound ability. He may also enjoy playing eyes-to-eyes with you: With your face very close to his, move your head slowly from side to side, with your eyes and his eyes locked.
Your baby could see colour from birth, but she had difficulty distinguishing similar tones, such as red and orange. That's one reason she preferred black-and-white or high-contrast patterns. For the next few months, her brain's at work learning to distinguish colours. As a result, she'll probably begin to show a preference for bright primary colours and more detailed and complicated designs. Encourage this development by showing her pictures, photos, books, and toys. For the next couple of months, she'll also be perfecting her object-tracking skills.
Your baby's beginning to develop depth perception. Until now, it was tough for him to locate an object's position, size, and shape, then get a message from his brain to his hand to reach out and grasp it. At 4 months, he has both the motor development to handle the task and the maturity in his brain circuitry to coordinate all the moves needed to accomplish it. You can help him practice by offering him easy-to-grasp toys like rattles (otherwise he'll go for your easy-to-grasp hair, glasses, or earrings).
Your baby is getting better at spotting very small items and tracking moving objects. She may even be able to recognize something after seeing only part of it. This is evidence of her budding understanding of object permanence (knowing that things exist even when she can't see them at the moment), which is why she loves to play peekaboo. She can probably distinguish between similar bold colours and will start working on more subtle differences in pastels.
Your baby's vision – between 20/200 and 20/400 at birth – is almost adult in its clarity and depth perception at this point. Though his attention is more focused on objects that are close by, his vision is strong enough to recognize people and objects across the room. His eyes are probably close to their final colour, though you may see subtle changes later.
Make sure the doctor takes a look at your child's eyes at every check up. The doctor will check the structure and alignment of your child's eyes and her ability to move them correctly and look for signs of congenital eye conditions or other problems. Be sure to let your baby's doctor know if either you or your partner has a strong family history of serious eye problems – particularly problems that surfaced in childhood.
Studies show that babies prefer human faces to all other patterns and images, so let your baby study your face by keeping it close to hers (especially when she's a newborn). At about 1 month, almost anything you pass in front of your baby's face is likely to fascinate her. The stores are packed with developmental toys, but you can do just as well with simple toys and everyday household objects.
Move a rattle or something bright and plastic from side to side in front of her face. Then try moving it up and down. This should attract her attention, although most babies won't be able to smoothly follow vertical motion until they're 3 or 4 months old. Also take note of other things that interest your child visually – the ceiling fan, birds or fluttering leaves in the garden or children jumping rope.
Encourage your baby's interest in primary colours and pastels as she gets older. Some great eye-catchers include primary-coloured mobiles (hung out of reach), colourful posters (put one near her changing table), and visually striking board books.
When to be concerned
The doctor will check your baby's eyes at routine visits, but if you notice something that doesn't seem quite right, be sure to mention it. For example:
Your baby doesn't track an object (your face or a rattle) with both eyes by the time he's 3 or 4 months old.
Your baby has trouble moving either or both of his eyes in all directions.
Your baby's eyes jiggle and cannot hold still.
Your baby's eyes are crossed most of the time, or one or both of your baby's eyes tend to turn in or out. (This is normal for the first few days of your baby's life, but tell the doctor if it lasts longer than that.)
One of your baby's pupils appears white.
Your baby's eyes seem sensitive to light and persistently drain or water.
If your baby was born prematurely – especially if he was very premature, had an infection, or needed treatment with oxygen – he's at greater risk for developing certain eye problems, including astigmatism (blurred vision), myopia (near-sightedness), retinopathy of prematurity (abnormal blood vessel growth that can lead to blindness), and strabismus (eye misalignment). Your baby's doctor will take his premature status into account when evaluating his eyes and making any necessary referrals.