Rods help us see in dim light, and cones detect color. The layered structure at the back of the eye (retina) contains millions of light-sensitive cells called rods and cones. The shape of the lens changes to focus on objects that are close or far away. In the dark, the iris shrinks and the pupil gets bigger, allowing in as much light as possible.Īs light enters the eye, it hits the lens, a structure behind the pupil that directs the light toward the back of the eye. In bright light, the iris expands and the pupil gets smaller, restricting the amount of light entering the eye. The dark spot in the center of the eye (pupil) and the pigmented part that surrounds the pupil (iris) determine the amount of light that's let in. The cornea is the clear "window" at the front of the eye, which lets in light. To understand your baby's vision, it's helpful to know the parts of the eye and how we see: By 31 weeks, the pupils can constrict, dilate, and detect light. Your baby's eyes first open around 27 weeks of pregnancy, at the end of your second trimester. This means that your baby's tear production doesn't reach full potential until they're a few weeks old. And here's an interesting fact: Although your baby's tear ducts start developing at about 8 weeks, they won't be completely formed until a few weeks after birth (and it may take even longer for preemies). As these structures enlarge, they remain connected to the brain by a stalk that will eventually house the main optic nerve.Īt about 7 weeks, the main parts of the eye that enable sight – the cornea, iris, pupil, lens, and retina – start developing, and they're almost fully formed just a few weeks later.īy about 10 weeks, your baby has eyelids, though they remain closed. Beginning at 6 weeks of pregnancy, these growths start to fold inward and form two cup-like structures. Your baby's eyes start out as two tiny outgrowths from the developing brain. When do babies' eyes develop in the womb?
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