Early Eye Development

A baby’s eyes start developing early in pregnancy. Since a pregnancy is timed from the date of your previous period, subtract two weeks from the pregnancy length to get the baby’s age.

First Trimester:
In the third week of pregnancy the embryo implants itself in the uterus. At this point it is called a zygote. The placenta is just beginning to form and your pregnancy test may be positive. By the end of your first month, the zygote is called an embryo and has now grown to be 1/25 inch long.

In the second month its heart will form and start to beat although an ultrasound exam is the only way to hear it. Now there is blood circulation – the first organ system to function.

In the sixth and seventh weeks, your baby grows to about 1/4 inch long and facial features are starting to appear, including two eye sockets. There are buds for arms and legs but there is also still a tail. This embryo cannot yet be distinguished from many mammal embryos.

The eyes move to the front of the face in the ninth week and transparent eyelids begin to form. Although the embryo is only 7/8 inch long and weighs less than an aspirin, all its essential organs have started to form.

Second Trimester:
By the 14th week the embryo is called a fetus and has a head nearly half its total size with a well-formed face. It is about three inches long and weighs an ounce. The eyelids are no longer transparent and now become fused shut until early in the third trimester. This protects the developing eye structures. By the 16th week the eyes are starting to become light-sensitive, although they are not actually seeing any light at this stage.

By the 19th or 20th week the fetus is about eight inches long and has eyebrows and eyelashes. You can feel it moving and with a stethoscope can hear its heartbeat. By the time it is 22 weeks old (24th week of pregnancy), all the eye elements have developed and it has grown to about eleven inches and almost two pounds.

Third Trimester:
In the first month of the third trimester, the eyes start to open and close and the fetus reaches about 15 inches and nearly three pounds. The brain is developing quickly and the nervous system can control some of the body functions. It is thought the baby can now recognize its mother’s voice.

By the 28th week, the baby’s eyes have a color, but at birth they will typically look dark blue-gray. Only if they are to be black or dark brown will they look that color at birth. When the ninth month begins (week 33) the pupils start to constrict and dilate and the eyes can see light. There is no light in the uterus, but babies born about four weeks premature can see light.

The Baby’s Eyes at Birth:
The eyes of a full-term newborn are complete but only about 75 percent of adult size. They have color vision and visual acuity is about 20/400 – very myopic. But they can see a parent’s face when being held, and will often gaze intently at that face.

A pediatrician will check a newborn’s eyes for any infection or malformation. Sometimes a baby is born with cataracts or glaucoma. If necessary, an ophthalmologist can do a full eye exam with dilation even at this young age.
A new baby does not track moving objects until six to eight weeks of age and may have a cross-eyed look until then. Babies must develop control over the eye muscles. The eyes may not be aligned at first, that is, not working together—a condition called strabismus. But by about four months of age, the eyes will normally align properly and the baby will have three-dimensional vision.

A new baby may not produce any tears when it cries but after four to five months that function will be established. In the meantime, they have a natural film over the eyes that protects them from dust or fluff.

The eyes continue to grow and develop until the age of about two years, when they are fully mature. You can have your baby’s vision tested at any age if you start to wonder if he or she is nearsighted, farsighted or astigmatic.