What is retinopathy of prematurity?

The eye is often compared to a camera. The front of the eye contains a lens that focuses images on the inside of the back of the eye. This area, called the retina, is covered with special nerve cells that react to light.

Underneath the retina is a network of blood vessels. These blood vessels normally grow quickly in the last few weeks before a baby is born. If the baby is born prematurely, there can be a problem with this growth.

In some premature babies, the blood vessels grow into parts of the eye where they do not belong. This can cause scar tissue to form inside the eye. The scar tissue can damage the retina and cause a significant loss of vision. This condition is called retinopathy of prematurity.

Why do babies get retinopathy of prematurity?

Most infants who are born about 2 months or more prematurely or have a low weight at birth will have some amount of retinopathy of prematurity. Fortunately, the condition is often not severe, will not harm vision, and will go away without needing treatment. In some infants, however, the retinopathy of prematurity will develop very quickly and could cause a loss of vision or even blindness.

Over the years, doctors have identified several things that seem to make retinopathy of prematurity worse, such as supplying too much oxygen to premature babies. Avoiding those things has reduced the number of babies with severe retinopathy of prematurity, but it has not eliminated the condition.

There is no way to predict which babies will develop the more severe forms of retinopathy of prematurity. This is why it is very important for all babies born at 28 weeks or earlier, who weigh less than 1,500 grams (about 3 pounds, 5 ounces) at birth, or whose neonatologist deems them to be a high risk to be examined by an eye doctor. This exam often takes places 4 to 6 weeks after birth.

How does the doctor know whether an infant has retinopathy of prematurity?

The doctor will use a special instrument to look inside the eye at the retina. An important part of this examination is to find out how much of the retina of each eye may be affected by retinopathy of prematurity.

The doctor will grade the results of the examination on a standard scale of five stages. Stage 1 retinopathy of prematurity is the least severe form of the condition, and stage 5 is the most severe.

How is retinopathy of prematurity treated?

Only a doctor can recommend the right treatment for a baby with retinopathy of prematurity. The recommended treatment will depend on how severe the retinopathy is.

Stage 1 or 2 retinopathy usually does not require any treatment. Instead, the doctor will probably schedule frequent eye examinations to make sure that the baby's condition does not get worse. It is very important to keep these appointments, because the abnormal blood vessels could start growing at any time.

The doctor might recommend treatment for higher stages of retinopathy of prematurity. The only available treatments are surgical, and they are done under general anesthesia - that is, with the infant "asleep."

The procedures to treat retinopathy of prematurity include:

• Laser photocoagulation. This procedure is used to stop the abnormal growth of blood vessels through the retina. The surgeon focuses a laser beam onto a small spot on the retina where blood vessels are growing. The laser beam heats up that spot, creating a tiny burn in the blood vessels and stopping their growth. In most cases, the abnormal blood vessels will then get smaller and disappear.
• Cryoretinopexy. This procedure is also used to stop the growth of blood vessels. But in this treatment, an instrument called a cryoprobe is placed on the outside of the eye. The tip of this instrument gets very cold - so cold that it freezes the abnormal blood vessels growing inside the eye. This will also stop the growth of blood vessels and make them shrink away.
• Scleral buckling. The abnormal blood vessels and scar tissue damage the retina by pulling it away from the inside surface of the eyeball. This is called a retinal detachment, and it can cause a significant loss of vision. One way to reduce the tension on the retina is to push the wall of the eyeball inward. This can be done using something that looks like a rubber band. This elastic band is placed around the eyeball, and it pushes the inside surface of the eye up against the retina. This is called scleral buckling. The elastic band is removed when the eye outgrows it or when the retina becomes reattached to the inside surface of the eye.
• Vitrectomy. In eyes with a large amount of scar tissue and blood vessels, the surgeon might have to remove some of the gel-like fluid that fills most of the inside of the eye. This material is called the vitreous fluid, and the procedure to remove it is called a vitrectomy. In addition to removing the vitreous fluid, the surgeon will also remove the scar tissue that is pulling on the retina. This should help reduce the chances of a retinal detachment and prevent the loss of vision.

How successful is treatment for retinopathy of prematurity?

In the small number of infants who need treatment for retinopathy of prematurity, the treatments usually work well at preventing the loss of vision. The most important thing parents can do to help get the best result for their child is to keep all scheduled appointments and follow the doctor's advice after any treatment.