The blood vessels of the retina begin to develop three months after conception and complete their development at the time of normal birth. When an infant is born very prematurely, the infant's eye development will be disrupted.

In infants who develop retinopathy of prematurity (ROP), the vessels grow abnormally from the retina into the normally clear gel that fills the back of the eye. Here, without support, the vessels are fragile and often hemorrhage into the eye.

This is followed by scar tissue development which pulls the retina loose from the inner surface of the eye and draws it toward the center of the globe, producing a retinal detachment. This can reduce vision or, if severe, result in complete blindness.

Many premature infants develop transient and mild abnormal retinal blood vessel growth that converts to normal growth without treatment. Only approximately 1 out of 10 infants with early changes will progress to more severe retinal disease.

In the past, excess use of oxygen to treat premature babies stimulated abnormal vessel growth. Currently, oxygen can be easily and accurately monitored, and this is rare.

Today, the risk of developing ROP is proportional to the severity of prematurity. Typically all babies less than 32-34 weeks gestation are screened for the condition. However, only the smallest premature babies, no matter what their gestational age, have the highest risk.

Subtle retinal changes of ROP are visible only by ophthalmoscopic examination and cannot be seen by the parents. All premature infants are screened and followed routinely. Results of severe ROP may produce some of the following signs:

• white pupils (leukocoria)
• abnormal eye movements (nystagmus)
• crossed eyes (strabismus)
• severe nearsightedness (myopia)

Retinopathy of prematurity can be diagnosed during examination by an ophthalmologist. Since there are few signs that ROP is developing, it is specially important to screen babies less than 32 weeks gestation.

Examination is painless, requiring eye drops and then examination. Follow-up examinations are conducted in approximately 2 week intervals. Special tests are usually not required.

Treatment may include:

• Cryotherapy (freezing therapy).
• Laser therapy (which is now used more commonly than cryotherapy) may be used to treat areas of retina that have not had normal development of blood vessels. To be effective, this must be done before scarring and detachment occurs.
• Surgery to reattach the retina if detachment develops.
• Children with milder changes may need special low vision support as they grow.

In the early stages of ROP with proper screening, treatment is usually limited to laser therapy and close follow-up. Fortunately, laser therapy can be performed in the nursery using portable equipment.

• blindness
• severe myopia (near-sightedness)
• Most children with severe vision loss from retinopathy of prematurity have other complications of prematurity and require a multi-disciplinary approach to rehabilitation

This condition is discovered in the hospital setting during evaluation of the premature infant. If your child has had ROP and appears to be having increased visual difficulties, contact your health care provider.

The incidence of ROP in moderately premature infants has decreased dramatically with better care in the neonatal intensive care unit. Ironically, however, this has led to high rates of survival of very premature infants who would have had little chance of survival in the past.

Since these very premature infants are at the highest risk of developing ROP, the condition may actually be becoming more common again. The most effective prevention of retinopathy of prematurity is prevention of premature birth.