Retinopatía del prematuro

What is retinopathy of prematurity?

Retinopathy of prematurity (ROP) is an eye problem which can occur in babies who were born too early (premature babies). It particularly affects babies who were born before the 32nd week of pregnancy, or who weighed less than 1500 g at birth. The earlier the baby is born, the higher the risk. ROP is found in most babies (four out of five) who weighed less than 1000 g at birth.

In many babies it is a mild condition and treatment is not always needed. In others, it can be very severe.

All organs of the body develop as the baby grows in the womb. The eye normally develops relatively late on in pregnancy. In particular the blood vessels of the back of the eye (the retina) are formed quite late in the baby's development. So if the baby is born early, these blood vessels may not have yet fully formed. Outside the womb, the differing oxygen levels may cause abnormal blood vessels to form. These can bleed, causing scarring and in some cases causing the retina to become separated from the back of the eye (detached). The retina is essential for eyesight, so damage to it can cause loss of vision.

Sección transversal del ojo

There are no signs early on, so all premature babies are regularly checked for this condition. All babies born before 32 weeks will have regular eye screening tests. These are carried out every 1-2 weeks by an eye specialist doctor (ophthalmologist). The specialist has to look right into the back of the baby's eye so this is a procedure which is a bit of a challenge. It may be uncomfortable for the baby, so a little sugar water may be used to help relieve discomfort.

Some drops will be put into the baby's eyes to open up the middle black part (pupil) so that the doctor can look through it to the retina behind. The eyelids will be held open with an eye speculum. An instrument called an ophthalmoscope, usually positioned on the doctor's head, is used to see the back of the eye. Another instrument (indentor) may be used to press slightly on the eyeball in order to see the retina better.

The doctor can then assess how severe the problem is. Stage 0 means there is no ROP found. There are five stages of ROP if it is present, based on this examination. Stage 1 is the mildest and Stage 5 is the most severe, where the retina has completely separated (detached) from the back of the eyeball. It will also be noted which sections (zones) of the retina are affected. The terms 'plus' and 'pre-plus' may also be used, which describe further irregularities of the blood vessels. All this information helps the doctors to know what treatment is needed.

Mild ROP does not need treatment, as it will usually resolve by itself.

Treatment with laser (photocoagulation) is most often used. This destroys any abnormal parts of the retina. If this is not available a freezing treatment (cryotherapy) is sometimes used instead.

Another treatment option is injections into the eye. The injection used is an anti-vascular endothelial growth factor (anti-VEGF). This is a treatment that helps to halt the abnormal growth of blood vessels. There are several anti-VEGF medicines, including bevacizumab, ranibizumab and pegaptanib. Although used for other conditions, these treatments are not specifically licensed for ROP. Studies are still going on to establish how effective this treatment is.

Occasionally an operation is needed - for example, if the retina has become detached. This is a risky option as the structures of the eye are so fragile at this stage of life.

If treatment for ROP is needed, regular eye checks are then necessary for at least five years.

This depends on how severe the ROP is. Babies with Stage 1 and Stage 2 ROP should not have any long-term problems with their eyesight as a result of this condition. Without treatment, babies with more severe ROP are more likely to have poor vision or total loss of vision. Treatment improves this outlook (prognosis) and fewer babies will have total loss of vision as a result. However, treatment does involve destroying some of the retina, so treated babies may not have such good vision in the long term as those who did not have ROP. Babies with ROP may have a higher chance of other eyesight problems in later life, such as squints, cataratas o glaucoma. Also in some cases there may be complications of treatment, such as bleeding into the eye, which can in themselves cause problems with vision.

Your specialist will be able to explain the outlook in your baby's individual case.