Retinopathy of Prematurity (ROP)

What is ROP?

Retinopathy of prematurity (ROP) is a potentially blinding disease caused by abnormal development of retinal blood vessels in premature infants.

ROP is a problem with the way the blood vessels develop on the surface of the retina. (The retina is the layer at the back of the eye that is like a film in a camera - see figure 1.) When a baby is born prematurely these blood vessels are immature like the rest of the baby. In most premature babies the retinal blood vessels grow properly. In some premature infants the blood vessels start to grow the wrong way. Instead of branching like a tree the vessels link up side to side and in some cases grow away from the retina towards the centre of the eye.

Figure 1. Major parts of the eye.

Stages of ROP

The severity of ROP is graded from stage one to stage five. Stage one is the mildest and stage five the most severe.

Stage 1: A fine, thin demarcation line appears between the vascular and avascular retina.

Stage 2: The line widens and becomes a broad, thick ridge.

Stage 3: The growth of abnormal new vessels gives the ridge a pink velvety appearance and a ragged border.

Stage 4: Bleeding and scar tissue cause partial retinal detachment beginning at the ridge .

Stage 5: This stage is a total retinal detachment in the shape of a funnel.

Plus disease: it is part of the subclassification of stages characterised by vascular tortuosity and venous engorgement. Its presence is an ominous sign.

APROP: Aggressive posterior ROP is a severe form of disease which can rapidly progress to retinal detachment without passing through classic stages and hence needs an emergency treatment.

Why do premature babies get ROP?

Birth weight and gestational age are the most important risk factors for development of severe ROP. Other factors that are associated with the presence of ROP include anemia, poor weight gain, blood transfusion, breathing difficulties, sepsis and the overall health of the infant.

ROP has been linked to excessive use of oxygen. However, now the supply of oxygen to premature babies is very closely monitored and the amount of oxygen given to your baby is very carefully calculated and controlled.

It is well known that the sicker and smaller a baby is the more likely it is that ROP will develop.

How will I know if my baby is getting ROP?

We cannot predict which babies will develop ROP. All babies weighing less than 2000 grams at birth will have regular eye examinations after their gestational age reaches 30 to 31 weeks. These examinations are undertaken by an eye specialist known as a Retina Specialist. To look at the back of a baby's eyes the pupil (black circle in the middle of the coloured part at the front of the eye) needs to be dilated (see figure 2). Eye drops are used to dilate the pupils. The examination only takes a few minutes.

Figure 2. Eye drops make the pupil larger so the retina can be examined.

If my baby has ROP, what happens?

In most babies ROP is mild and over a period of weeks the ROP gradually disappears.

The ophthalmologist will check your baby's eyes every one or two weeks and you will be told the result of each examination.

Can ROP be treated?

Yes, but remember few babies develop ROP that is bad enough to need treatment.
About 5 % of babies checked for ROP actually need treatment.
Mild ROP might not need treatment as it generally goes away by itself.
Threshold disease (severe stage three or more ROP) will need treatment.
If your baby develops threshold ROP, treatment options will be discussed with you.
The treatment is generally done with laser or injecting medicine in the eye and in 90% of babies needing treatment the ROP disappears and sight is preserved.
If your baby may need treatment more information will be given to you and you can discuss the situation with the paediatricians and Retina Specialist caring for your baby.

Illustration

Right and Left Eye with ROP and Plus disease ( before and after treatment with Anti-VEGF injection)

Left eye with ROP treated with Laser ( laser marks shown with yellow arrows)

Aggressive Posterior Retinopathy of Prematurity (APROP)