Retinopathy of Prematurity

What is retinopathy of prematurity?

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

Beneath the retina lies a network of blood vessels. These vessels normally grow rapidly in the last few weeks before a baby is born. If a baby arrives prematurely, this growth can be disrupted.

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

Why do babies develop retinopathy of prematurity?

Most infants born around two months or more early, or with a low birth weight, will have some degree of retinopathy of prematurity. Fortunately, the condition is often not serious: it does no harm to vision and settles without any need for treatment. In some infants, however, retinopathy of prematurity progresses very quickly and can cause vision loss or even blindness.

Over the years, doctors have identified a number of factors that appear to worsen retinopathy of prematurity, such as giving premature babies excess oxygen. Avoiding these factors has reduced the number of babies with severe disease, but has not eliminated the condition.

There is no way to predict which babies will develop the most severe forms of retinopathy of prematurity. That is why it is so important that every baby born at 32 weeks or earlier, weighing less than 1,500 grams at birth, or considered high-risk by their neonatologist, is examined by a paediatric ophthalmologist.

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

The doctor uses a special instrument to look into the eye and examine the retina. An important part of this examination is determining how much of the retina of each eye is affected by the condition.

The doctor grades the findings on a standard five-stage scale. Stage 1 is the mildest form of retinopathy of prematurity; stage 5 is the most severe.

How is retinopathy of prematurity treated?

Only a paediatric ophthalmologist 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 needs no treatment. Instead, the doctor will most likely schedule frequent eye examinations to make sure the baby’s condition is not worsening. Keeping these appointments is very important, because abnormal blood vessels can begin to grow at any time.

For the higher stages of retinopathy of prematurity, the doctor may recommend treatment. The only available treatments are laser or surgical procedures, performed under general anaesthesia.

Procedures used to treat retinopathy of prematurity include:

Laser photocoagulation

This procedure is used to stop abnormal blood vessels growing across the retina. The surgeon focuses a laser beam onto a small spot on the retina where the vessels are growing. The beam heats that spot, creating a tiny burn in the blood vessels and halting their growth. In most cases, the abnormal vessels then shrink and disappear.

Intravitreal Anti-VEGF injection (Avastin)

When intravitreal bevacizumab (Avastin) came into common use for treating neovascular age-related macular degeneration (AMD) and diabetic retinopathy, researchers considered that bevacizumab (Avastin) might also benefit patients with retinopathy of prematurity. It is now accepted that intravitreal injection of bevacizumab is effective in promoting the resolution of retinopathy of prematurity requiring treatment; this regression is often quite dramatic, occurring within the first 24 to 48 hours after injection. Several case series have reported resolution of retinopathy of prematurity in patients treated with bevacizumab (Avastin) alone or in combination with laser photocoagulation.

Vitrectomy

In eyes with extensive scar tissue and abnormal vessels, the surgeon may need to remove part of the gel-like fluid that fills most of the inside of the eye. This material is called the vitreous, and the procedure to remove it is called a vitrectomy. As well as removing the vitreous, the surgeon removes the scar tissue that is pulling on the retina. This should reduce the chance of retinal detachment and help prevent 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 loss of vision. The most important things parents can do to secure the best outcome for their child are to keep every scheduled appointment and to follow the paediatric ophthalmologist’s advice after any treatment.