The retina is the light-sensitive lining of the eye. In unborn babies, as the rest of the fetus is developing normally, so is the retina. But sometimes in premature babies, this lining can develop abnormally and result in a condition called retinopathy of prematurity (ROP). It generally occurs in both eyes, but one eye may be worse than the other. Having ROP in only one eye is very rare.
Infants are not born with ROP. Rather they are born with an immature retina, one with incomplete development of the vessels that supply blood to the retina. Not all premature infants develop retinopathy of prematurity. And even for those infants born with this condition, it often resolves without treatment. But if ROP worsens, the condition must be treated. That’s because ROP can worsen into a potentially blinding eye problem, one which each year results in the blindness of about 500 infants in the United States alone.
Additional Complications of ROP
For most infants with mild retinopathy of prematurity (stages 1 to mild 3), the ROP will resolve spontaneously with no remaining scar tissue. But if the disease should progress, some infants with ROP may suffer further complications later in life. These complications may include:
Strabismus and Amblyopia
Strabismus (crossed eyes) and amblyopia (lazy vision in one eye) occur more often in infants with even the mildest stages of regressed ROP than in premature infants who do not develop ROP. This may require eye muscle surgery for strabismus and patching for amblyopia.
This near-sightedness may occur with the mildest forms of regressed ROP. The greater the amount of ROP scar tissue remaining, the more severe the myopia. But such near-sightedness can be corrected with glasses.
The increased pressure in eyes with regressed or treated ROP may cause pain and damage vision. Laser treatment or surgery may be necessary to help the eye drain off the build-up of watery fluid (aqueous fluid) that causes increased pressure.
Late-onset Retinal Detachment
In rare cases, late-onset retinal detachment may occur in the mid-teens or early adulthood. As the eye grows or the vitreous gel shrinks, ROP scar tissue can pull holes in the retina. This usually requires surgery to repair. It’s important that anyone who has had ROP see a retinal specialist or pediatric ophthalmologist at least once a year during childhood and the early adult years.
Who is at risk?
There are two critical factors for predicting which children are most likely to develop retinopathy of prematurity (ROP):
- Birth weight of less than 3 lbs., 5 oz.
- Birth after less than 32 weeks of pregnancy.
Infants weighing less than 2 lbs., 3 oz. at birth and born after a pregnancy of 23 to 28 weeks have a particularly high chance of developing retinopathy of prematurity. The lower the birth weight and gestational age, the higher the risk and severity of ROP.
There are three options for treating ROP:
This has been the standard treatment for ROP since the late 1980s. In half the cases of infants with threshold ROP, cryotherapy prevents progression to retinal detachment and possible blindness. A cold probe applied to the outside of the eye freezes the abnormal retina, eliminating its demand for oxygen. The abnormal blood vessels disappear and progression of scar tissue stops.
For more than 20 years, lasers have been used to treat eye disorders in adults. But recent technical advances now make it possible to apply this treatment to newborn infants. The indirect ophthalmoscope – the same instrument used to examine the infant’s eye – is also used to deliver the laser beam into the eye. If the doctor can see the abnormal retina, the laser can treat it – with fewer side effects.
If cryotherapy or laser treatment for advanced or Stage III ROP is unsuccessful in preventing retinal detachment, there are still some surgical options. If the detachment is shallow (not a lot of space between the retina and the eye wall), a technique called scleral buckling may prove effective. This involves placing a silicone “belt” around the outside of the eye and tightening it until the retina is close enough to the wall to reattach itself. If scleral buckling is impossible or unsuccessful, a vitrectomy can be performed. During this major procedure, tiny holes are made in the wall of the eye to allow access to the center. The vitreous gel is then removed from the eye. The retina is flattened under a bubble of air. Laser treatment is applied to seal around the leaks.
Stages of ROP
If an infant develops ROP, the condition will appear when the infant is between five and 15 weeks old. In many cases, the disease disappears as the retinal blood supply develops normally. But if ROP does not resolve itself, the disease can progress to retinal detachment and blindness.