Retinopathy of Prematurity
What is Retinopathy of Prematurity?
Retinopathy of Prematurity (ROP) is a developmental disease of the eye that affects premature infants. When a baby is born, the retinal blood vessels have not completed their development. In patients with ROP, the blood vessels stop growing and new, abnormal blood vessels grow instead of normal retinal blood vessels. The developmental arrest and blood vessel maldevelopment may be temporary or permanent, minimal or severe. The most severe complication of this disease is bilateral blindness in early childhood.
Who gets ROP?
Almost all infants with advanced stages of ROP weighed less than 1,600 grams (about three pounds, eight ounces) at birth. Many required significant use of additional oxygen to stay alive. Some of these babies also suffered from severe infections, lung disease, anemia, hemorrhages in the brain, and a variety of other serious problems. Most babies with advanced ROP were born before 32 weeks of gestation. The smaller the baby or the more immature the retinal development, the more likely the infant is to develop complications of ROP which can lead to blindness. Infants under 1,000 grams (about two pounds, three ounces) are the most likely to develop severe ROP.
What are the phases of ROP?
The first early phase of ROP, called the acute phase, may start as early as five weeks after birth. The normal retinal blood vessel growth in these eyes has stopped. A fine white line separates the retina with normal blood vessels and the area of retina where blood vessels have not yet grown. If the disease continues, this line becomes larger, thicker and elevates into a ridge (see illustration). New blood vessels may grow from behind the ridge and sprout toward the front of the eye. These blood vessels may grow to cover a large area of the retina and are often accompanied by a significant amount of scar tissue. Over time, a scarring phase begins in which the blood vessels become bands of fibrous scar tissue that can contract and pull the retina away from the eyewall, causing a retinal detachment. If the disease continues, the scar tissue shortens just behind the lens and the detached retina becomes funnel shaped (see illustration). In these patients, blindness is common and the pupil is white (see illustration).
What is the treatment for ROP?
Patients with early stages of ROP need observation; most of these eyes will return to normal development. If the disease progresses, treatment is considered. A multicenter research trial funded by the National Eye Institute showed that destroying the undeveloped retina with freezing treatments (cryotherapy) stopped the progression of the disease in about 50 percent of infants. This reduced the number of retinal detachments in severely affected eyes from about 50 to 25 percent.
Recently, laser has become the standard treatment to destroy the non-developed retina. It appears that laser treatment is at least as effective as the cryotherapy and has a lower rate of complication. However, despite treatment, a significant group of patients continue to worsen. These patients may be helped with surgery for retinal detachment (scleral buckle or vitrectomy surgery).
How often should an ROP patient see an eye doctor?
Premature infants with ROP, both those requiring treatment and those who do not, have an increased rate of eye problems later in life. These include crossed eyes (strabismus), nearsightedness (myopia), glaucoma and retinal detachment. Therefore, even as an adult, ROP patients should have regular eye exams. If the disease is minimal, a yearly exam is adequate. More frequent exams may be needed for more severe disease.
What are the areas of active research in ROP?
There are many areas of ROP actively being studied. The use of supplemental oxygen to slow the development of ROP is one example. Although excess oxygen has been shown to constrict blood vessels and therefore plays a role in initiating the disease, oxygen supplementation may actually help prevent the growth of abnormal blood vessels after ROP has begun. Other future research includes early treatment procedures for active stages of the disease and the effect of light on the development of ROP..