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What is retinopathy of prematurity?

Today, doctors can help more premature babies than ever before clear their biggest hurdle: a successful birth. But that means they’re also seeing more babies with retinopathy of prematurity (ROP), a condition that affects the blood vessels in preemies’ eyes. In many children, ROP resolves on its own; however, infants with more severe forms of ROP face a serious risk of blindness.

  • Retinopathy of prematurity causes blood vessels to grow abnormally in the retina, the light-sensitive nerve tissue that lines the inside back wall of the eye.
  • Doctors don’t yet fully understand what causes ROP. But the more premature the baby and the lower the birth weight, the greater the risk for developing ROP.
  • How serious the ROP is depends on what part of the eye is affected (the zone); how far the disease has progressed (the stage); and whether the blood vessels themselves are markedly abnormal (plus disease).
  • About 90 percent of babies with ROP have a less serious form of the condition and improve without treatment.
  • Infants with more severe ROP may need laser therapy, cryotherapy (a freezing procedure) or, rarely, eye surgery.

How Children’s Hospital Boston approaches retinopathy of prematurity

At Children’s, experts in neonatal care and eye health team up to care for hundreds of infants with ROP each year. Our pediatric ophthalmologists work regularly with attending physicians in the Neonatal Intensive Care Unit (NICU) to screen babies for ROP and treat them when necessary. This strong partnership is a signature of the Children’s approach to safeguarding your child’s overall health.

In addition to offering the most up-to-date technology in detecting and treating ROP—such as a camera that can be used to take high-resolution digital pictures of infants’ retinas—Children’s is focusing on the future. Our physician-researchers are helping to identify which babies are at greatest risk for developing ROP, for example, and searching for ways to head off vision damage before it can start. They’re also examining the safety and effectiveness of promising new treatments, such as Avastin, that may change the way we treat ROP in the future.

Reviewed by Suzanne Johnston, MD
© Children’s Hospital Boston; posted in 2011

Retinopathy of Prematurity ROP | Symptoms & Causes

About half of the estimated 28,000 premature babies born each year in the United States have some degree of retinopathy of prematurity. The fact that it’s fairly common doesn’t make hearing the diagnosis any easier. But the more you know about ROP and your child’s eyes, the less stressful the experience is likely to be for you and your family.

Think of your child’s eyes as a camera. The front of the eye has the lens, which focuses on an image, and the pupil, which works like a camera shutter to control how much light enters the eye. At the back of the eye is the retina: Like film in the camera, this layer of nerve tissue is necessary to record the information that’s coming in and allow the brain to “develop” it into an image.

When children are born early, the blood vessels that feed the retina usually haven’t finished growing. ROP occurs when these vessels actually stop growing for a time, then begin growing abnormally and randomly. The new vessels are fragile and can leak, leaving the retina scarred. In the worst-case scenario, the retina detaches (tears away from the back wall of the eye) and puts the baby at high risk of becoming blind.

To better understand your child’s condition, it helps to know the three most common ways doctors describe ROP: by zone, by stage and by the presence or absence of “plus disease.”

  • The zone indicates where the disease is located. Zone 1 is a small area at the heart of the retina (surrounding the central visual area, including the optic nerve); Zone 2 covers the middle of the retina; and Zone 3 runs along the retina’s outer edge. The lower the zone number, the more serious the ROP.
  • The stage describes how far the disease has progressed. Stage 1 has mildly abnormal vessel growth, while Stage 5 is “end stage” — the abnormal growth and scarring are so severe that the retina detaches.
  • Plus disease means that the blood vessels themselves are abnormally twisted and enlarged. A finding of plus disease or its warning signs (known as pre-plus disease) is a serious one, and has become very important in helping doctors decide when treatment is needed.


Who is at risk?

Premature babies are the number-one risk group for retinopathy of prematurity. In general, the smaller and more premature the infant, the more likely he or she is to develop ROP, and the more likely to need treatment.


Babies considered most at risk for ROP have:

  • a gestational age of 30 weeks or less, compared with 38 to 42 weeks for a full-term infant (“gestational age” means the amount of time since the baby was conceived)
  • a birth weight of 1,500 grams (3.3 pounds) or less, which is 2,000 grams (about 4.4 pounds) less than for a typical full-term infant

Other possible risk factors for ROP include:

  • anemia
  • infection
  • transfusions
  • breathing difficulties
  • heart disease
  • ethnicity (ROP occurs slightly more often in Caucasian children)

ROP has also been linked to supplemental oxygen, something often given to preemies. But excessive oxygen levels are largely a thing of the past, thanks to modern-day improvements in monitoring systems.

Causes of retinopathy of prematurity

Researchers are still working to understand the mechanism behind retinopathy of prematurity — that is, what causes the retinal vessels in many premature babies’ eyes stop growing, then begin growing abnormally.

Studies led by Children’s Hospital Boston ophthalmologist Lois Smith, MD, PhD, suggest that ROP might be caused by the early cutoff of chemicals that babies receive from their mother in the womb, including insulin-like growth factor I (IGF-I) and vascular endothelial growth factor (VEGF). However, it’s possible there are other chemicals are at play, and research is ongoing.

Signs and symptoms

Many of the signs of retinopathy of prematurity happen deep inside the eye, which means you won’t be able to see them just by looking at your child. Only an ophthalmologist (a doctor who specializes in caring for eyes) who is trained to recognize and treat ROP can spot these signs, using special instruments to examine your child’s retina.

The American Academy of Pediatrics has set ROP screening guidelines for all newborn intensive care units, and the vast majority of infants with ROP are identified through those exams.

An infant with severe ROP might develop visible complications, such as nystagmus (abnormal eye movements) and leukocoria (white pupils). However, these are also general signs of vision trouble — if your child has any of these, you should see an ophthalmologist right away.


Q: Do all babies born prematurely get ROP?

A: No. In about one out of two preemies, the blood vessels continue growing normally (although finishing the job a few weeks later than the original due date).

Q: How common is severe ROP?

A: Of the estimated 14,000 premature babies born with ROP each year in the U.S., about 1,100 to 1,500 (about 10 percent) develop disease severe enough to require medical treatment. About 400-600 infants become legally blind from ROP.

Q: Can ROP get better or heal on its own?

A: Yes. This is called “regression” of the disease, and usually happens in mild ROP (Stage 1 and 2). It can also happen in more severe ROP—but even after the abnormal blood vessels go away, there may be retinal scarring that needs to be watched closely.

Q: Does ROP always happen in both eyes?

A: Yes and no: While this disease typically affects both eyes, occasionally it’s more severe in one eye than the other. Rarely, doctors may need to treat just treat one eye.

Q: How accurate is ROP screening?

A: Retinal exams by a pediatric ophthalmologist can detect the disease with about 99 percent accuracy, according to the American Academy of Pediatrics, which sets the screening guidelines.

Q: Does a diagnosis of ROP mean my baby has to stay in the hospital longer?

A: ROP screening doesn’t begin until a premature infant is four to nine weeks old, which means your baby might even be discharged from the NICU before he’s due for his first screening exam. If he’s diagnosed with ROP while still in the NICU, though, you’ll likely be able to take him home on schedule. Your doctors will watch how his ROP progresses—and decide when to treat it—through follow-up exams.

Q: How is ROP treated?

A: Laser therapy or cryotherapy (freezing) can help slow or reverse the abnormal growth of blood vessels; in the most severe stages of ROP, eye surgery may be needed. There are no FDA-approved medications to treat ROP, though some drugs are now being studied.

Q: What are the possible complications of ROP?
About 10 percent of infants with retinopathy of prematurity will need medical treatment, such as laser therapy (photocoagulation). Not all babies respond to treatment, though, and if the ROP continues to worsen it can cause such complications as:

  • scarring and/or dragging of the retina
  • retinal detachment
  • bleeding inside the eye (vitreous hemorrhage)
  • cataracts
  • blindness

The other 90 percent of infants have a mild form of ROP, which usually resolves itself without treatment in the first few months of life. However, these children may be at higher risk for developing certain eye problems later in life, such as myopia (nearsightedness), strabismus (crossed eyes), amblyopia (lazy eye) and glaucoma.

Q: Can ROP be prevented?
Since the exact cause of retinopathy of prematurity isn’t known, the best prevention is prenatal care to reduce the likelihood of premature birth.

Although doctors can’t prevent ROP, they can help prevent its most harmful effects through careful screening and treatment.

Retinopathy of Prematurity ROP | Testing & Diagnosis

If your child is born prematurely, there’s a 50-50 chance he will develop some degree of retinopathy of prematurity. Since the disease has no outward symptoms, you can’t “see” it — and neither can the doctors and nurses who work in the neonatal intensive care unit. That’s why infants at risk for ROP are routinely screened by pediatric ophthalmologists using special equipment.

In 2006, the American Academy of Pediatrics revised its guidelines for ROP screening. They include:

  • All infants with a birth weight of less than 1,500 grams (about 3.3 pounds) or a gestational age of 30 weeks or less should be screened by an ophthalmologist.
  • Infants with a birth weight of 1,500 and 2,000 grams or a gestational age of more than 30 weeks should be screened if other health troubles put them at high risk for ROP.
  • The first exam should occur four to nine weeks after birth, depending on how premature the baby is.
  • If the exam shows the retina is fully “vascularized” (its blood vessels have finished growing normally), no follow-up is needed.
  • If there are signs of ROP, however, the ophthalmologist will set follow-up exams to monitor the condition and determine when treatment is needed.

The screening exam may take place at your child’s bedside in the NICU or, if he’s already been discharged, at the ophthalmologist’s office. Here’s what’s typically involved:

  • dilating eye drops, to enlarge the pupil (giving the doctor a bigger “window” into the eye)
  • an eyelid speculum, which holds the eyelids open
  • a scleral depressor, which helps move the eye into different positions so the entire retina can be checked
  • an indirect ophthalmoscope, which has a special lens that sends a bright light into the eye, enabling the doctor to examine the retina

Doctors are also making increasing use of an innovative device called the RetCam, a special camera that takes high-resolution digital pictures of the retina. This provides detailed images that can be compared from one exam to the next to help track the health of your child’s eyes over time.

Questions to ask your doctor

You and your family are key players in your child’s medical care. It’s important that you share your observations and ideas with your child’s health care provider and that you understand your provider’s recommendations.

If your child is diagnosed with ROP, you probably already have some ideas and questions on your mind. But during the appointment, it can be easy to forget the questions you wanted to ask. It’s often helpful to jot them down ahead of time so that you can leave the appointment feeling that you have the information you need.

Some of the questions you may want to ask include:

  • How severe is my child’s ROP?
  • How frequently do I need to bring him in for follow-ups?
  • Will he require medical treatment?
  • What is the treatment success rate?
  • Does the treatment have any complications?
  • What is the long-term outlook for my child?

Retinopathy of Prematurity ROP | Treatments

No parent wants his or her child to be unwell, and hearing that your baby is having trouble with something as vital as his eyes can be especially difficult to hear. But at Children's, we view the diagnosis as a starting point: With early detection of ROP, we can closely follow the progress of the disease to determine the right time to begin treatment, if needed, for the best results for your baby's eyes.

If your child has mild retinopathy of prematurity (Stage 1 or 2), the abnormal retinal blood vessels usually heal on their own sometime in the first four months of life. But if the ROP worsens, he may need treatment.

The goal of treatment is to halt the abnormal blood vessel growth in the eyes and limit its harmful effects, like scarring or retinal detachment.

Photocoagulation (laser therapy)

Photocoagulation is the first line of defense against ROP. The setup is much like a retinal exam, except your child will be given local or general anesthesia. The ophthalmologist uses a diode laser mounted on the indirect ophthalmoscope to make tiny “burns” in the periphery of the retina, to prevent further growth of abnormal blood vessels.

Your child's doctor will set follow-up exams — usually every one to two weeks — to see how the eyes are responding to the laser treatment. If the ROP continues to worsen, your child may need additional laser treatments or possibly eye surgery.

Cryopexy (cryotherapy)

Formerly the procedure of choice for treating ROP, cryopexy uses a penlike instrument called a cryoprobe to freeze parts of the retina's periphery through the outer wall of the eye. Though it's largely been replaced by laser therapy, cryopexy is useful when the retina can't be fully seen (because of a hemorrhage, for example).

Because both photocoagulation and cryopexy destroy part of the retina's periphery, your child may lose some of his side vision with these treatments. However, the procedure aims to save his “central vision”—the most important part of sight — which is necessary for things like reading and driving.

Eye surgery

If your child's retinal becomes partly or completely detached — Stage 4 or 5 — your doctor may refer him to a retinal surgeon for treatment, usually scleral buckling or vitrectomy.

  • Scleral buckling involves placing a silicone band around the eye and tightening it until the retina is close enough to the wall to reattach itself. The band, called a scleral buckle, can be left in place to protect the eye for months, or sometimes years.
  • Vitrectomy involves removing the vitreous (the gel-like substance that fills the back of the eye) and replacing it with saline solution or oil. The scar tissue on the retina can then be peeled back or cut away, allowing the retina to flatten back down against the wall of the eye.

Useful medical terms

Amblyopia: Poor vision in one eye; sometimes called lazy eye.

Cryopexy: A treatment for ROP that freezes tissue along the retina's periphery; also called cryotherapy.

Gestational age: The length of time between a baby's conception and birth.

Macula: Part of the retina directly behind the lens, which is responsible for central vision.

Myopia: Nearsightedness.

Photocoagulation: A treatment that uses a laser to “burn” tissue along the retina's periphery; also called laser therapy.

Plus disease: A condition in which retinal blood vessels become abnormally twisted and enlarged.

Regression: A return to a previous state; in ROP, this describes the diminishment or vanishing of abnormal blood vessels.

Retina: The light-sensitive inner lining of the eye wall, responsible for capturing visual information and sending it to the brain.

Retinal detachment: When part or all of the retina comes away from the back wall of the eye.

Sclera: The outer layer of the eye; the "white" of the eye.

Scleral buckling: A surgical procedure in which a silicone band is placed around the eye and tightened until the retina is close enough to the wall to reattach itself.

Strabismus: The abnormal alignment of one or both eyes; sometimes called crossed eyes.

Vitrectomy: A surgical procedure in which the vitreous is removed from the eye so that the retina can be reattached.

Vitreous: The gel-like substance that fills the back of the eye and gives the eye its shape.

Long-term outlook

If your baby is diagnosed with prematurity of retinopathy, you may understandably be worried about what it means for the future. Will my child be able to lead a normal life? is a question that many parents in your situation ask. And for the vast majority of babies with ROP, the answer is yes.

The long-term outlook for your child hinges on two factors:

  • early detection and treatment
  • the severity of the disease — Stages 1 and 2 are considered mild; Stages 3-5 are increasingly serious

If your child has Stage 1 or 2 ROP, the abnormal blood vessels will often shrink or go away on their own and there's no loss of vision. Down the road, your child may face an increased risk for eye problems like nearsightedness, but in many cases these conditions can be treated or controlled.

Sometimes, though, Stage 1 or 2 ROP will worsen to Stage 3 or higher. Here, the outlook is more guarded. Bleeding and scar tissue may lead to distortion or detachment of the retina, which — even with treatment — can cause moderate to severe vision loss, or even blindness.

Coping and support

We understand that you may have a lot of questions when your child is diagnosed with retinopathy of prematurity. Is it dangerous? Will it affect my child long term? What do we do next? We've tried to provide some answers to those questions here, and our experts can help explain your child's condition more fully. If you have additional questions while your child is being treated at Boston Children's Hospital, we may be able to put you in touch with other Children's families who have dealt with ROP.

Children's also has several resources designed to give your family comfort, support and guidance:

  • Children's Center for Families is dedicated to helping families locate the information and resources they need to better understand their child's particular condition and take part in their care. All patients, families and health professionals are welcome to use the Center's services at no extra cost. The center is open Monday through Friday from 8 a.m. to 7 p.m., and on Saturdays from 9 a.m. to 1 p.m. Please call 617-355-6279 for more information.
  • You can learn more about topics in neonatal intensive care at a monthly drop-in group for local NICU parents hosted at Brigham and Women's Hospital, located near Children's in the Longwood Medical Area. The interactive forum features speakers—including Children's nurses and physicians—presenting information on a particular NICU topic.

Online resources

There are a number of outside groups that provide additional help for families facing retinopathy of prematurity. Two to try:

  • The Association for Retinopathy of Prematurity and Related Diseases ( Founded in 1990 by physicians and volunteers, ROPARD funds research to understand, treat and prevent retinopathy of prematurity and related retinal diseases. It publishes a biannual newsletter, and its website includes tips and recommendations for parents of children who have suffered ROP-related vision loss.
  • National Eye Institute ( Overseen by the National Institutes of Health, the NEI conducts and supports research on eye diseases and vision disorders. It offers a searchable database of clinical studies, as well as a number of free publications written for vision patients and their families.

Retinopathy of Prematurity ROP | Programs & Services