Retinopathy of prematurity (ROP) is abnormal blood vessel development in the retina of the eye in a premature infant.

The blood vessels of the retina begin to develop 3 months after conception and complete their development at the time of normal birth. If an infant is born very prematurely, eye development can be disrupted. The vessels may stop growing or grow abnormally from the retina into the normally clear gel that fills the back of the eye. The vessels are fragile and can leak, causing bleeding in the eye.

Scar tissue may develop and pull the retina loose from the inner surface of the eye. In severe cases, this can result in vision loss.

In the past, routine use of excess oxygen to treat premature babies stimulated abnormal vessel growth. Currently, oxygen can be easily and accurately monitored, so this problem is rare.

Today, the risk of developing ROP depends on the degree of prematurity. Generally, the smallest and sickest premature babies have the highest risk.

Typically all babies younger than 30 weeks gestation or weighing fewer than 3 pounds at birth are screened for the condition. Certain high-risk babies who weigh 3 - 4.5 pounds or who are born after 30 weeks should also be screened.

In addition to prematurity, other risks factors may include:

• Brief stop in breathing (apnea)
• Heart disease
• High carbon dioxide (CO2) in the blood
• Infection
• Low blood acidity (pH)
• Low blood oxygen
• Respiratory distress
• Slow heart rate (bradycardia)
• Transfusions

The rate of ROP in moderately premature infants has decreased dramatically with better care in the neonatal intensive care unit. Ironically, however, this has led to high rates of survival of very premature infants who would have had little chance of survival in the past.

Since these very premature infants are at the highest risk of developing ROP, the condition may actually be becoming more common again.

There are 5 stages of ROP.

• Stage I: There is mildly abnormal blood vessel growth.
• Stage II: Blood vessel growth is moderately abnormal.
• Stage III: Blood vessel growth is severely abnormal.
• Stage IV: Blood vessel growth is severely abnormal and there is a partially detached retina.
• Stage V: There is a total retinal detachment.

The blood vessel changes cannot be seen with the naked eye. An eye exam is needed to reveal such problems.

An infant with ROP may be classified as having “plus disease” if the dilation and twisting of the blood vessels matches or exceeds a standard photograph.

Symptoms of severe ROP include:

• Abnormal eye movements
• Crossed eyes
• Severe nearsightedness
• White-looking pupils (leukocoria)

High-risk infants and those younger than 30 weeks gestation or born weighing fewer than 3 lbs should have retinal exams.

The first exam usually should be 4 - 9 weeks after birth, depending on the baby’s gestational age. Babies born at 27 weeks or later usually have their exam at 4 weeks of age. Those born earlier usually have exams later.

Follow-up examinations are determined based on the results of the first exam. Babies do not need another examination if the blood vessels in both retinas have completed normal development.

Parents should know what follow-up eye exams are needed before the baby leaves the nursery.

Early treatment has been shown to improve a baby’s chances for normal vision. Treatment should start within 72 hours of the eye exam.

Some babies with “plus disease” need immediate treatment.

Treatment may include cryotherapy (freezing) to prevent the spread of abnormal blood vessels.

Laser therapy (photocoagulation) may be used to prevent complications of advanced ROP. The laser therapy stops the abnormal blood vessels from growing. It can be performed in the nursery using portable equipment. To be effective, it must be done before scarring and detachment occurs

Surgery is needed if the retina detaches. Surgical procedures continue to improve, but may not result in good vision.

Most premature infants with ROP recover with no lasting visual problems. Many premature infants with slight problems in retinal blood vessel growth have the vessels return to normal without treatment. Most infants with mild ROP can be expected to recover completely.

About 1 out of 10 infants with early changes will develop more severe retinal disease. Severe ROP may lead to significant vision problems or blindness. The most important factor in the outcome is early detection and treatment.

Complications may include severe nearsightedness and blindness.

Most infants with severe vision loss related to ROP have other complications of prematurity and require a multidisciplinary approach to rehabilitation.

The most effective prevention of retinopathy of prematurity is prevention of premature birth. Preventing other complications of prematurity (such as neonatal respiratory distress syndrome) may also help prevent ROP.

Section on Ophthalmology American Academy of Pediatrics, American Academy of Ophthalmology, American Association for Pediatric Ophthalmology and Strabismus. Screening examination of premature infants for retinopathy of prematurity. Pediatrics. 2006 Feb;117(2):572-6.

Early Treatment For Retinopathy Of Prematurity Cooperative Group. Revised indications for the treatment of retinopathy of prematurity: results of the early treatment for retinopathy of prematurity randomized trial. Arch Ophthalmol. 2003 Dec;121(12):1684-94.

International Committee for the Classification of Retinopathy of Prematurity. The International Classification of Retinopathy of Prematurity revisited. Arch Ophthalmol. 2005 Jul;123(7):991-9.

Tasman W. Retinopathy of Prematurity: the life of a lifetime disease. Am J Ophthalmol. Jan 2006; 141(1): 167-74.

Yanoff M, Duker JS, Augsburger JJ, et al. Ophthalmology. 2nd ed. St. Louis, Mo: Mosby; 2004.