Retinopathy of prematurity (Terry syndrome)
Retinopathy of prematurity (ROP), also known as Terry syndrome, is an eye disorder that primarily affects premature infants born before the thirty-first week of pregnancy and weighing less than 2.75 pounds. This condition is a leading cause of vision loss in infants, with the risk increasing as the infant's birth weight decreases. ROP typically affects both eyes and can lead to permanent vision impairment or blindness. Each year, approximately 14,000 to 16,000 infants are diagnosed with ROP, although 90% experience only mild symptoms. The disorder is classified into five stages, ranging from minor abnormal blood vessel growth to complete retinal detachment, which can result in severe visual impairment.
The development of ROP is linked to the premature growth of blood vessels in the retina, which can stop due to insufficient oxygen and nutrients. Abnormal vessels may form and lead to complications such as retinal detachment. Treatments for severe cases include laser therapy and cryotherapy to prevent further damage. In the most critical instances, surgical interventions like scleral buckling or vitrectomy may be necessary. While treatments can be effective, they do not guarantee recovery, highlighting the importance of ongoing monitoring and care for affected infants.
On this Page
Retinopathy of prematurity (Terry syndrome)
Retinopathy of prematurity (ROP), also called Terry syndrome, is an eye disorder characterized by retinal impairment. It mainly affects premature infants who are born before the thirty-first week of pregnancy and weigh less than 2.75 pounds. ROP is one of the most common causes of vision loss in infants. The smaller the child is at birth, the more likely he or she will develop the disorder. ROP usually affects both eyes of an infant and can lead to permanent vision impairment or blindness. ROP affects between fourteen thousand and sixteen thousand infants each year, 90 percent of whom only experience a mild form of the disorder. ROP is classified into five stages depending on the severity of symptoms. Between four hundred and six hundred infants develop ROP that is severe enough to cause blindness each year. Infants diagnosed with any stage of ROP have a higher risk of developing vision problems with age, such as glaucoma, myopia (nearsightedness), strabismus (crossed eyes), and amblyopia (lazy eye).
Background
ROP first came to the attention of medical professionals in the early 1940s, when physician Theodore Terry discovered a connection between eye development issues and prematurity. He called the disease retrolental fibroplasia (RLF). RLF was later identified as the fifth and most severe stage of ROP. The disorder was becoming very common among premature infants throughout the 1940s. Upon extended examination, doctors concluded that the condition was developing after birth, not during pregnancy. Experts initially believed this had something to do with the nursery equipment in hospitals, but by the end of the decade, research indicated excessive oxygen was to blame. Controlled trials showed that delivering a measured amount of oxygen to preterm infants in incubators led to fewer cases of RLF of all severities, and many infants in the trial did not develop RLF at all. Researchers concluded excessive oxygen caused RLF, but over the next few decades, the reemergence of the disease led to renewed interest in understanding its cause.
RLF practically disappeared in the 1950s and 1960s, but the disorder saw resurgence in the 1970s following the introduction of a number of neonatal technologies that improved the survival rate of premature newborns. With more preterm children surviving, the occurrence of RLF inflated; this led experts to believe that oxygen must not be the only culprit. Further studies were undertaken in search of a cause. By studying animal models, researchers discovered the disorder was related to the prematurity of the eye at birth. If the eye had not developed enough by the time the infant was born, RLF emerged. Scientists concluded eye prematurity to be the primary cause of RLF, which was renamed retinopathy of prematurity (ROP) to better reflect the disease's pathology.
Further studies helped medical professionals understand the prevalence of ROP, showing the earlier the birth the higher the risk of the disorder. Doctors also continued to associate improper oxygen administration with an increased risk of ROP despite being unsure if oxygen amounts actually contributed to the disorder. ROP was eventually classified into stages in 1983 following a number of conferences held by the National Eye Institute.
Overview
An unborn infant's eyes begin to develop at sixteen weeks of pregnancy. At this time, the blood vessels inside the retina begin forming at the back of the eye where the optic nerve is located. The blood vessels then begin slowly growing out toward the edge of the developing retina, the light-sensitive area of the eye responsible for receiving images and sending them to the brain. The blood vessels supply oxygen and nutrients to the retina. Rapid eye development occurs in the last twelve weeks of pregnancy, allowing blood vessels to develop into fully functional mechanisms. At full term, a baby's eyes have almost completely developed, allowing the retinas to grow over the first few weeks after birth. Preterm births occurring before the blood vessels have reached the retina can cause normal vessel growth to stop, depriving the retina of necessary oxygen and nutrients. The retina, in need of these vital materials, sends signals out to attract nourishment, leading to the growth of abnormal blood vessels. These vessels are very fragile and bleed easily, scarring the retina. These scars can shrink and pull on the retina, which can detach from the back of the eye. Total retinal detachment causes blindness. Other risk factors that could lead to ROP include anemia, blood transfusions, breathing difficulties, and poor birth health.
ROP is broken down into five stages. The first stage includes minor abnormal blood vessel growth. Infants born with stage one often recover with no treatment and grow to have normal vision. Stage two ROP involves greater abnormal blood vessel growth, but also normally resolves without treatment. At stage three, an infant's eyes have developed severe abnormal blood vessel growth, with the vessels expanding toward the center of the eyes rather than the surface of the retinas. While some infants do recover without treatment for ROP and gain normal sight, some patients with stage three develop twisted and enlarged blood vessels and require treatment to prevent retinal detachment. Infants with stage four ROP may suffer retinal scarring severe enough to partially detach the retina from the eye and require treatment. Stage five is the most severe degree of ROP, with the retina completely detaching from the eye. If left untreated, the child will experience extreme visual impairment or even blindness. Most premature infants will develop the first two stages of ROP, although more severe ROP does occur in a small percentage of newborns.
Two specific treatments are most effective in helping patients with severe ROP recover. Laser therapy burns away the outer edges of the retina; this either slows or reverses the growth of the abnormal blood vessels. Cryotherapy utilizes freezing temperatures to stop abnormal vessel growth. If an infant's retinal damage is beyond laser therapy and cryotherapy, the patient can undergo one of two treatment options. Sclera buckles, which are silicone bands, can be placed and tightened around the eye. This prevents scars from pulling the retina away from the eye, allowing the retina to flatten onto the eye wall. A procedure known as a vitrectomy is a treatment reserved for stage five patients. A vitrectomy removes the clear fluid that fills the space between the lens and retina, called the vitreous humour, and replaces it with saline (salt) solution. This allows doctors to cut away scar tissue on the retina, giving the retina freedom to relax against the eye wall. ROP treatments are commonly successful, but recovery is not guaranteed. If retinal detachment still occurs following treatment, surgery may be required.
Bibliography
Coats, David K. "Retinopathy of Prematurity: Involution, Factors Predisposing To Retinal Detachment, and Expected Utility of Preemptive Surgical Reintervention." Transactions of the American Ophthalmological Society, no. 103, Dec. 2005, pp. 281–312.
"Facts about Retinopathy of Prematurity (ROP)." National Eye Institute, www.nei.nih.gov/health/rop/rop. Accessed 4 Nov. 2016.
Friddle, Kim. "Pathogenesis of Retinopathy of Prematurity." MedScape, www.medscape.com/viewarticle/817909. Accessed 4 Nov. 2016.
Hartnett, Mary Elizabeth, and John S. Penn. "Mechanisms and Management of Retinopathy of Prematurity." New England Journal of Medicine, vol. 367, no. 26, 2012, 2515–26.
Lyon, Don W., and Danielle F. Warren. "A Clinical Guide to Retinopathy of Prematurity." Review of Optometry, 20 Dec. 2006, www.reviewofoptometry.com/article/a-clinical-guide-to-retinopathy-of-prematurity. Accessed 4 Nov. 2016.
Phelps, Dale L. "Retinopathy of Prematurity: History, Classification, and Pathophysiology." NeoReviews, vol. 2, no. 7, July 2001, 153–166.
"Retinopathy of Prematurity." International Agency for the Prevention of Blindness, www.iapb.org/knowledge/what-is-avoidable-blindness/retinopathy-prematurity. Accessed 4 Nov. 2016.
"Retinopathy of Prematurity." National Eye Institute, nei.nih.gov/health/rop. Accessed 4 Nov. 2016.