Retinopathy of Prematurity (ROP)

Description

Retinopathy of Prematurity (ROP), also known as retrolental fibroplasia, is a potentially blinding condition affecting the retina of newborns. In the 1950s it was associated with the use of high amounts of oxygen in neonatal units. Today, modern neonatal care has curbed the incidence, yet because the survival rate of low birth weight infants is much higher, the exposure of surviving babies to required oxygen levels is increasing. The factors that put infants at greatest risk of developing ROP are low birth weight (less than 3.5 pounds) and premature delivery (26-28 weeks). In babies born prematurely, the growth and development of normal blood vessels in the retina is halted and abnormal vessels may begin to develop. The problem with abnormal vessel growth, known as neovascularization, is that it does not deliver adequate oxygen supply to the retina. In addition, it may cause many secondary problems. ROP is classified in five stages, depending on the extent of the disease. Progression of the disease to later stages can lead to the formation of scar tissue in the retina and complications such as: retinal detachment, vitreous hemorrhage, strabismus, and amblyopia. Many children with ROP develop nearsightedness.

Symptoms

Because newborns cannot communicate their symptoms, parents, neonatologists, pediatricians and ophthalmologists are keenly aware of risk factors for ROP:
  • Low birth weight (3.5 pounds or less)
  • The need for any oxygen within the first week after birth
  • Unstable health immediately after birth
Children with ROP as infants should be watched for the following symptoms that could signal underlying problems that may not surface until later:
  • Holding objects very close
  • Difficulty seeing distant objects
  • Favouring or winking one eye
  • Reluctance to use one eye
  • Poor vision (previously undetected by the physician)
  • Sudden decrease of vision
  • Crossed or turned eye

Causes

Retinopathy of prematurity (ROP) is caused by the abnormal growth of new blood vessels (neovascularisation) throughout the retina. Often these new blood vessels are weak and can leak causing scar tissue to form on the retina. This scar tissue can cause retinal tears and eventual retinal detachment by pulling it out of position. Retinal detachment is the main cause of visual impairment associated with ROP. There are several factors that may be responsible for the development of ROP. The eye starts to develop with the blood vessels of the retina at the optic nerve (nerve responsible for relaying light signals to the brain to produce images) at the back of the eye from 16 weeks of pregnancy. The blood vessels grow gradually to the edges of the developing retina supplying the tissue with oxygen and nutrients. The last 12 weeks of pregnancy the eye develops rapidly and the retinal blood vessel growth is almost complete at birth. If a baby is born prematurely, before these blood vessels have reached the edge of the retina, normal vessel growth may stop. This will result in areas of the retina being starved of oxygen and nutrients. Scientists believe there are signals sent out by the body to restart the growth of blood vessels but it is these new vessels that are weaker and may begin to leak and cause scars on the retina. When the scars shrink this pulls on the retina creating tears or holes where eye fluid can enter and build up causing retinal detachment.

Diagnosis

All premature babies that fall within a lower weight category are routinely asses for ROP. These infants at risk should be examines by 4 to 6 weeks of age. An eye doctor will dilate the pupils of the child using eye drops which will allow for a better view inside the eye used an ophthalmoscope (magnifying glass-like device with a bright light). Depending on the amount of new blood vessel growth the ROP is graded and reassessment will occur every 1 to 2 weeks depending on a number of factors. These factors may include; the severity and location of ROP, the rate of progression of new blood vessel formation. The stages of ROP are outlined below. Stage 1 ROP Mild growth of new bloody vessels. Most children who develop Stage 1 improve on their own and do not need treatment. Regular  checks must still be observed. Stage 2 ROP Moderate abnormal growth of blood vessels. Most children who develop Stage 3 improve on their own and do not need treatment. Regular  checks must still be observed. Stage 3 ROP Severe abnormal growth of blood vessels. The new blood vessels grow towards the centre of the eye instead of towards the periphery (side) of the retina. Some children who develop Stage 3 improve on their own and do not need treatment. Regular checks must still be observed. However, some infants  might develop Stage 3 plus disease which means the new blood vessels have begun to enlarge and twist, indicating disease progression. At this point treatment is advised. Stage 4 ROP Partially detached retina. Pull from retinal scars is apparent and leaking blood vessels. Treatment is required Stage 5 ROP Retinal detachment. This is the end stage of the disease. If left untreated infants can be left with serious visual impairments or even total blindness. The majority of infants that develop ROP are graded between Stage 1 and Stage 2.

Treatment

The most common intervention for the treatment of late stage Retinopathy of prematurity (ROP) is laser surgery. The purpose of laser surgery is to stop the abnormal growth of new blood vessels. Laser photocoagulation is performed to remove the parts of the retina that had not developed fully including formed blood vessels. It is possible that this intervention does not stop disease progress and in these cases partial or full retinal detachment may develop. This will then require a separate surgery. The severity of the detachment will be the determining factor in the degree of visual impairment of the infant. No matter what level of vision a person may have, it is important to look after the eyes. To find out more about what can be done to take care of the eyes on a daily basis, please visit our Tips for Good Eye Health. For further information, please contact the Research Department on 01 6789004 or email research@fightingblindness.ie.

Research

Researchers and clinicians are continually seeking to improve interventions and outcomes of treatment of retinopathy of prematurity (ROP). Current clinical trials are investigating methods of identifying high risk infants earlier with an aim of preventing significance disease progression. The Early Treatment for Retinopathy of Prematuriy study (ETROP) is designed to determine whether earlier treatment improves the visual outcome of affected infants. Information about other clinical trials that are on-going and completed can be found on the clinical trials website and can be searched by both condition and location.

Support

Receiving a diagnosis can be overwhelming for anyone, but this is not a journey that you have to make alone. There are many groups and resources available to provide support for people living with Stargardt Disease. Fighting Blindness offers a free and confidential counselling service (Insight Counselling). For further information please contact insight@fightingblindness.ie or call 01 6746496. We also offer support groups for people with a visual impairment to share their feelings and experiences with others facing the same challenges. Please consult the support groups section of our website here to access the latest timings and days for the various support groups we offer. For further information please contact insightgroups@fightingblindness.ie or call 01 6746496.

Resources

Féach provides support for parents of children living with sight loss in Ireland. ChildVision is the national education centre for children with sight loss in Ireland. NCBI (National Council for the Blind in Ireland) provides support and services for people living with sight loss in Ireland. Irish Guide Dogs for the blind helps individuals and their families to achieve improved mobility and independence.