Retinopathy of prematurity (ROP)

Retinopathy of prematurity (ROP) is a potentially blinding disease caused by abnormal development of retinal blood vessels in premature infants. Infants weighing about 2¾ pounds (1250 grams) or less and are born before 31 weeks of gestation are more likely to be affected by ROP. Retina of the eye is the innermost layer, that receives light and turns it into visual information that is sent to the brain.

In Premature babies, the blood vessels that feed the retina haven’t finished growing, and get disturbed growth pattern due to premature birth. When ROP is severe, it can cause retinal detachment and possible blindness. Smaller a baby at birth, more likely chances are that baby will develop ROP. This disorder affects mostly both eyes and is the most common cause of vision loss in childhood and can lead to lifelong vision impairment and blindness.

How common is ROP?

With recent advances in neonatal care, premature babies are saved and not all premature infants develop ROP. Out of 20 million children born annually in India and 0.6 million admitted to NICUs all over the country, about 10% of these infants are at risk of developing ROP. As per the figure given by Clare Gilbert in 2010, there are about 0.3 million blind children (>15 years of age) in India and 10% of them are blind due to ROP. There are approximately 3.9 million infants born in the U.S. each year. About 14,000 are affected by ROP and 400-600 infants each year in the U.S. become legally blind from ROP. About 90 percent of all infants with ROP are in the milder category and do not need treatment.

How ROP Develops?

Eye formation starts at 16th week of pregnancy. Blood vessels begin forming around optic nerve. These blood vessels grow towards the edges of the developing retina supplying oxygen and nutrients. In the last 12 weeks, eye matures rapidly and if a baby takes birth prematurely, normal vessel growth may stop and retinal edges may be devoid of nutrients and oxygen. According to some studies, periphery of the retina sends out signals for nourishment and as a result, new abnormal vessels begin to grow. These newly formed vessels are weak and tend to bleed, leading to scarring of retina and ultimately detachment. This is the prime cause for blindness in ROP.

Risk Factors for ROP

Factors contributing to the risk of ROP include anemia, blood transfusions, respiratory distress, breathing difficulties, Hyperoxia, Hypoxia, Hypotension and the overall health of the infant. The most important risk factors for ROP are prematurity and low birth weight. Phototherapy is also attributed to the development of ROP.

Signs of Retinopathy of prematurity:

ROP shows variety of presentations:

• Avascular retina
• Scarring or dragging of the retina
• Vitreous hemorrhage
• Cataract Development
• Retinal detachment.

Do everyone need to see retina specialist

Premature babies before 30 weeks of gestation and babies who are underweight are at higher risk. These infants are always advised to visit eye doctor for checkup. Best time to visit retina specialist is preferred within 30 days of birth. Retinal screening done in this period is quite beneficial for the treatment of the infant.

Treatment

• Mild cases do not need any treatment, while in advanced cases a variety of treatment options are available. The most effective and proven treatment for ROP is laser therapy or cryotherapy.
• Late stages may require scleral buckle or Vitrectomy

Scleral buckle – It is usually done in stage IV or V. A silicone band is placed around the eye, It keeps the vitreous gel from pulling on the scar tissue and allows the retina to flatten back down onto the wall of the eye. This band is removed later as eye continues to grow; otherwise infant will develop myopia.

Vitrectomy – This is performed in stage V only and involves removing the vitreous and replacing it with a saline solution. Once vitreous has been removed, the scar tissue on the retina can be peeled back, allowing the retina to relax and lay back down against the eye wall.