Retinopathy of Prematurity (ROP) – Causes & Treatment

What is Retinopathy of Prematurity?

Retinopathy of Prematurity (ROP) is a potentially sight-threatening eye disease that affects premature infants. In a full-term pregnancy, the blood vessels that supply the retina (the light-sensitive layer at the back of the eye) finish developing just before birth. When a baby is born prematurely, this development is incomplete. After birth, abnormal and excessive blood vessel growth can occur in the retina, which may lead to scarring and, in severe cases, retinal detachment and blindness.

ROP is one of the leading causes of childhood blindness in high-income countries. However, with proper screening and timely treatment, most cases can be managed effectively and permanent vision loss can be prevented.

Causes and Risk Factors

The primary cause of ROP is the immaturity of the developing retinal vasculature at the time of premature birth. The sudden change in the oxygen environment outside the womb can disrupt the normal process of blood vessel growth in the retina.

• Gestational age: The earlier a baby is born (especially before 32 weeks of gestation), the higher the risk of developing ROP.
• Low birth weight: Infants weighing less than 1,500 grams at birth are at particularly high risk.
• Oxygen therapy: While often life-saving, supplemental oxygen can influence abnormal vessel growth in the retina.
• Other factors: Infections, anemia, blood transfusions, and other complications of prematurity can increase the risk.

Symptoms and Progression

In its early stages, ROP causes no visible external symptoms. Parents and caregivers cannot detect the condition without a medical examination. This is why systematic eye screening programs are essential for all at-risk premature infants.

In more advanced stages, the following signs may become apparent:

• A white or cloudy appearance in the pupil (leukocoria)
• Crossed or misaligned eyes (strabismus)
• Reduced visual responsiveness in the infant
• In the most severe cases: retinal detachment and loss of vision

ROP is classified into five stages of severity. Stages 1 and 2 often resolve on their own without treatment, while stages 3, 4, and 5 typically require active medical intervention.

Diagnosis

Because ROP has no early external symptoms, regular ophthalmological screening is mandatory for all premature infants at risk. Standard screening guidelines include:

• Infants born before 32 weeks of gestation or weighing less than 1,500 grams at birth should be screened.
• The first examination is typically performed at around 6 to 7 weeks of age or from the 31st to 32nd postmenstrual week.
• Screening is performed by a specialist ophthalmologist using indirect ophthalmoscopy after dilation of the pupil with eye drops.

Treatment

Treatment depends on the stage and severity of ROP. Mild cases (stages 1 and 2) are often monitored closely and may regress spontaneously, while more advanced cases require active treatment.

Laser Photocoagulation

Laser photocoagulation is the established standard treatment for advanced ROP. A laser is used to ablate the poorly vascularized peripheral areas of the retina, stopping abnormal vessel growth and reducing the risk of retinal detachment.

Intravitreal Anti-VEGF Therapy

A newer treatment option involves injecting anti-VEGF agents (such as bevacizumab or ranibizumab) directly into the vitreous cavity of the eye. These drugs inhibit vascular endothelial growth factor (VEGF), which drives the abnormal blood vessel proliferation characteristic of ROP. This approach is increasingly used, especially for aggressive or posterior forms of the disease.

Surgical Intervention

In stages 4 and 5, when partial or complete retinal detachment has occurred, surgical procedures such as vitrectomy (removal of the vitreous gel) or scleral buckling may be necessary. However, visual outcomes in these advanced stages are significantly more limited.

Follow-up and Long-term Outlook

Even after successful ROP treatment, ongoing ophthalmological follow-up is essential. Children treated for ROP have an increased risk of developing myopia (nearsightedness), strabismus (squinting), amblyopia (lazy eye), and glaucoma (increased eye pressure). Early prescription of corrective lenses and, if necessary, patching therapy can help support long-term visual development.

References

1. Hellstrom A, Smith LEH, Dammann O: Retinopathy of prematurity. The Lancet, 2013; 382(9902): 1445-1457.
2. World Health Organization (WHO): Blindness and vision impairment. Available at: https://www.who.int/news-room/fact-sheets/detail/blindness-and-visual-impairment
3. American Academy of Ophthalmology (AAO): Screening examination of premature infants for retinopathy of prematurity. Ophthalmology, 2018; 125(10): 1511-1515.