Retinopathy of Prematurity

Retinopathy of prematurity is an eye disease that affects babies born too early. While most cases resolve on their own, some require treatment to prevent vision loss or blindness. Early screening and timely care can protect a baby’s sight.

Table of contents

• What is retinopathy of prematurity?
• Which babies are at risk?
• What causes this condition?
• Stages of the disease
• Signs and symptoms
• How is it diagnosed?
• Treatment options
• Outlook and long-term effects
• Associated anatomy

What is retinopathy of prematurity?

Retinopathy of prematurity (ROP) is an eye disease that can happen in babies who are born prematurely or who weigh less than about 3 pounds at birth^[1]. The condition involves abnormal growth of blood vessels in the retina, which is the light-sensitive layer of tissue at the back of the eye that converts light into visual messages sent to the brain^[5].

The blood vessels in a baby’s retina are not completely developed until close to the time of birth. When babies are born early, these blood vessels may not have finished developing normally. In premature babies, the blood vessels can stop growing for a time, and then when they start growing again, they may develop abnormally^[5]. These new abnormal vessels are fragile and can leak or bleed, which may result in swelling of the retina or scarring^[3].

Most babies with ROP have mild cases that get better on their own without treatment. About 90% of babies with ROP do not need medical treatment and go on to have normal vision^[2]. However, in more severe cases, the abnormal blood vessels and scar tissue can pull on the retina, causing it to detach from the wall of the eye. This is called retinal detachment, and it can lead to serious vision problems or even blindness if not treated^[1].

Which babies are at risk?

Babies are most at risk for ROP if they are born before 30 to 31 weeks of pregnancy or weigh less than about 3 to 3.3 pounds at birth^[1][2]. The earlier a baby is born and the lower their birth weight, the higher their risk of developing ROP^[2].

In the United States, about 14,000 to 16,000 infants develop some degree of ROP each year^[2]. Roughly half of the estimated 28,000 premature babies born each year have some level of retinopathy of prematurity^[5].

Besides being born early and having low birth weight, babies are also more likely to develop ROP if they have breathing problems and receive oxygen therapy to treat those problems. Other risk factors include infections, heart defects, anemia, bleeding in the brain, and other medical problems that premature babies commonly face^[1][4].

What causes this condition?

Normally, blood vessels in the retina start to develop around the fourth month of pregnancy and are not completely formed until close to the time of birth^[1]. When a baby is born prematurely, this development is interrupted.

After birth, the blood vessels that were still forming may stop growing for a period of time. During this pause, the retina starts producing growth factors to encourage vessel development. Sometimes too many growth factors are produced, which causes the vessels to grow abnormally and in random directions rather than staying in the proper layer of the retina^[5].

These abnormal blood vessels are fragile and prone to leaking or bleeding. The resulting fluid buildup and bleeding can damage the retina. If too much abnormal tissue develops, it can create scar tissue that pulls on the retina, potentially causing it to detach from the back of the eye^[5].

While doctors understand that premature birth disrupts normal blood vessel development, they do not yet fully understand every factor that causes ROP^[5]. Both too much oxygen and too little oxygen can contribute to the development of the condition^[4].

Stages of the disease

Doctors classify ROP into five different stages to track how serious the condition is. The stages range from stage 1, which is mild, to stage 5, which is severe^[1].

Stages 1 and 2 are mild forms of ROP. Babies at these stages usually get better without treatment and go on to have healthy vision. Doctors carefully monitor babies at these stages to see if the condition worsens^[1]. In stage 1, a line appears on the retina separating normal retina from premature retina. In stage 2, a ridge with height and thickness forms on the retina^[6].

Stage 3 is when fragile new abnormal blood vessels begin growing on the retina^[6]. Some babies who develop stage 3 get better with no treatment and go on to have healthy vision. However, others need treatment to stop the abnormal blood vessels from damaging the retina and causing retinal detachment^[1]. This is usually when doctors recommend starting treatment.

Stage 4 means the retina has partially detached and requires treatment^[1].

Stage 5 is the most severe. At this stage, the retina has completely detached. Even with treatment, babies in stage 5 may experience vision loss or blindness^[1].

Doctors also describe ROP by the location in the eye where it occurs, called zones, and by whether the blood vessels appear thick and wavy, which is called “plus disease”^[6]. It’s important to note that babies in any stage can get worse quickly and need treatment, which is why regular follow-up exams are essential^[1].

Signs and symptoms

There are no visible signs of ROP that parents can see in their baby’s eyes during the early stages. Babies with ROP do not feel pain or look different^[2][6]. This is why screening by an eye specialist is so important for at-risk babies.

If ROP causes damage or progresses to advanced stages with retinal detachment, parents may later notice certain signs as their child grows. These can include eyes that wander, shake, or make other unusual movements, eyes that don’t follow objects, pupils that look white, or trouble recognizing faces^[1].

Babies who had ROP are also at higher risk for developing other eye problems as they get older. These include retinal detachment, nearsightedness (difficulty seeing things far away), amblyopia or lazy eye (when one eye doesn’t develop normal vision), and crossed eyes^[1]. Regular checkups and eye exams throughout childhood are important to find and treat these problems early and protect the child’s vision^[1].

How is it diagnosed?

ROP is diagnosed through an eye examination performed by an eye doctor called an ophthalmologist who is skilled in examining infant eyes^[6]. Only this specialized examination can detect the condition.

Before the exam, the baby’s pupils are dilated with eye drops to make them larger. This allows the doctor to see inside the eye and examine the retina at the back^[6]. During the examination, the doctor may use a tool called a speculum to hold the baby’s eye open. This is not painful, although babies often cry during the exam^[9].

All infants who weigh less than 1,500 grams (about 3.3 pounds) or who are born before 31 weeks of pregnancy should receive eye examinations to screen for ROP^[6]. Other babies considered high risk by their doctors may also be screened. If a baby is able to leave the hospital before getting screened, an appointment will be scheduled to check their eyes^[9].

The timing and frequency of screening exams depend on the baby’s gestational age at birth and their condition. It is critical that parents keep all scheduled follow-up appointments, as ROP can progress quickly and timely detection is essential for successful treatment^[1].

Treatment options

For babies with mild ROP in stages 1 and 2, treatment usually involves careful observation. Doctors will monitor the baby’s eyes regularly to see if the condition improves on its own or if it worsens and requires intervention^[1]. Only about 10% of babies with ROP need medical treatment^[9].

When ROP reaches a point where treatment is needed (typically in stage 3 or higher), several treatment options are available:

Eye injections are often the first choice for treatment. A medication is injected into the eye to slow or stop the growth of abnormal blood vessels. This procedure can be done at the baby’s hospital bed, is very effective, and is not painful^[9][5]. Because this treatment is safe and works well, most doctors prefer it. However, as this is a newer treatment, research continues to determine long-term effects^[3].

Laser treatment, also called laser therapy or photocoagulation, is commonly used for ROP. Small laser beams create scars on the peripheral retina (the sides of the retina). This stops the abnormal blood vessel growth and prevents the retina from pulling away^[3]. The treatment focuses on the side areas of the retina to preserve the central retina, which is the most important part for clear vision^[3]. While a baby’s eyes may be red and puffy for a couple of days after laser surgery, the baby will not have much pain^[9].

For more advanced cases of ROP where the retina has already started to detach, surgery may be necessary. Two surgical approaches include:

Scleral buckling involves placing a flexible band, usually made of silicone, around the white part of the eye. The band pushes in on the eye, which helps the detached retina move back into its proper position against the eye wall^[3].

Vitrectomy is a procedure where the doctor removes the gel-like substance inside the eye and cuts away scar tissue that is pulling on the retina. This allows the retina to lie flat against the back of the eye again^[3].

Even with treatment, babies with stages 4 and 5 may still experience some vision loss. This is why doctors usually start treatment at stage 3, before the retina detaches^[1].

Outlook and long-term effects

The outlook for babies with ROP depends largely on how severe the condition is and whether it is detected and treated early. Up to 90% of babies with ROP have mild cases that resolve without treatment and go on to have normal vision^[2].

For babies who require treatment, the success depends on the stage at which treatment begins and how well the baby responds. Early detection through screening and prompt treatment when needed give babies the best chance for good vision^[5].

In the United States, ROP causes legal blindness in about 400 to 600 infants each year^[2][6]. However, with proper screening and treatment, many cases of vision loss can be prevented.

Even if a baby’s ROP resolves without causing retinal detachment, children who had the condition are more likely to develop vision problems later in life. These can include nearsightedness, lazy eye, crossed eyes, and an increased risk of retinal detachment as they grow older^[1].

Because of these risks, it is essential that children who had ROP continue to receive regular eye examinations throughout childhood. Finding and treating any eye problems early will help protect the child’s vision as they develop^[1].

Associated anatomy

• Retina
• Eye