Retinopathy of Prematurity Stages: What Every Parent Needs to Know

Are you overwhelmed researching ROP? We know how stressful the diagnosis is for new parents. That's why we summarized everything you need to know about the different retinopathy of prematurity stages in one article.

Whether you're an expecting parent or caring for a preemie, you deserve clear and concise information to understand this condition. From the symptoms at each ROP stage to potential complications and treatment options, read on to learn more.

General Information about Retinopathy of Prematurity

Retinopathy of prematurity (ROP) is when abnormal blood vessels grow in the retina. Since the retina is a light-sensitive tissue layer at the back of the eye, such an abnormality inevitably causes eye problems.

The retinopathy of prematurity stages are five. The higher the number, the more severe the case, with Stage 1 being mild abnormal blood vessel growth; and Stage 5 being complete retinal detachment.

ROP is most common in preterm babies. The risk factors for retinopathy of prematurity are:

Premature birth (before 31 weeks)
Low birth weight (less than 1500 grams)
Prolonged oxygen therapy or respiratory distress
Infections during pregnancy or after birth

ROP itself isn’t entirely preventable. however, proper prenatal care can minimize premature birth risks.

Most babies with ROP don’t show noticeable symptoms early on, only in the severe stages. A doctor can diagnose ROP after a pediatric eye exam. In advanced retinopathy of prematurity stages, though, parents may notice the following behavior in their infant:

Abnormal eye movements
White pupils (leukocoria)
Trouble focusing on objects

If untreated, retinopathy of prematurity can have potential complications:

Severe vision loss or blindness
Strabismus (misaligned eyes)
Amblyopia (lazy eye)
Myopia (nearsightedness)
Retinal detachment (in Stages 3 to 5)

Retinopathy of Prematurity Zones

Doctors use three retinopathy of prematurity zones to describe the location of abnormal growth in the retina:

Zone I: The innermost circle, around the optic nerve. ROP here is more severe and harder to treat.
Zone II: A larger circle surrounding Zone I, extending to the eye's periphery.
Zone III: The outermost circle, where blood vessel growth issues are less common.

Understanding the zones can determine the severity and urgency of treatment.

Retinopathy of Prematurity Stages

ROP classification includes five retinopathy of prematurity stages. The stages are based on the severity of abnormal blood vessel growth:

Stage 1: Mild Abnormal Blood Vessel Growth

At this stage, blood vessels in the retina grow irregularly, but the changes are minor. Eye doctors can see a thin, flat demarcation line separating the vascularized retina from the avascular retina. Since the abnormal vessels are confined to the retina, they don't significantly disrupt its function.

No visible symptoms
Diagnosis only during an eye exam
Stage 1 ROP often resolves naturally, with no long-term effects on vision
No medical or surgical intervention is required

Stage 2: Moderate Abnormal Blood Vessel Growth

The abnormality becomes more pronounced, forming ridges where the normal retina meets the area without developed blood vessels. These ridges are a hallmark of progression and may contain popcorn lesions a.k.a. small tufts of new blood vessels. This retinopathy of prematurity stage requires close monitoring.

No visible symptoms
Diagnosis only during an eye exam
Stage 2 ROP often resolves on its own without intervention
A small percentage of Stage 2 ROP may progress to more severe stages
No medical or surgical intervention is required unless the condition advances

Stage 3: Severe Abnormal Blood Vessel Growth

In Stage 3, the blood vessels grow abnormally into the vitreous (the jelly-like substance inside the eye) rather than staying within the retina. This abnormal growth is termed "extraretinal fibrovascular proliferation." The retina begins to swell, and there is a risk of detachment.

No visible symptoms
Significant risk for complications if left untreated
Some cases of Stage 3 ROP regress naturally
Immediate treatment for severe growth and plus disease* to prevent retinal detachment
Treatment is laser therapy or Bevacizumab injections

*Plus disease is a critical factor in Stage 3. The term refers to signs of severe disease, such as increased tortuosity (twisting) and dilation of retinal blood vessels, clouding of the vitreous, and poor dilation of the pupils during exams.

Stage 4: Partial Retinal Detachment

In the 4th retinopathy of prematurity stage, the retina starts to pull away (detach) from the back of the eye. Detachment in Stage 4 is partial, meaning only a section of the retina is affected.

Stage 4A is when the retinal detachment spares the macula.

Stage 4B is when the detachment of the retina involves the macula.

No visible symptoms, except trouble focusing on objects
Risk of vision impairment or loss becomes a significant concern
Without treatment, the condition may progress to complete detachment (Stage 5)
Treatment is surgical: vitrectomy or scleral buckling

Stage 5: Complete Retinal Detachment

Stage 5 is the most severe of the retinopathy of prematurity stages. The retina is fully detached, leading to significant structural damage to the eye and, without intervention, permanent blindness. The retina may appear funnel-shaped under examination.

Severe vision loss or blindness is evident
A white pupil (leukocoria) may be visible
The prognosis is poor without immediate surgical intervention
Even with treatment, restoring vision fully at Stage 5 is unlikely
Treatment is surgical: vitrectomy

The advanced surgical procedures aim to salvage any remaining vision.

Treatment for Different Retinopathy of Prematurity Stages

Observation (Stages 1 & 2)

Mild cases of ROP tend to resolve as the baby’s eyes mature. Regular monitoring by a pediatric ophthalmologist ensures the condition does not progress to severe retinopathy of prematurity stages. Eye exams are typically scheduled every 1-2 weeks until the retina is fully vascularized.

Laser Therapy (Stage 3)

Laser therapy prevents abnormal blood vessel growth by halting it in the peripheral retina. This is a standard treatment for Stage 3 ROP with "plus disease." Laser therapy uses a focused beam to target the peripheral retina where abnormal blood vessel growth occurs and reduces the risk of retinal detachment. While effective, it can cause partial peripheral vision loss as a trade-off for preserving central vision.

Avastin for Retinopathy of Prematurity (Stage 3)

Avastin (Bevacizumab) is an injection into the eye that blocks abnormal blood vessel growth. This anti-VEGF (vascular endothelial growth factor) medication is useful for cases where laser therapy may not be practical, such as when the disease affects Zone I.

Vitrectomy Surgery (Stages 4 & 5)

Vitrectomy is a surgical procedure to reattach the retina in severe cases of retinal detachment. The delicate surgery removes the vitreous gel and any fibrous tissue pulling on the retina. The surgeon may reposition or flatten the retina to restore its attachment to the back of the eye. In some cases, lens-sparing vitrectomy (LSV) is used to preserve the natural lens, optimizing vision development in infants.

Combination Therapies (Stages 3 to 5)

In severe cases, a combination of treatments like injections followed by laser therapy or vitrectomy may be required. For example, Avastin might be used first to reduce vascular activity, followed by laser therapy to stabilize the retina.

Respiratory Support for Newborns

Managing oxygen levels in premature babies is critical, as prolonged high oxygen exposure is a significant risk factor for ROP. Neonatal care teams carefully monitor and adjust oxygen therapy to minimize risk while ensuring adequate respiratory support.

In summary...

ROP stages range from mild (Stage 1) with a simple demarcation line to severe (Stage 5) with total retinal detachment. Early stages often resolve naturally, but advanced stages require intervention to prevent blindness. Screening every single premature baby, recognizing and treating ROP early is necessary for preserving vision in preterm infants.

Resources:

Retinopathy of Prematurity, DynaMed
Retinopathy of Prematurity, Cleveland Clinic

✅ Medically reviewed

Checked by Atanas Bogoev, MD.