Diagnosis and Treatment of Retinopathy of Prematurity (ROP)

A baby born before 37 weeks of gestation is considered premature. Approximately 300 out of every one million live births result in blindness due to retinopathy of prematurity (ROP) in at least one eye.

Which Premature Infants Should Undergo an Eye Examination?

The American Academy of Ophthalmology recommends ROP screening for infants with:

Birth weight below 1500 grams
Gestational age of 32 weeks or less

Additionally, infants with a birth weight of 1500-2000 grams or a gestational age of 30 weeks or more who have an unstable clinical course should undergo at least two indirect ophthalmoscopic retina examinations. If the retinal vascularization is fully developed, a single examination is sufficient.

When Is Retinal Vascularization Completed?

Retinal vascularization begins at the optic nerve at 16 weeks of gestation.
The nasal (inner) retina becomes fully vascularized at 36 weeks.
The temporal (outer) retina completes vascularization by 40-42 weeks.

When Should the First ROP Screening Be Done?

The first ROP examination should be performed between 4 to 6 weeks after birth or at 31 to 33 weeks of gestational age.

When Can ROP Screenings Be Stopped?

Screenings should continue until retinal vascularization is complete or until 50-55 weeks post-birth, depending on the severity and stage of the disease.

How Common Is ROP?

66% of infants weighing less than 1251 grams at birth show ROP findings.
82% of infants weighing less than 1000 grams develop ROP.

Which Systemic Factors Negatively Affect ROP?

Sepsis
Intraventricular hemorrhage
Heart disease
Lung disease

Which Infants Require Treatment?

ROP is classified into three zones based on retinal involvement:

Zone 1 (innermost, near the optic nerve)
Zone 2 (middle region)
Zone 3 (outermost)

The disease progresses through five stages, with plus disease being a critical factor indicating disease severity. Plus disease refers to venous dilation and arterial tortuosity in the retina and plays a significant role in treatment decisions.

Treatment is required if:

Stage 3 ROP involves at least five contiguous or eight non-contiguous clock hours of retinal involvement with plus disease. This is termed threshold ROP.
In Zone 1, treatment is initiated even without plus disease if Stage 3 is present.
In Zone 1, treatment is also given if plus disease is present, even without Stage 3 ROP.

Treatment Options

Intravitreal Anti-VEGF Therapy (Bevacizumab – Avastin)
- First-line treatment for Zone 1 ROP
- Inhibits abnormal blood vessel growth
Laser Photocoagulation
- First-line treatment for threshold ROP in Zone 2 and 3
- If laser treatment is insufficient, intravitreal anti-VEGF injections are used.
Surgical Treatment (for advanced stages)
- Stage 4 & 5 ROP cases require surgery.
- Vitrectomy or scleral buckling may be performed for retinal detachment.

Natural Course and Possible Outcomes

7% of infants weighing less than 1251 grams eventually develop threshold ROP.
85% of Stage 1 & 2 ROP cases resolve spontaneously.

Complications of Resolved ROP

Myopia (nearsightedness)
Astigmatism
Amblyopia (lazy eye)
Strabismus (eye misalignment)
Vitromacular scarring
Glaucoma
Cataracts
Tractional retinal detachment
Macular pigment changes

Treatment Outcomes and Long-Term Management

Oxygen Saturation: Keeping oxygen levels between 96-99% may prevent progression of pre-threshold ROPbut does not significantly reduce the need for laser therapy.
Light Exposure: The LIGHT-ROP study found no significant impact of ambient light exposure on ROP development or severity.
Cryotherapy: Previously used for threshold ROP, cryotherapy halved the risk of complications like macular traction, retinal detachment, and lens scarring. However, laser therapy has now replaced cryotherapy due to its better visual outcomes and less traumatic effects.

Surgical Treatment for Advanced ROP

Stage 4 ROP: Treated with scleral buckling or vitrectomy.
Stage 5 ROP: Vitrectomy with removal of retinal traction bands.
- Retinal reattachment is successful in 30% of cases.
- After 5 years, 25% of eyes remain stable.

Early detection and timely intervention can significantly reduce blindness caused by ROP, highlighting the importance of regular screening and follow-up for premature infants.