Retinopathy of Prematurity (ROP) is an eye condition affecting premature infants, particularly those born very early or with a low birth weight. It involves the abnormal growth of blood vessels in the retina, the light-sensitive tissue at the back of the eye. Avastin (bevacizumab) is a medication used to treat this condition.
Understanding Retinopathy of Prematurity (ROP)
ROP is an eye disease characterized by the abnormal development of blood vessels in the retina. The retina is the layer of tissue at the back of the eye that converts light into electrical signals, which the brain then processes to create images.
In a full-term pregnancy, retinal blood vessel growth typically completes a few weeks before birth. However, if a baby is born prematurely, this normal development is interrupted, leading to the potential for abnormal vessel growth after birth. These abnormal blood vessels are fragile and can leak or bleed, leading to scarring and, in severe cases, retinal detachment, which can cause vision loss or blindness.
ROP is categorized into five stages, ranging from mild (Stage 1) to severe (Stage 5). While Stages 1 and 2 often resolve without intervention, Stage 3 may require treatment to prevent retinal damage, and Stages 4 and 5 involve partial or complete retinal detachment, often necessitating urgent treatment. There are typically no visible signs of ROP that parents can observe; a pediatric ophthalmologist uses specialized instruments to detect the condition.
How Avastin Addresses ROP
Avastin, also known by its generic name bevacizumab, functions as an anti-VEGF (Vascular Endothelial Growth Factor) medication. VEGF is a naturally occurring protein that plays a role in the formation of new blood vessels, a process called angiogenesis. In the context of ROP, an imbalance in VEGF levels can lead to the excessive and disorganized growth of blood vessels in the retina.
Avastin works by binding to and neutralizing VEGF, thereby blocking its ability to promote abnormal blood vessel proliferation. By inhibiting this growth factor, Avastin helps to stop the progression of the problematic retinal vessels in premature infants. This action can lead to the regression of these abnormal vessels, allowing for more normal retinal development. It is a treatment option for severe ROP, and has shown benefits over traditional laser therapy in some situations.
The Avastin Treatment Procedure
Avastin treatment for ROP involves an injection directly into the baby’s eye. This procedure is performed in a specialized setting, such as a Neonatal Intensive Care Unit (NICU) or an operating room, to ensure a sterile environment and close monitoring.
Before the injection, the baby’s eye is numbed with local anesthetic eye drops to minimize discomfort. The ophthalmologist administers a very small dose of bevacizumab, between 0.002 mg and 0.016 mg, directly into the vitreous gel of the eye.
The injection process is quick, taking less time than other treatments like laser therapy, which can require longer sedation. Following the injection, the baby may receive antibiotic eye drops for a few days to prevent infection. The medical team will provide instructions for immediate post-treatment care.
Expected Outcomes and Follow-Up
Avastin treatment for ROP aims to halt the abnormal growth of retinal blood vessels, leading to their regression and helping to preserve the infant’s vision. Studies have shown that a significant percentage of eyes, around 82.9% to 92.9%, demonstrate favorable structural outcomes after one or two injections. This can allow for continued, more normal development of the retinal vasculature.
Temporary side effects may occur, such as redness or swelling of the treated eye. Avastin can be absorbed into the baby’s bloodstream. While no significant short-term systemic side effects have been consistently reported, long-term systemic effects are still being studied.
Regular, long-term ophthalmologic follow-up appointments are necessary after Avastin treatment. These appointments, initially weekly and then bi-weekly until a postmenstrual age of around 90 weeks, monitor for any recurrence of ROP or other vision issues and ensure proper retinal development.