Retinopathy of Prematurity (ROP)
What is prematurity?
When a baby is born before it is fully developed it is considered premature. Mild prematurity is usually not a problem, but in cases of severe prematurity, when the baby is delivered months too early (less than 31 weeks of gestation), or the baby is 1250 grams (about 2.75 pounds) or less, the eyes are at risk for blindness.
How does prematurity of birth result in ROP and vision loss?
During a fetus’s growth in the mother’s womb, its retinal blood vessels normally grow out from the optic nerve to the edge of the peripheral retina. However in retinopathy of prematurity, the blood vessels have not had enough time to grow to the edge of the peripheral retina, so large patches of retina are present without any blood vessels.
This lack of blood flow makes the retinal cells release chemicals for new blood vessel growth. The new blood vessel growth, known as fibrovascular proliferation or neovascularization, causes excessive scar tissue and bleeding that result in vision loss.
If the baby is fortunate their retinal blood vessels fill in the missing peripheral areas naturally, the baby is deemed resolved and no treatment is necessary.
How is Retinopathy of Prematurity Treated?
Treating retinopathy of prematurity requires limiting the growth of new blood vessels. In moderate cases, laser ablation or occasionally cryotherapy (freezing the retina without blood vessels) is utilized to treat the areas of retinopathy. In severe cases close to the macula and optic nerve, antivegf injections are administered to the vitreous cavity of the eye if laser proves insufficient. If those treatment methods fail to stop the growth of new blood vessels, or if the blood vessels have turned into scar tissue and detached the retina, a vitrectomy or scleral buckle is required to try to reattach the retina.