The retina – the complex tissue of the back of the eye, where, among others, the photosensitive nerve cells that react to light to produce the phenomenon of vision – fully matures in humans between 43 and 45 weeks of gestation ; that is to say: in general, after birth.
This disorder usually affects babies born before the 31st week of gestation, weighing 2.75 pounds (approximately 1250 grams) or less at birth. In most cases, retinopathy of prematurity resolves without any treatment and causes no damage. Retinopathy of advanced prematurity, however, can cause permanent visual problems or blindness.
In premature babies, especially those born before the 28th week, it is not completely conformed and there is a risk of a malformation with varying degrees of severity, known as retinopathy of prematurity. In general, it is irreversible, but there are two interventions that significantly reduce its incidence and, once the problem is detected in the retina of a premature baby, prevent its progression: ophthalmological control of babies born before term in the neonatology rooms and the correct management of the level of oxygen saturation when this, for not having these fully developed newborns the lungs, must be supplied artificially.
Retinopathy of prematurity is a multifactorial condition. There are multiple factors that cause the blood vessels of the retina to develop abnormally, and the [incorrect] supply of oxygen is the main one, because it can interfere with the development of the vessels. The child born prematurely needs oxygen, but if it is we supply in an excessive amount there may be problems.
The important thing is not how much oxygen the newborn aspirates, but the amount of oxygen in the blood. This saturation level is measured with a non-invasive system and must be constantly monitored in the neonatology room so that it is between 89% and 92%. “If the level is higher, you are at risk of retinopathy; if it is lower, you have other risks of poor development or mortality. If the hospital does not have the sufficient structure or there is no one who regulates it correctly, since it fluctuates over time,” says the specialist, “the oxygen saturation can remain at a very high level.”
On the other hand, the lower the gestational age and the lower the birth weight (especially in those under 1,000 grams), the risk of retinopathy increases. In those born after 28 weeks of gestation, the most important factors are infections and perinatal blood transfusions. “In centers where neonatal services are more developed, the incidence of retinopathies is lower,” said the Brazilian specialist.
As a public health problem, retinopathy of prematurity gained relevance from advances in neonatology, which allow saving the lives of babies of gestational age. Thus, it became the first cause of blindness and low vision in childhood, just where the lowest neonatal mortality was achieved: it was that it took time to discover what factors determine the development of the retina to be able to control them.