Risk factors and growth factors in ROP.

Retinopathy of prematurity (ROP) is a multifactorial disease which incidence is increasing with increasing survival of very preterm infants. Pathogenic pathway is characterised by abnormal retinal vascular development modulated by vascular growth factors: low IGF-1 in the first phase and high VEGF in the second phase. Many causal factors are able to influence retinal vascularization: gestational age, birth weight, oxygen administration, perinatal bacterial or fungal infections, and blood transfusions. All risk factors, both oxygen and not-oxygen-regulated, have been studied considering the whole period from hospital birth to the hospital discharge, but it is possible that postnatal risk factors may be determinant in a time-dependent way. Analysis of factors involved in the pathogenesis of ROP suggests that their action begins long before anatomical clinical features become appreciable and this is strengthened by the essential role of risk factors from the first two to four weeks of life, thus preventive strategies in very preterm infants should be carried out since birth.