The association between systemic vascular endothelial growth factor and retinopathy of prematurity in premature infants: a systematic review

Retinopathy of prematurity (ROP), a vasoproliferative disorder exclusive to premature infants is an important cause of childhood blindness. The number of premature infants surviving with this condition is expected to increase globally. Animal models of oxygen-induced retinopathy studies have shown vascular endothelial growth factor (VEGF) to be a key player in the pathogenesis of ROP. This has led to increased use of VEGF antagonist as an alternative treatment for ROP. The purpose of this systematic review is to determine the association between VEGF and ROP in human newborn. The literature review identified 12 studies to date which fulfilled the search criteria. Investigators used cord blood, serum, plasma and tissue samples to investigate the association between ROP and VEGF. Studies that measured VEGF in cord blood found mixed results, with low VEGF (at birth) associated with ROP in one study and no difference noted in two others. Mixed results were also seen in studies determining VEGF in postnatal venous samples. Four studies showed no difference in VEGF level between premature infants with and without ROP, one study showed an increased VEGF level in premature infants with ROP and another study found serum VEGF to be low in premature infants with ROP. The most recent study demonstrated an initial increase in serum VEGF followed by a decline at the time of treatment. These contradictory results indicate that we are yet to fully understand the role of VEGF in human premature infants and question the rationale of treating ROP with anti-VEGF. Anti-VEGF therapy results in systemic effect on serum VEGF levels for up to 2 months and this could have an effect on neurodevelopmental outcome. The effect of this on other developing organs is currently unknown. More studies are required to determine the mechanistic relationships between systemic VEGF and ROP in premature infants.