The exact time of development of the retinal blood vessels in preterm infants is uncertain. This is because the time of birth is uncertain and there is a possibility that the vessels may become diseased and not develop fully during the developmental process. In normal infants, blood vessels reach the nasal serrations at 36 weeks and the temporal serrations at 40 weeks. If the baby is born early, i.e. prematurely, the retinal blood vessels are most likely not fully developed. During this process, if there is a history of oxygenation, the retinal vessels may stop developing or the retinal vessels may overdevelop and form neovascularization. To determine if the retinal vessels are fully developed, a funduscopic examination should be performed in a timely manner.