The International Classification of Retinopathy of Prematurity Revisited

The International Classification of Retinopathy of Prematurity (ICROP) was published in 2 parts, the first in 1984 and later expanded in 1987. It was a consensus statement of an international group of retinopathy of prematurity experts. The original classification has facilitated the development of large multicenter clinical treatment trials and furthered our understanding of this potentially blinding disorder. With improved imaging techniques in the nursery, we are able to offer a more quantitative approach to some of the characteristics described in the ICROP. An international group of pediatric ophthalmologists and retinal specialists has developed a consensus document that revises some aspects of ICROP. Few modifications were felt to be needed. The aspects that differ from the original classification include introduction of (1) the concept of a more virulent form of retinopathy observed in the tiniest babies (aggressive, posterior ROP), (2) a description of an intermediate level of plus disease (pre-plus) between normal posterior pole vessels and frank plus disease, and (3) a practical clinical tool for estimating the extent of zone I.