The first such published model is the Weight, Insulin-like growth factor-1, ROP (WINROP) algorithm.6 7 Others are Children’s Hospital of Philadelphia ROP, the Colorado ROP model, Omaha ROP and the Postnatal Growth and ROP study (G-ROP).8-11 Weight at specific postnatal days, however, is not always available to the screening ophthalmologists for all infants but necessary for the models noted above. The gene discussed is IGF1; the disease is retinopathy of prematurity.