IGF1 and retinopathy of prematurity: The main limitation of the study is that although our initial studies included patients with proliferative and non-proliferative ROP (27, 28), allowing us to determine an IGF1 cut-off point for the risk of developing the disease, in the current validation of the screening method in children over 28 weeks, no proliferative ROP has been detected, so we cannot assure its validity in these patients, although we understand that if it is capable of detecting the mild and incipient forms of the disease, it should also be able to detect serious forms.