IGF-1 has been a target candidate gene of genetic association studies for numerous human diseases and characteristics such as diabetes, diabetic retinopathy (DR), cancer susceptibility, osteoarthritis, body weight, growth, menarche, and longevity. 19 It has been implicated in ocular diseases such as proliferative DR, retinopathy of prematurity (ROP), and age-related macular degeneration (AMD). 20?