Because insulin-like growth factor 1 (IGF-1) levels in the serum and vitreous fluid are associated with the severity of retinopathy in diabetic retinopathy, Smith et al. used OIR to analyze IGF-1 function and demonstrated that IGF-1 is required for pathological angiogenesis in ischemic retinal disease [240]. The gene discussed is IGF1; the disease is retinal disorder.