Comparisons of PGC-1α, vascular endothelial growth factor (VEGF) and angiopoietin 2 levels in vitreous samples from patients with proliferative diabetic retinopathy (PDR) and nondiabetic patients with rhegmatogenous retinal detachment (RD). The gene discussed is PPARGC1A; the disease is proliferative diabetic retinopathy.