Stratification analyses on proliferative diabetic retinopathy (PDR) and non-proliferative diabetic retinopathy (NPDR) were also conducted for seven genetic variants: Ins/Del variant at ACE gene; SNP rs759853 at AKR1B1 gene; SNPs rs1570360, rs2010963, rs3025039, rs699947, and rs833061 at VEGF gene. The gene discussed is ACE; the disease is proliferative diabetic retinopathy.