The MANF levels were clearly lower in the vitreous samples from patients with pure proliferative diabetic retinopathy (n = 8) (2.07 ± 0.14 ng/ml) compared with those from the patients with proliferative diabetic retinopathy with vitreous hemorrhage (n = 13) (3.77 ± 0.97 ng/ml) (p < 0.01). This evidence concerns the gene MANF and proliferative diabetic retinopathy.