PURPOSE: We investigated possible correlations between vitreous and/or serum levels of platelet derived growth factor isoforms (PDGF-AA, -AB, -BB) with parameters associated with proliferative diabetic retinopathy (PDR), and compared the results to vascular endothelial growth factor (VEGF), which is an established growth factor affecting PDR.METHODS: Thirty-one patients with PDR and 15 non-diabetic patients were included in the study. Vitreous and serum samples were obtained during vitrectomy. PDGF-AA, -AB, and -BB, as well as VEGF, were measured by enzyme-linked immunosorbent assay.RESULTS: PDGF-AA, -AB, -BB, and VEGF were all expressed in serum and vitreous of controls and patients with PDR. The levels of all PDGF isoforms and VEGF in vitreous were significantly increased in the PDR group, as compared to controls. No such differences were evident in serum. PDGF-AA and PDGF-BB correlated significantly to the severity but not the activity of PDR. PDGF-AB and -BB were significantly lower in vitreous of patients with pre-performed complete panretinal photocoagulation (PRP) as compared to incomplete or without PRP. PDGF did not correlate significantly to fibrovascular tissue, on the disc or elsewhere, to long-standing vitreous hemorrhage, to tractional retinal detachment, or to posterior vitreous detachment. PDGF or VEGF in vitreous or serum of PDR patients did not correlate with the serum levels of HbA1C. There was no correlation between the vitreous and serum levels of VEGF or PDGF in patients with PDR.CONCLUSIONS: It appears that, in addition to VEGF, PDGF-AA, -AB, and -BB in the vitreous are also correlated with PDR.