Reduced concentrations of angiogenesis-related factors in vitreous after vitrectomy in patients with proliferative diabetic retinopathy

Background: The purpose of this study was to determine whether vitrectomy alters the angiogenic profile in the vitreous of eyes with proliferative diabetic retinopathy (PDR). Methods: We measured the levels of angiopoietin-2, HGF, bFGF, PDGF, TIMP-1, and TIMP-2 by sandwich enzyme linked immunosorbent assay (ELISA) in vitreous samples from 27 eyes of 26 patients with PDR before pars plana vitrectomy (without IOL implantation) and in 12 fluid samples from 12 patients with PDR obtained during an IOL implantation 3.5 to 9 (mean 4.9) months after an earlier vitrectomy. The levels of these factors were also measured in 12 vitreous samples obtained from 12 eyes that had undergone epiretinal membrane (ERM) or macular hole (MH) surgeries. Results: The mean vitreous levels of both angiopietin-2 (103 pg/ml) and HGF (1091 pg/ml) in the sample from eyes with PDR collected at the time of the IOL implantation were significantly lower than in those collected before the vitrectomy (P<0.01). On the other hand, the changes in the levels of TIMP-1 and TIMP-2 were both not significant after vitrectomy. Conclusion: The significant decrease of angiopietin-2 and HGF in the vitreous fluid after vitrectomy suggests that vitrectomy shifts the eye towards an anti-angiogenic environment.