Levels of vascular endothelial growth factor and platelet-derived growth factor in neovascular glaucoma eyes and their associated diathesis

Abstract

Objective To determine the intraocular levels of vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) in patients with neovascular glaucoma (NVG) and to evaluate the relationship between probable clinical diathesis and associated levels. Methods Experimental study. Fifty-four NVG eyes of 54 patients and 10 fresh healthy donor eyes for corneal transplantation as controls were selected. The levels of VEGF and PDGF in aqueous humor and vitreous liquid aspirates from them were measured. Of the 54 eyes, 17 had central retinal vein occlusion (CRVO), 22 had diabetic retinopathy (DR), 4 had retinal vasculitis (Eales disease),4 had retinal detachments (RD) and 7 had unidentified NVG (NA). Among them, the number of NVG cases with iris neovascularization grades Ⅰ , Ⅱ, Ⅲ and Ⅳ were 17, 12, 13 and 12, respectively,and 36 eyes were treated with prophylactic retinal photocoagulation and/or cryotherapy. The levels of VEGF and PDGF were measured using an enzyme-linked immunosorbent assay (ELISA) method. The differences in VEGF and PDGF levels between the NVG and control groups were analyzed with a Mann-Whitney U test. The differences in the various primary causes, in the iris neovascularization grades and between the prophylactic-treated and untreated groups were analyzed with ANOVA, LSD-t and independent samples t test, respectively. The correlation analysis between VEGF and PDGF levels in each group were checked with a Pearson test. Results The free VEGF and PDGF concentrations in aqueous humor from NVG patients were (926.3±223.5)ng/L and (226.2±81.5)ng/L and the concentrations in vitreous liquid were (1096.1±235.9)ng/L and (375.3±141.5)ng/L, which were higher than concentrations in normal control eyes (aqueous humor: ZVEGF=-4.993, ZPDGF=-4.891, vitreous liquid: ZVEGF=-4.991, ZPDGF=-4.992, all P=0.000). The free VEGF concentrations in aqueous humor and vitreous liquid from NVG secondary to CRVO were higher than those in the NA group (aqueous humor: t=1.746, P=0.033; vitreous liquid: t=1.917, P=0.027). There were no differences in VEGF between CRVO, DR, Eales, and RD eyes. The PDGF concentrations in aqueous humor and vitreous liquid from NVG with diabetic retinopathy (DR) were higher than the concentrations in NVG secondary to Eales disease (aqueous humor: t=1.697, P=0.043; vitreous liquid: t=1.762, P=0.038).There were no statistical differences between VEGF in aqueous humor and vitreous liquid among the various iris neovascularization grades. The vitreal PDGF level in iris neovascularization grade Ⅳ was higher than that in grade Ⅲ (t=1.740, P=0.049). The VEGF and PDGF concentrations in aqueous humor and vitreous liquid in NVG with previous retinal photocoagulation and/or cryotherapy were lower than those in non-intervention NVG (aqueous humor: ZVEGF=2.945, PVEGF=0.003; tPDGF=3.199,PPDGF=0.002; vitreous liquid:ZVEGF=3.165, PVEGF=0.002; tPDGF=2.984, PPDGF=0.004). Correlation analysis showed that there was a positive correlation between the VEGF and PDGF levels in aqueous humor (r=0.305, P=0.025) and vitreous liquid (r=0.303, P=0.026). In NVG secondary to CRVO, the VEGF level in vitreous liquid was positively correlated with PDGF (r=0.503, P=0.040), while the VEGF level in aqueous humor from NVG with DR was positively correlated with PDGF (r=0.462, P=0.030).Conclusion VEGF and PDGF levels are related to primary causes of NVG and iris neovascularization grading, and their release may be inhibited after retinal photocoagulation and/or cryotherapy in NVG eyes. Key words: Glaucoma,neovascular; Vascular endothelial growth factors; Platelet-derived growth factor; Neovascularization; Laser therapy