| Background:Main causes of visual impairment in proliferative diabetic retinopathy (PDR) are vitreous hemorrhage and macular edema due to intraocular neovascularization. To explore the pathogenic mechanism of neovascularization is great significance to prevention and management of PDR.Purpose:To analysis the level of vascular endothelial growth factor (VEGF) and pigment epithelium-derived factor (PEDF) in eyes with proliferative diabetic retinopathy (PDR) before and after intravitreal injection of ranibizumab.Methods:41 patients were enrolled in this study from December 2013 to November 2014 in our hospital. Twenty-five eyes of twenty PDR patients were collected as the PDR group, which included two eyes of two patients had neovascular glaucoma, rubeosis of the iris with PDR. Twenty-five eyes of twenty -one age-related cataract patients were collected as the control group. Samples of aqueous humor were collected just before and 7 days after the injection of ranibizumab in PDR group. Samples of aqueous humor were collected just before cataract surgery in control group. The concentrations of VEGF and PEDF in the aqueous humor were measured by enzyme-linked immunosorbent assay (ELISA).Results:1.The VEGF concentrations in the aqueous humor before the injection was 367.27± 151.26 pg/ml (mean±SD, n=25). Seven days later, it was 237.09 ± 42.22 pg/ml (n=25). The PEDF concentrations in the aqueous humor before the injection was 1254.00 ± 253.47 pg/ml (n= 25), and seven days later, it was 1011.50 ± 223.22 pg/ml. The VEGF and PEDF concentrations in control group were 222.54 ± 37.24 pg/ml (n=25) and 857.61 ± 155.97 pg/ml, respectively. The concentrations of VEGF and PEDF in the aqueous humor before intravitreal injection of ranibizumab in PDR group were significantly higher than the control group (Z=-5.228、4.706, P<0.05). The VEGF and PEDF concentration in the aqueous humor were reduced significantly after intravitreal injection of ranibizumab in PDR group (Z=-4.072、-4.319, P<0.05). The VEGF concentration in the aqueous humor was no significant difference between after intravitreal injection of ranibizumab in PDR group and control group (Z=-1.557, P>0.05). However, the concentration of PEDF in the aqueous humor after intravitreal injection of ranibizumab in PDR group still higher than control group (Z=-2.475,P<0.05).2. The ratio of VEGF/PEDF in the aqueous humor before intravitreal injection of ranibizumab in PDR group was 0.31 ± 0.17, and seven days later, it was 0.24 ± 0.07. Comparison the difference of VEGF/PEDF ratio before and after intravitreal injection of ranibizumab was statistically significant (Z=-2.058, P<0.05). The ratio of VEGF/PEDF in the control group was 0.27 ± 0.09, and there were no difference in the control group and PDR group (P> 0.05).3.The aqueous humor concentrations of VEGF and PEDF were not significantly correlated with each other, neither in PDR group (r=-0.195、-0.174, P>0.05) nor in control group (r=-0.286, P>0.05). The concentrations of VEGF before intravitreal injection of ranibizumab was significantly correlated with ntraocular pressure (r=0.886, P<0.05). The aqueous humor concentrations of VEGF and PEDF with age, sex, glycosylated hemoglobin, there was no significant correlation(all P>0.05).Conclusions:1. High levels VEGF and PEDF in the aqueous humor may be related to the progression of proliferative diabetic retinopathy.2. Intravitreal injection of ranibizumab significantly decrease the VEGF and PEDF in the aqueous humor after 7 days, indicating that ranibizumab have good clinical effects to anti-VEGF.3. Intravitreal injection of ranibizumab changed the ratio of VEGF/PEDF may be correlated with neovascularization regressed and VEGF and PEDF are not synchronous down-regulate. In the same time, VEGF and PEDF there may be some mutual adjustment mechanism. |
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