Vascular endothelial growth factor in aqueous humor of patients with proliferative and non proliferative diabetic retinopathy.

Abstract

Our study involved 70 participants, divided into 3 groups; 25 in the PDR group, 25 in the NPDR group, and 20 controls.

To identify candidates who may benefit from prevention strategies, it would be useful to identify molecular markers that may help to predict the development of DR at earlier stages of diabetes. VEGF seems to be a potential candidate gene for DR.

Our study that involved three groups of candidates (Group of PDR patients-Group of NPDR patients - Group of Control non diabetic patients) showed that the aqueous levels of VEGF were significantly elevated in eyes with DR compared to normal eyes and also to NDR without clinically significant diabetic macular edema. This elevation also correlated with the severity of DR, with a moderate increase of VEGF in the NPDR with cystoid macular edema and a more pronounced increase in active PDR eyes; eyes with quiescent NPDR had lower VEGF levels, comparable to the levels in PDR eyes. NPDR without clinically significant diabetic macular edema eyes had aqueous VEGF levels closer to those of normal control eyes. DME was associated with increased aqueous VEGF levels compared to eyes without DME, but the difference was not statistically significant. The elevation of VEGF levels was parallel to the severity of DR and to the degree of retinal ischemia associated with diabetic retinopathy suggesting that the main pathogenic factor causing VEGF elevation and responsible for DR progression in our patients' eyes was retinal hypoxia.

Our study supports the general opinion that DME is caused by a local increase in VEGF. A correlation between elevated VEGF in ocular fluids and the presence of DME has been revealed by some clinical studies, suggesting that VEGF is a mediator for hypoxic inflammation. In our study, mean aqueous and serum VEGF levels were significantly higher in PDR and NPDR groups compared with controls. There was also a significant correlation between aqueous and serum VEGF levels. In conclusion, the present study showed that aqueous VEGF levels are correlated with the severity of DR and are significantly increased in patients with active PDR. These results emphasize that VEGF elevation is induced by retinal ischemia and plays a major role in the development and progression of PDR. In our study we proved that there is a cut of value of serum VEGF that predicts PDR, so we recommend that diagnosis and treatment of CME by intravitreal injection or laser photocoagulation must be accompanied by measuring serum VEGF for early detection and proper management. Even we recommend to start treatment with intravitreal injection or Laser photocoagulation for patients with NPDR when we reach that level of VEGF in serum as a preventive measure from CME.