Abstract
Abstract: :
Purpose: To evaluate and compare Nerve Growth Factor (NGF) vitreal levels in human Proliferative Diabetic Retinopathy (PDR) and Proliferative Vitreoretinopathy (PVR). Methods: Nineteen patients were selected for the study and vitreous samples were obtained during surgery. 4 patients had proliferative vitreoretinopathy and 5 patients had proliferative diabetic retinopathy. Epiretinal membranes (ERM) were obtained from 10 patients to be used as controls. ELISA, a sensitive technique for accurately determining the amount of protein in a given sample by means of an enzyme-catalyzed color change was used to determine the amount of Nerve Growth factor in each vitreous sample by comparing against a standard curve to obtain the concentration f NGF protein in the sample. Results: NGF level was significantly elevated in the PDR samples as compared to the PVR samples and controls. The PVR samples had a mean NGF concentration of 145.58 pg/ml, PDR samples had a mean NGF concentration of 1544.56 pg/ml and the control ERM samples had a concentration of 44.28 pg/ml. The median NGF concentration in PVR and control samples was 109.08 and 32.65 respectively as opposed to a median of 1903.35 in PDR samples. NGF was low or undetectable in 2/10 controls. Kruskall Wallis and Dunn's statsitical tests revealed a statistically significant difference (p<0.05) among the three groups. Conclusion: Patients with proliferative diabetic retinopathy and vitreoretinopathy have increased levels of vitreal Nerve growth factor. Several studies have shown raised NGF levels to be associated with hypoxia. Chronic hypoxia seen in PDR may be one of the factors for the increased NGF levels observed in PDR. Following studies on a larger sample population, NGF may be used, to screen and determine the severity of proliferative diabetic retinopathy.
Keywords: 388 diabetic retinopathy • 524 proliferative vitreoretinopathy • 628 vitreoretinal surgery