Elevated γ-Aminobutyric Acid, Glutamate, and Vascular Endothelial Growth Factor Levels in the Vitreous of Patients With Proliferative Diabetic Retinopathy

Levels of glutamate potentially toxic to retinal ganglion cells are found in the vitreous of patients with PDR. Elevated vitreous GABA may reflect amacrine cell dysfunction and underlie electroretinographic oscillatory potential abnormalities seen in diabetic retinopathy. The correlations of glutamate and GABA levels with an elevated VEGF level provide biochemical support for ischemia-induced neovascularization in patients with PDR. These findings present opportunities for novel therapeutic modalities in the treatment of PDR.