Optic Nerve Metabolism and Ocular Blood Flow

Glaucoma is associated with many risk factors, especially elevated intraocular pressure (IOP), but also older age, a family history of glaucoma, African ancestry, diabetes mellitus and vascular diseases. It is generally believed that ischemia plays an important role in the pathogenesis of glaucomatous optic nerve damage, but the mechanisms of how the ischemia occurs and causes retinal ganglion cell death is unknown. However, both ischemia and the cell death are associated with increased concentrations of glutamate and lactate in the vitreous fluid. Dr. Lee and her team are measuring these concentrations noninvasively in vivo using MRI and MRS (spectroscopy) scans. An animal model of ischemia is being used to evaluate the levels of lactate and glutamate in real-time using MRI, MRS, fluorescein fundus angiography and scanning laser Doppler flowmetry. It is hoped that the results will lead to a better understanding of the roles of glutamate and lactate in the ischemia and retinal ganglion cell death of glaucoma.