The PI proposes that the anterior optic nerve is specifically susceptible to microcirculatory compromise, causing or contributing to the development of various optic nerve disorders, including glaucomatous optic neuropathy. While recognizing the crucial role of intraocular pressure (IOP) in many glaucoma patients, the PI puts forward the notion that glaucoma is more appropriately viewed as an optic neuropathy caused by a variety of factors including, but not limited to, increased IOP. Previously, the PI has detailed the microvascular anatomy (methylmethacrylate corrosion casting) of the anterior optic nerve of non-primate mammals, non-human primates and humans. This technique was extended to evaluate the vasomotor response of a variety of agents on the microvascular beds of the eye. To more fully assess the optic nerve and its microvasculature, microsphere optic nerve blood flow and optic nerve topographic analysis has been performed. By exploiting a potent vasoconstrictor peptide (endothelin-1) and a long-term delivery system, an animal model of chronic, low-grade optic nerve ischemia has been developed. With constant infusion of endothelin-1 to the perineural, retrobulbar region of the rabbit, the anterior optic nerve vasculature demonstrates dose-dependent focal vasoconstriction of the supply arterioles, significant reduction in optic nerve blood flow, and significant increase in the optic disk cup volume. Preliminary application of the model in primates has demonstrated similar findings. By employing this model, the effects of prolonged ischemia of the anterior optic nerve will be examined. This model will allow histological (including axonal counts and apoptotic labeling), functional and morphological comparison to optic neuropathies resulting form other stressors, such as elevated IOP. The model will also allow the assessment of the combined effects of optic nerve ischemia and elevated IOP. Finally, possible pharmacologic blockers of decreased optic nerve blood flow and ischemia can be evaluated.
| Fortune, Brad; Wang, Lin; Cull, Grant et al. (2008) Intravitreal colchicine causes decreased RNFL birefringence without altering RNFL thickness. Invest Ophthalmol Vis Sci 49:255-61 |
| Wang, Lin; Fortune, Brad; Cull, Grant et al. (2007) Microspheres method for ocular blood flow measurement in rats: size and dose optimization. Exp Eye Res 84:108-17 |
| Wang, Lin; Fortune, Brad; Cull, Grant et al. (2006) Endothelin B receptor in human glaucoma and experimentally induced optic nerve damage. Arch Ophthalmol 124:717-24 |
| Cioffi, George A (2005) Ischemic model of optic nerve injury. Trans Am Ophthalmol Soc 103:592-613 |
| Fortune, Brad; Wang, Lin; Bui, Bang V et al. (2005) Idiopathic bilateral optic atrophy in the rhesus macaque. Invest Ophthalmol Vis Sci 46:3943-56 |
| Cioffi, George A; Wang, Lin; Fortune, Brad et al. (2004) Chronic ischemia induces regional axonal damage in experimental primate optic neuropathy. Arch Ophthalmol 122:1517-25 |
| Fortune, Brad; Bui, Bang V; Morrison, John C et al. (2004) Selective ganglion cell functional loss in rats with experimental glaucoma. Invest Ophthalmol Vis Sci 45:1854-62 |
| Wang, Lin; Dong, Jin; Cull, Grant et al. (2003) Varicosities of intraretinal ganglion cell axons in human and nonhuman primates. Invest Ophthalmol Vis Sci 44:2-9 |
| Cull, Grant; Cioffi, George A; Dong, Jin et al. (2003) Estimating normal optic nerve axon numbers in non-human primate eyes. J Glaucoma 12:301-6 |
| Wang, Lin; Cioffi, George A; Cull, Grant et al. (2002) Immunohistologic evidence for retinal glial cell changes in human glaucoma. Invest Ophthalmol Vis Sci 43:1088-94 |
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