Glaucoma: Validated and Facile In Vivo Experimental Models of a Chronic Neurodegenerative Disease for Drug Development

Glaucoma is a neurodegenerative disorder that affects the optic nerve and the inner layers of the retina. Increased intraocular pressure is a major risk factor in the disease. Chronic elevation of intraocular pressure specifically induces the death of retinal ganglion cells. By developing animal models of the disease, the scientific community has been able to make progress in understanding the mechanisms leading to the death of retinal ganglion cells, the molecular mechanisms of the pathology, and developing new pharmacological interventions. In this report, we review and compare animal models of glaucoma. We find that the episcleral cauterization model offers many advantages over other in vivo models. Its feasibility and lack of frequent complications make it the most extensively used animal model of glaucoma. Furthermore, we discuss features related to the pathogenesis of the disease and compare it with other models of retinal ganglion cell damage (e.g. optic nerve axotomy and excitotoxicity). In the last section, we focus on drug candidates for neuroprotective treatment of glaucoma, and discuss their likely mechanisms of action.