Glaucoma

Glaucoma is defined as a disturbance of the structural or functional integrity of the optic nerve that causes characteristic changes in the optic nerve leading to permanent defects in the visual field. If left untreated, it can lead to blindness. Glaucoma is the leading cause of irreversible blindness throughout the world and is second only to macular degeneration in the USA. Amongst the risk factors, elevated intraocular pressure, thin corneal thickness, increasing age, and a large cup-to-disc ratio are established. Concerning its pathogenesis, mechanical and vascular theories are fundamental. In addition, many other mechanisms contribute; such as immune factors, apoptosis, glutamate-induced excitotoxicity, free radicals, nitric acid synthase, and genetic mutations. To assess glaucoma; tonometry, gonioscopy, examination of optic disc, and visual field testing are essential. Animal models for glaucoma have been used to study the pathophysiological basis of glaucoma, aqueous humor dynamics, the trabecular meshwork, the ciliary muscle, and retinal ganglion cells. Animal experiments have provided a worthwhile means of evaluating diagnostic modalities and treatments, both medical and surgical.