Functional Defects Caused by Glaucoma – Associated Mutations in Optineurin

Glaucomas are a heterogeneous group of optic neuropathies characterized by progressiveloss of retinal ganglion cells (RGCs) leading to visual field defects. The distinctive pattern ofoptic nerve degeneration results in glaucomatous cupping. The atrophy of optic nerve cellsinitially leads to loss of peripheral vision and visual field loss increases with increased dam‐age to optic nerve. Worldwide glaucoma is the second leading cause of blindness affectingmore than 70 million people [1, 2]. Traditionally elevated intraocular pressure (IOP) is con‐sidered as a major risk factor for glaucomatous neuropathy. In addition to increased IOP,other risk factors include age, genetic and environmental factors, myopia, primary vasculardysregulation and hypertension [3, 4].Glaucoma has been classified into different types based on various criteria. One of the wide‐ly used classifications depends on the nature of iridio-corneal angle [5]. Primary open angleglaucomas (POAGs) are the most common and clinically well defined subsets of glaucomasamong Caucasians [6]. As its name suggests, in POAG there is no anatomical hindrance tothe flow of aqueous humor as the angle structures remain ‘open’. However, the drainage ofhumor is still inefficient resulting in an increase in IOP. Based on the age of onset, POAGcan be juvenile (5-35 years) or adult onset (onset after 45 years) [6]. POAGs are usuallychronic and largely asymptomatic, with gradual elevation of IOP and consequent visualfield loss. In a significant fraction of POAG, glaucoma occurs even in the absence of eleva‐tion of IOP. These are recognized as normal tension glaucomas (NTG) [7].