eye disorders
Overview of Glaucoma
Introduction
Glaucomas are a group of eye disorders characterized by progressive optic nerve damage in which an important part is a relative increase in intraocular pressure (IOP) that can lead to irreversible loss of vision. Glaucoma is the 2nd most common cause of blindness worldwide and the 2nd most common cause of blindness in the United States, where it is the leading cause of blindness for Black and Hispanic people. About 3 million Americans and 64 million people worldwide have glaucoma, but only half are aware of it. Glaucoma can occur at any age but is 6 times more common among people>age 60. Glaucomas are categorized as Primary Open-Angle Glaucoma None Angle-Closure Glaucoma None See tables for classification based on mechanisms of outflow obstruction for Primary Open-Angle Glaucoma , The “angle” refers to the angle formed by the junction of the iris and cornea at the periphery of the anterior chamber (see figure). The angle is where>98% of the aqueous humor exits the eye via either the trabecular meshwork and the Schlemm canal (the major pathway, particularly in older people) or the ciliary body face and choroidal vasculature (also called the uveoscleral pathway and can make up to 50% of outflow in people younger than 30). These outflow pathways are not simply a mechanical filter and drain but instead involve active physiologic processes. Glaucomas are further subdivided into primary (cause of outflow resistance or angle closure is unknown) and secondary (outflow resistance results from a known disorder), accounting for>20 adult types. Most of the aqueous humor, produced by the ciliary body, exits the eye at the angle formed by the junction of the iris and cornea. It exits primarily via the trabecular meshwork and the Schlemm canal (pink arrows). A smaller amount drains through the ciliary body face entering the uveoscleral pathway (black arrows). In early adulthood, the ratio of drainage is approximately equal in both pathways. With aging, drainage occurs predominantly through the trabecular meshwork and Schlemm canal. 