Glaucoma is a group of eye conditions that cause damage to the optic nerve, most often because of high intraocular pressure. Intraocular pressure is the fluid pressure inside the eye. Glaucoma is known as “the silent thief of sight” because there are often no symptoms until the condition is so advanced that vision loss has already occurred. In the U.S. glaucoma is the leading cause of preventable blindness. When caught early, however, glaucoma can be controlled. Regular eye exams are crucial for early detection, especially for those over the age of 50, have a family history of glaucoma, are diabetic, African American or very nearsighted.

Open-angle glaucoma, the most common type of glaucoma, occurs when the drainage angle of the eye becomes less efficient over time. This causes the pressure to build inside the eye, damaging the optic nerve. There are usually no noticeable symptoms until enough damage has been done for vision loss to become noticeable. If not treated, all of the optic nerve fibers can die, resulting in blindness.

Closed-angle glaucoma is less common and occurs when the iris is too close to the drainage angle. When this is the case, the iris can actually get sucked into the drainage angle and block it. This causes the pressure to build and is known as an acute closed angle glaucoma attack. This happens suddenly and most be treated quickly to prevent severe damage to the optic nerve.