Glaucoma is one of the most common causes of blindness in the United States, along with cataracts, diabetic retinopathy, and macular degeneration.

Glaucoma is a disease of the optic nerve where there is a progressive loss of neurons usually related to high pressure within the eye (elevated intraocular pressure or IOP over 21 mm of mercury). In a subtype of glaucoma called normal tension glaucoma, vision loss can occur with IOP’s less than 21. This type of glaucoma can be more difficult to diagnosis since low pressures can mask the diagnosis.

If the nerve is damaged beyond a certain point, the quality of vision suffers. The loss is irreversible. Visual loss in glaucoma has been described as silent and insidious.

There are two main categories of glaucoma, open angle and narrow angle, and many varieties and subtypes of these. In narrow angle glaucoma an acute attack can occur and the pressure can rise dramatically causing pain, redness, and blurred vision from clouding of the cornea. These attacks must be treated promptly with eyedrops, laser or surgery to avoid optic nerve damage or blindness.

The left image (right eye) shows a normal optic nerve. The right image (left eye) has moderately advanced glaucoma