The eye’s aqueous fluid is constantly produced and drained at a balanced rate to ensure the health of the lens and cornea. When this drainage becomes blocked, or there is an increase in aqueous fluid production, intraocular pressure (IOP) increases and glaucoma occurs. Over time, this increase in pressure can cause damage to some of the sensitive structures that receive and transmit images in the eye, including the optic nerve.
The pressure damage of glaucoma causes a gradual blurring of vision and, if left untreated, can result in total, irreversible blindness.
Initially, someone suffering from glaucoma may notice a gradual loss of peripheral (side) vision, before progressing to a complete loss of peripheral vision so that only a small area off central vision remains.
Because there are no symptoms associated with the disease in its early stages, regular eye examinations with your ophthalmologist or optometrist are important.
Although risk factors for glaucoma include heredity, diet, smoking and age, the actual cause is often unclear. Raised IOP, or IOP within the “normal” range associated with other symptoms, compounds damage caused by poor blood supply, structural weakness and disordered enzyme systems. In all cases, the resulting damage is death of retinal nerve cells and irreversible loss of vision.
Types of Glaucoma
There are several forms of glaucoma, including primary open-angle glaucoma, primary closed-angle glaucoma, and normal tension glaucoma. The most common form is primary open-angle glaucoma.
Primary Open-Angle Glaucoma
With primary open-angle glaucoma, the eye’s drainage system – called the trabecular meshwork – becomes blocked, creating a slow rise in intraocular pressure that puts pressure on optic nerve fibers.
Variants of primary open-angle glaucoma include “normal tension” glaucoma (NTG), which exists in eyes that do not tolerate seemingly normal pressure, and ocular hypertension, a condition in which intraocular pressure is high without the loss of peripheral vision.