What is the definition of glaucoma?

An early instrument to measure IOP
An early instrument to measure IOP

From the early 1880’s until the last quarter of the 20th century, glaucoma was defined as “pressure within the eye higher than the statistical normal of the population.”

It was believed that this elevated intraocular pressure (IOP) would cause a certain type of damage to the optic nerve, which would eventually cause blindness if left untreated.

However, most eye doctors now agree that glaucoma is actually a series of conditions, characterized by a particular form of optic nerve damage that is often, but not always, associated with elevated IOP.

The American Academy of Ophthalmology now defines glaucoma as “a group of diseases with certain features including an intraocular pressure that is too high for the continued health of the eye.” So we have moved from thinking of elevated intraocular pressure as the only damaging factor in glaucoma to thinking of it as one factor in the damage caused by glaucoma. However IOP is still the main treatable aspect in glaucoma therapy.

While it is clear that elevated intraocular pressure is a risk factor for optic nerve damage, the mechanism that causes optic nerve damage is not yet clear.

Last reviewed on August 27, 2012

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