The goal in preventing and treating the risk of glaucoma, or the presence of glaucoma, is to lower the pressure in the eye which we refer to as the intraocular pressure (IOP).
Glaucoma is defined as damage to the optic nerve. Glaucoma is not defined as elevated eye pressure. In most patients, the cause of the nerve damage (glaucoma) is the fact that their eye pressure becomes higher than is safe for their eye. In general, we believe that the normal eye pressure ranges from 12mm Hg to 20mm Hg. Most patients who are not at risk for glaucoma and who do not have glaucoma usually have pressures in this range (12-20mm Hg). Most patients (75%) who are at risk for glaucoma have eye pressures above this range (usually above 20mm Hg) on a routine basis. In these patients, we generally recommend that the patient lower their eye pressure using medications in the form of eye drops. There is a minority of patients (25%) who are at risk for glaucoma but who do not reveal elevated eye pressures. These patients are said to be at risk for “Normal Tension Glaucoma or Low Tension Glaucoma, both are names for the same condition. In these 25% of glaucoma sufferers, the eye pressure does not become elevated yet they appear to be at risk for glaucomatous damage.
The treatment for both types of glaucoma patients (those with high eye pressures and those with normal eye pressures) is the same. The goal of treatment is to lower the eye pressures to the low end of normal. Thus, although eye pressure is the greatest risk factor for glaucoma, there are clearly other events which contribute to the risk of glaucoma.
When you see your eye care professional, they can help you determine if you have or are at risk for one of these types of glaucoma.