Your eye has pressure just like your blood, and when this intraocular pressure increases to dangerous levels, it damages the optic nerve. This can result in decreased peripheral vision and, eventually, blindness. Glaucoma is similar to ocular hypertension but with accompanying optic nerve damage and vision loss.

Glaucoma affects an estimated 3 million Americans, with 120,000 blind due to the condition. Elsewhere in the world, glaucoma treatment is less available, and glaucoma ranks as a leading cause of blindness just about everywhere. Even if people with glaucoma do not become blind, vision can be severely impaired.

  
     
 
There are two major types of glaucoma: chronic or primary open-angle glaucoma (POAG) and acute closed-angle glaucoma. These two are responsible for most glaucoma problems, but other variations include congenital glaucoma, pigmentary glaucoma and secondary glaucoma.
 
Click on the image to see a diagram of aqueous humor buildup.
 
 
     
 
Chronic glaucoma (primary open-angle glaucoma or POAG) is often called "the silent thief of sight" because you have no warning sign, no hint that anything is wrong. About half of Americans with chronic glaucoma don't know they have it. Glaucoma gradually reduces your peripheral vision, but by the time you notice it, permanent damage has already occurred. If your IOP remains high, the destruction
 
can progress until tunnel vision    
develops, one of the final stages of glaucoma before total blindness, in which you are only able to see objects directly in front of you.
 
     
 
An acute attack of narrow-angle glaucoma, also termed acute angle-closure glaucoma or acute closed-angle glaucoma, produces sudden symptoms such as eye pain, headaches, haloes around lights, dilated pupils, vision loss, red eyes, nausea and vomiting. These signs may last for a few hours, then return again for another round. Each attack takes with it part of your field of vision.
 
 
     
 

Other signs include headaches, blurred vision, difficulty adapting to darkness, or haloes around lights. Chronic glaucoma normally develops after age 35.

Like POAG, normal-tension glaucoma (also termed normal-pressure glaucoma, low-tension glaucoma or low-pressure glaucoma) is an open-angle type of glaucoma that can cause visual field loss due to optic nerve damage, but in normal-tension glaucoma, the eye's IOP remains in the normal range.

Chronic narrow-angle glaucoma, like open-angle glaucoma, can be symptomless until vision loss occurs.

Acute angle-closure glaucoma is a medical emergency. If the high pressure is not reduced within hours, it can permanently damage vision. Anyone who experiences its symptoms should immediately contact an ophthalmologist or go to a hospital emergency room.

It's difficult to spot signs for congenital glaucoma because the children are too young to understand. If you notice a cloudy, white, hazy, enlarged or protruding eye, consult your eye doctor. Congenital glaucoma occurs more in boys than girls.

Pigmentary glaucoma often exhibits no symptoms at all. You may notice some pain and blurry vision after exercise. Pigmentary glaucoma affects mostly white males in their mid-30s to mid-40s.

  
 

 

  
 
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