Think of it as a clogged sink. If the water drains too slowly through the clog, the water accumulates in the sink and eventually overflows if the faucet is left on. To keep this from happening, you can unclog the drain to let the water flow out, or you can turn off the faucet. This can cause someone who has glaucoma to eventually go blind. At first, there are no symptoms.
Vision stays normal, and there is no pain.
However, by the time glaucoma has caused severe damage, the affected person may notice that their side vision is gradually failing. This means that objects in the front may still be seen clearly, but objects to the side may be missed. As glaucoma worsens, the field of vision narrows and blindness results. More than two million people in America have glaucoma. Recent studies show that of those people, glaucoma is eight times more common in African-Americans than in Caucasians.