 | Glaucoma: What Every Patient Should Know |  |
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| Glaucoma: What Every Patient Should Know | |
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The system that makes aqueous humor at the ciliary body is driven by a chemical (enzyme) called carbonic anhydrase. In the 1950s, two researchers at the Wilmer Institute (Tom Maren and Bernard Becker) realized that blocking this enzyme chemically would decrease the formation of aqueous and lower eye pressure. For 30 years, we had only a pill to do this with, but more recently the eye drop formulations dorzolamide (Trusopt) and brinzolamide (Azopt) were developed and work almost as well as the pills and without the general body side effects that make acetazolamide (Diamox) and methazolamide (Neptazane) pills so hard for patients to tolerate. The eye drop form has to be used twice per day, and the FDA felt that it really did best when taken 3 times per day when these were the only drops used to lower eye pressure. When patients are taking more than one drop to lower the eye pressure, it is reasonable to use this class of medicines twice a day. The pill forms of this type of medicine are taken from once up to 4 times per day. Generic dorzolamide has been a reasonable substitution for the brand name.
Possible side effects of this group of drops are that they sting more than the other glaucoma drops for minutes after being given. And, in about one in ten patients they leave an unpleasant taste in the mouth, described as metallic. Allergy is low and about as common as with beta blockers. Fortunately, there have been no reports that these drops cause the general body problems that are caused by the pill forms. For example, the pills can cause severe tiredness, mental depression, pins and needles sensation in the lips and fingers, kidney stones, and worst of all, a form of loss of all blood cells that can be severe in a very small number of persons (aplastic anemia). When we are facing a very serious, acute form of very high pressure, we still prescribe these pills for temporary periods to save vision. Some persons have taken them for years with no problems and for them they remain a good solution. These medications should be avoided in people with sickle cell disease. The pills should also be used carefully in people with a history of poor kidney function or who have a sulfa drug allergy.
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