An allergic reaction is simply the overresponse of the immune system to a specific stimulus, usually environmental. This stimulus is called an antigen. There are 4 basic types of allergic reactions. We are all very familiar with the type 1 response. This reaction is seen as a result of hay fever, bee stings, cats, dogs, or even medications. It is the cause of the itchy, watery eyes, and runny nose many of us experience each spring when we cut the grass or stroll through the park. A brief look at the cause of this response will help us better understand the treatment of these conditions.
The allergic process begins when the body first comes in contact with an antigen, pollen for example (Figure 6-1). The body then produces cells, called antibodies, to target this specific antigen. The next time the body comes in contact with the pollen, these antibodies are activated. The antibodies attach to certain cells, called mast cells, and the process of degranulization begins. When a mast cell degranulates, many substances are released. One of these substances is called histamine. Histamine and other biochemicals spread throughout the body, including the eye. Certain receptors await the arrival of histamine. When the histamine attaches to a receptor (like a key fits a lock), swelling, tearing, redness, and itching result.
The best solution to the allergy problem is to stop the cycle. The most successful way to do this is to simply eliminate the cause, or antigen. Most of the time, however, it is very hard to identify the antigen, and even if we can, we cannot avoid it. Tear supplements, such as artificial tears, are useful in allergic conjunctivitis because they help to flush the antigen away from the ocular surface. Cold compresses help to decrease swelling and slow the immune response.
• The best way to eliminate allergies is to avoid the cause—not always an easy task.
• Cold compresses can help to relieve symptoms of allergies.
Medically, mild to moderate allergies are handled at 3 different levels. At the lowest level, ocular decongestants constrict the superficial blood vessels and decrease associated redness. Further up the allergic response, antihistamines can be used to block histamine receptors and reduce the resulting symptoms. Antihistamines are not always effective because other biochemicals also cause allergic symptoms. Lastly, drugs called mast cell stabilizers prevent the initial process of degranulation from occurring. In this chapter, we will look at drugs from each of these levels.
Ocular decongestants, or vasoconstrictors, are useful in decreasing the redness and irritation of mild allergies. When administered topically, they constrict the superficial conjunctival blood vessels and, thus, reduce congestion and redness. These agents have no effect on the deeper episcleral vessels. Vasoconstriction occurs within minutes after administration of these drugs. There are currently 4 ocular decongestants available for use in cases of allergic conjunctivitis: phenylephrine, naphazoline, oxymetazoline,and tetrahydrozoline. All are available without prescription either alone or in combination with other agents (Tables 6-1 and 6-2).
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The human body And Todays chemical infested world. Here is a news flash You are not allergic to pollen, pet dander, or whatever it is that makes your body revolt Rather, your body just can not handle that one thing, what ever it is, anymore, due to the massive barrage of toxic chemicals you and everyone else are ingesting every single day.