While most people associate allergies with runny noses, sinus congestion, hacking and sneezing, in fact allergies can affect various organs, including the eyes. Because the eyes are often a significant component of your allergies, they deserve specific attention and treatment.
Those who have ocular allergies know that itching is the primary source of discomfort. Other common symptoms include redness, lid swelling, tearing, light sensitivity, "grittiness" and swollen eye. If you have dryness, stinging and the feeling that there is a foreign body in your eye, on the other hand, you likely have dry eye syndome.
But beyond being annoying, ocular allergies may be disabling. Allergic symptoms typically occur when allergy sufferers are in situations that put them in close contact with allergens to which they are sensitive, such as mowing the lawn, spending time outdoors or playing with pets. Thus, it can affect one's ability to engage in these activities, as well as affect one's efficacy at work and school. Beyond activities, however, appearance issues become a major quality of life factor. For allergy sufferers, the appearance of red eyes and puffy eyelids can be bothersome because it gives the appearance of fatigue or perhaps even illness or substance abuse.
Dry eye sufferers typically feel "tired eyes." Their symptoms affect them most in computer work, reading or TV watching.
Eye allergies are anything but rare. In the United States, an estimated 20 percent of the population suffers from them, and the incidence appears to be on the rise. Some researchers believe that our increasingly clean, modern society—which no longer requires our bodies to fight off multiple childhood infections—has caused our immune systems to shift from an infection-fighting stance to more of an allergic stance. (Infection-fighting and allergies are opposites as far as the immune system is concerned). When the body's immune system becomes sensitized and overreacts to substances such as seasonal pollens and pet allergens, an allergic reaction can occur whenever they come in contact with your eyes.
So while many people enjoy the spring and fall, millions of others frequently live in dread of those times when the trees, grass and weeds begin to pollinate. People who are sensitive to these allergens experience seasonal allergic conjunctivitis, the most common type of eye allergy. Conjunctivitis refers to a part of the eye called the conjunctiva that becomes inflamed when triggered by an allergen. All the signs and symptoms of allergy—itching, redness and tearing, as well as inflammation—occur when someone who is sensitive is exposed to allergens such as pollens, molds, house dust mites, animals and insects.
The reason the eyes are so sensitive to these substances is that they, like the skin, are exposed, unprotected surfaces that are especially vulnerable to allergens and other irritants. Allergens cause cells in the eye, called "mast cells," to release histamine and other substances or chemicals that cause blood vessels to dilate, mucous membranes to itch, and the eyes and eyelids to become inflamed. Tearing may also occur. Symptoms can range from mild eye annoyance to severe itching with major effects on the tissues inside the eyes. When the blood vessels expand, this allows for a greater flow of inflammatory and allergic molecules from the bloodstream into the eye, the site of the allergic reaction. This causes the redness and swelling of the eye. The itching is induced by a separate action of histamine binding to nerve cell receptors inducing the sensation of intense itching.
To avoid allergens, some patients have to stay indoors and lose time from school or work. Yet taking shelter is not always the answer, as some allergens reside indoors, and avoidance is not feasible for someone who must go about some daily activities outdoors. Pet dander, dust mites and molds are all common indoor allergens that can trigger symptoms for some people year round, causing perennial allergic conjunctivitis.
There are several more severe, although rare, forms of allergy, such as atopic keratoconjunctivitis (AK) and vernal keratoconjunctivitis (VK). These conditions may lead to corneal ulcers. However, the vast majority (80 to 90 percent) of eye allergies are caused by seasonal and perennial allergic conjunctivitis.
Ocular allergies may be further classified as either acute or chronic. An acute reaction occurs with intermittent exposure to an allergen, such as is often the case with seasonal allergic conjunctivitis, which may occur only at the height of pollen season. Chronic reactions occur with persistent exposure to allergens and are more likely to occur in perennial allergic conjunctivitis.
http://www.healthywomen.org/healthtopic ... rallergies
