Allergic eye disease
Description, Causes and Risk Factors:
Alternative Name: Allergic conjunctivitis.
Allergic eye disease is a broad term that encompasses several different types of eye conditions. All of these conditions involve irritation and inflammation of the conjunctiva. The most common conditions---seasonal and perennial allergic conjunctivitis---are mostly uncomfortable; however, the less common types of allergic eye diseases can be more serious and sight-threatening.
Eye allergies mainly involve the conjunctiva, which is the tissue lining that covers the white surface of the eyeball and the inner folds of the eyelids. The conjunctiva is a barrier structure that is exposed to the environment and the many different allergens that become airborne. It is rich in blood vessels and contains more mast cells than the lungs.
The most common allergic eye diseases affect people of all age groups and are:
- Seasonal allergic conjunctivitis: It is often associated with hay fever and is triggered by the same allergens that cause allergic rhinitis - pollens of trees, grass or weeds. In U.S. ragweed pollen has been identified as the most common cause of seasonal allergies.
- Perennial allergic conjunctivitis: It occurs throughout the year because of allergens, which are present at all times of the year. These commonly are house dust mites, molds or animal dander.
- Vernal keratoconjunctivitis (VKC).
- Atopic keratoconjunctivitis.
- Giant papillary conjunctivitis (GPC).
In general, an allergy is a complex disorder. Simply put, an allergic response is any unwarranted overreaction of the body's immune system to foreign substances (allergens), which the body perceives as a potential threat. These allergens vary depending on each individuals' unique immune system. The allergic reaction process is set in motion by IgE antibodies that are fixed to the surface of mast cells.
When the IgE encounters the allergen the cell membrane of the mast cell ruptures causing degranulation of the mast cells. The mast cell dumps chemical markers, known as histamine, into nearby tissues stimulating a variety of changes. The type of histamine receptors in the eye and adnexa (surrounding tissue) that stimulates dilated arterioles and veins (red eye) is called H3. The H1 receptor mediates itching and some vasodilation (redness).
The following allergens are commonly found in allergic eye disease:
- Pollen (hay fever).
- Animal fur.
- Eye drops.
- Dust mites.
The following symptoms are most typical for allergic eye disease
- Eyes become red/pink - by far the most common symptom. The eyes become irritated as the capillaries (small blood vessels) in the conjunctiva widen.
- Pain - some people have pain in one or both eyes. If the eyes are very red and painful it is important to see a doctor. Any patient with painful, red eyes, and has become sensitive to light (photophobia), and feels his/her vision is affected should see a doctor straight away.
- Itchiness - as the eyes are irritated they may itch. The itch may worsen if you keep rubbing them.
- Swollen eyelids - the eyelids may puff up when the conjunctiva becomes inflamed, or if the sufferer has been rubbing them a lot.
- Soreness - the inflammation may make the whole area feel sore and tender. Some people say the soreness feels like burning.
The diagnosis is based mainly on the medical history of the patient and ophthalmologic findings. Allergy skin tests and allergy blood tests may be done to confirm the diagnosis or to detect the offending allergen.
Treatment is usually “aimed” at stabilizing the mast cells and preventing the release of histamine. Ocular allergy treatment often requires a multi-prong approach:
- Avoid allergens.
- Treat topically.
- Avoid over the counter (OTC) vasoconstrictors.
- Regular use of anti-allergy eye drops such as sodium chromoglycate, nedocromil, olopatadine and lodoxamide can help to treat mild seasonal disease.
- Non-sedating oral antihistamines - cetirizine, loratadine, mizolastine and fexofenadine - can also help, especially when there's an associated nasal allergy.
- Corticosteroid eye drops occasionally have to be used for more severe eye allergies, but this should be for short periods only.
- Avoid the allergen - if pollen levels are high stay indoors and close all windows. If you go out wear a wrap around your glasses or sunglasses. If your pillows have feathers, consider changing them for materials you know you are not allergic to. Steps to lower the number of dust mites in the home can sometimes control dust mite allergy.
- Contact lenses - do not wear them until symptoms have cleared up completely. If you have used any medication on the eyes, wait 24 hours after treatment has ended before wearing contact lenses.
- Rubbing the eyes - the less you rub your eyes the better. Rubbing the eyes may cause the inflammation to get worse. This is easier said than done - itchy eyes makes you want to rub them.
- Bathing the eyes - use a flannel soaked in cold water. Some people say that immersing their face in clean warm water and opening the eyes help - others most definitely do not.
Disclaimer: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.
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