Also known as allergic conjunctivitis or ocular allergy, eye allergy occurs when something you are allergic to irritates the conjunctiva. This clear, delicate membrane covering the eye and the inside of the eyelid is not the only part of the eye susceptible to allergies: lid margins, the delicate tissue of the eye lids and surounding the eyes, may also be affected. Burning, itching, watery eyes caused by allergic reactions can make life miserable.
Ocular allergies can cause chronic inflammation which in turn can desensitize the cornea. When the corneas are desensitized, the blink feedback loop that triggers the lacrimal gland to produce tears is interrupted, leading to aqueous tear deficiency. Inflammation caused by allergies can also impact the tear film, leading to evaporative dry eye.
Like all allergies, ocular allergies start when the immune system identifies an otherwise harmless substance as an allergen. This causes the immune system to overreact and produce antibodies called Immunoglobulin (IgE). These antibodies travel to cells that release chemicals which cause an allergic reaction. In this case, allergic reactions include eyes that water, itch, hurt or become red or swollen.
The most common causes of allergic conjunctivitis are seasonal allergens such as pollen and mold spores. People with seasonal allergic rhinitis (hay fever) normally notice their symptoms worsen when they go outdoors on days with high pollen counts.
Indoor allergens such as dust mites and pet dander can also cause eye allergies year-round. If you suffer from this type of allergy, you may notice your symptoms worsen during certain activities, like cleaning your house or grooming a pet.
Sinus allergies can contribute to the discomfort of ocular allergies, because the sinuses can become inflamed and swollen, blocking tears from draining properly through the tear ducts.
Eye allergy symptoms can be very annoying. Unlike conditions such as pink eye, allergic conjunctivitis is not contagious. However, red, itchy, burning, and puffy eyes can be caused also by infections and other conditions that can threaten eyesight.
Eye drops and ointments, used for eye lubrication or the treat of infections, allergies, and other conditions, can also cause allergic reactions. Sometimes the preservatives in the medications cause allergic reactions; sometimes other components in the medications cause allergic reactions.
Adapted from: American Academy of Allergy Asthma & Immunology
Some individuals cannot use any artificial tears, even preservative free, on a sustained long term basis, without developing an allergic reaction or toxicity to the drops.
The treatment of dry eyes
J P Whitcher
British Journal of Ophthalmology
2004 May; 88(5): 603–604. doi: 10.1136/bjo.2003.040022 PMCID: PMC1772141
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