If you have seasonal allergies like hay fever, you are probably familiar with the itching and redness of eye allergies. An allergy is a reaction by the immune system to particles of something the body perceives as harmful. These particles, known as an allergen, trigger the immune system to release large quantities of chemicals to fight off the invasion.
One of the most common of these chemicals is histamine. When excessive amounts of histamine are present, we have common allergic symptoms including red, swollen, sore, and itchy eyes. The most common symptom of eye allergy is itching. Redness or swelling without itching is more likely caused by something other than an allergy.
Types of Eye Allergies
There are several different types of eye allergies. Seasonal allergy in the eyes, also known as seasonal allergic conjunctivitis (SAC), is the most common type. Conjunctivitis is swelling or infection in the membrane that lines the eyelids and outer surface of the eye. In SAC, this irritation is typically caused by airborne pollens during specific growing seasons. Allergic conjunctivitis can also be perennial or year-round. Common allergens for this condition include pet dander and dust.
Eye allergies can also be caused by medications:
• Sudden onset - Topical penicillin, bacitracin, sulfacetamide, and anesthetics are some medications that can cause very sudden symptoms including swelling of the lining of the eyes and severe itching.
• Toxic papillary reactions – Some chemicals including certain antibiotics and antiviral drops and some preservatives can cause a reaction in the tiny blood vessels in the eye that can make the white part of the eye appear red. This reaction typically occurs after taking the medication for a week or more.
• Contact reaction – Chemicals that are applied directly to the skin or eye can cause a gradual build-up of irritation. These can include topical medications as well as cosmetics.
Contact lenses can also cause an allergic reaction, either to the lens itself or to proteins that are present in the tear film between the lens and the eye. This can cause swelling, redness, itching, and mucus discharge from the eyelid. It can also result in large swellings in the upper eyelid that can prevent continued wearing of the contact lenses.
Treating Eye Allergies
Treatment for eye allergies depends on the cause of the allergy. The first step is to try to stay away from whatever is causing the allergic reaction. If you recognize that wearing contacts or using certain medications triggers your symptoms, talk to your doctor to find a solution. You may benefit from changing your lens solution or may do better with daily disposable contacts. If you are using over-the-counter medications or drops that irritate your eyes, stop using those products.
Seasonal eye allergies can often be helped by over-the-counter (OTC) oral antihistamines such as Claritin ® or Zyrtec ®. OTC eye drops are also available that contain antihistamines, decongestants, or both. Antihistamines can help with itching and swelling. Decongestants help clear up redness by shrinking blood vessels. You should not use decongestant eye drops unless you truly need them. If you use them to excess, you can cause your eyes to look red when you stop using them because the blood vessels in the eyes can become dependent on the drops.
If your eye allergies are severe or on-going, schedule an appointment with your eye care professional. Rarely, inflammation caused by eye allergies can affect eyesight. Your eye doctor can rule out conditions that can cause vision problems and may prescribe stronger medications to help control allergy symptoms.
Sources:
University of Michigan Kellogg Eye Center
American College of Allergy, Asthma & Immunology
All About Vision
About.com: Eye Allergies
PubMed Health