Eye allergies, also known as allergic conjunctivitis or ocular allergies, are usually centered around the conjunctiva, the clear mucus layer that lines the outside of the eyes. The cells on the conjunctiva are similar to the cells lining the inside of the nose, which is why ocular allergies and respiratory allergies have such similar symptoms. Although eye itchiness is almost always a symptom of ocular allergies, other symptoms may include eye redness, excess tearing, blurred vision, emission of mucous from the eyes, or a burning feeling in the eye. There are various types of allergens that can trigger an allergic response that affects the eyes. Some of the most common examples are pollen, animal dander, loose grass, and dust.
There are two main types of eye allergies, seasonal allergic conjunctivitis (SAC) and perennial allergic conjunctivitis (PAC). A person who has SAC usually experiences symptoms only during one or two specific times of the year. Causes of SAC include tree pollen during the springtime, grass pollen during the summertime, or weed pollen during the fall. At all other times of the year, symptoms are almost entirely nonexistent. People with PAC, on the other hand, usually have problems with indoor allergens, such as dust mites or pet dander, and are therefore affected year round. In fact, people with PAC may find that seasonal allergens actually exacerbate their symptoms. Timing aside, SAC and PAC produce the same symptoms.
The best "treatment" for allergies is to prevent them from starting in the first place. Avoid allergens as much as possible by using air conditioning and heating filters, closing windows and doors when inside, replacing carpeting with hard floors, and removing drapes and other dust catchers. Once an allergic reaction has begun, you can use cold compresses or lubricating eye drops to reduce the symptoms. Antihistamines are also available over the counter, either in eye drop or oral form, and prescription eye drops are available for allergies that require a stronger treatment.