Eye Allergy

Severe allergic eye symptoms are cause for visits to the allergist, ophthalmologist and even the emergency room and are very distressing. Sometimes resulting in visits to the emergency room, these are commonly cause for visits to the allergist and ophthalmologist. Serious eye damage caused due to allergies can threaten eyesight occasionally. Causes for allergy in eyes are along the lines of hay fever and allergic asthma and are associated with allergic conditions such as allergic rhinitis (hay fever) and dermatitis (atopic eczema). Cosmetics and medications are causes that likely cause eye allergies. Eye irritants that cause reactions are often associated with eye conditions and infections such as pink eye.

Basic anatomy of the outer eye

The outer eye involves the conjunctiva, the mucous membrane (tissue) lining covering the inner folds of the eyelids and white surface of the eyeball. Substances stimulating an allergic response cause eye allergies. When exposed to the environment, the barrier structure of the conjunctiva that is rich in blood vessels and contains more histamine releasing cells (mast cells) than the lungs has to deal with different airborne allergies.

The lacrimal tear glands located in the upper and outer portions of the eye, produce the watery component of tears which help keep the eyes moist and wash the irritants away. Immunoglobulin (antibodies) that are important immune defense components, enzymes, lymphocytes (specialized white blood cells) contained in the cornea tears is the transparent sheath in front of the lens of the eye. There is little immune activity in the cornea and no blood vessels are present.

Eyes – easy target for allergies

The conjunctiva, unlike the filtering system such as the cilia of the nose, is exposed directly to the environment upon opening the eyes. Developing similar to those in the nose, allergy symptoms that cause the antibody IgE to coat the numerous mast cells in the conjunctiva to release mediators like histamine. This produces burning, itching and runny eyes that turn red due to inflammation. Swelling of the eyelids may occur and they may even close together. Swelling with fluid, when the conjunctiva protrudes from the surface of the eye and resembles a “hive”, the situation is more serious and light sensitivity may be induced. Typically, the allergic reaction affects both the eyes and since the one infected eye when rubbed makes mast cells release more histamine.

When allergens are the cause for the reaction and inflammation caused in the conjunctiva, the situation is referred to as allergic conjunctivitis. The inflammation causes blood vessels to enlarge and this results in the eyes having a red or bloodshot appearance.