Eye allergy introduction

The eyes are the windows to the soul because they reflect our state of mind. This certainly can't be true if our eyes are red, watery, and itchy from an allergic reaction. Severe allergic eye symptoms can be very distressing and are a common reason for visits to the allergist or ophthalmologist. Occasionally, severe eye allergies cause serious damage that can threaten eyesight.

Eye allergies usually are associated with other allergic conditions, particularly hay fever (allergic rhinitis) and atopic eczema (dermatitis). The causes of eye allergies are similar to those of allergic asthma and hay fever. Medications and cosmetics can play a significant role in causing eye allergies. Eye irritants and other eye conditions are often confused with eye allergy.

What is the basic anatomy of the outer eye?

Eye allergies mainly involve the conjunctiva, which is the tissue lining (mucus membrane) 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 lacrimal (tear) glands are located in the upper and outer portions of the eye. They are responsible for producing the watery component of tears. The tears also contain important immune defense substances such as immunoglobulin (antibodies), lymphocytes (specialized white blood cells), and enzymes.

The cornea is the transparent sheath in front of the lens of the eye. The cornea has no blood vessels and very little immune activity.

allergies?

When you open your eyes, the conjunctiva becomes directly exposed to the environment without the help of a filtering system such as the cilia, the hairs commonly found in the nose.

Allergy Fact

People who are susceptible to allergic eye disease are those with a history of allergic rhinitis and atopic dermatitis and those with a strong family and/or personal history of allergy. Symptoms usually appear before the age of 30.

The scenario for developing allergy symptoms is much the same for the eyes as that for the nose. Allergens cause the allergy antibody, IgE, to coat numerous mast cells in the conjunctiva. Upon reexposure to the allergen, the mast cell is prompted to release histamine and other mediators. The result is itching, burning, and runny eyes that become red due to inflammation, and resulting congestion. The eyelids may swell, even to the point of closing altogether. Sometimes, the conjunctiva swells with fluid and protrudes from the surface of the eye, resembling a "hive" on the eye. These reactions may also induce light sensitivity. Typically, both eyes are affected by an allergic reaction. Occasionally, only one eye is involved, particularly when only one eye is rubbed with an allergen.

Allergic conjunctivitis is inflammation of the conjunctiva that is caused by a reaction to allergens. The inflammation causes enlargement of the blood vessels in the conjunctiva ("congestion"), resulting in a red, or blood- shot appearance of the eyes.

What are allergic eye conditions?

Allergic Conjunctivitis

Allergic conjunctivitis, also called "allergic rhinoconjunctivitis", is the most common allergic eye disorder. The condition is usually seasonal and is associated with hay fever. The main cause is pollens, although indoor allergens such as dust mites, molds, and dander may affect the eyes year-round. Typical complaints include itching, redness, tearing, burning, watery discharge, and eyelid swelling. To a large degree, the acute (initial) symptoms appear related to histamine release. The treatments of choice are topical antihistamine/decongestants and the newer mast cell stabilizers. Topical steroids should be used only for severe reactions on a short-term basis because of the potential for side effects. In general, oral antihistamines are the least effective option, but they are often used for treating allergic rhinitis together with allergic conjunctivitis.
Rubbing itchy eyes is a natural response. However, rubbing usually worsens the allergic reaction due to the physical impact on the mast cells, which causes them to release more mediators. Translation: Do not rub your eyes