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, swollen, 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, ophthalmologist, and even the emergency room. 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. Reactions to eye irritants and other eye conditions (for example, infections such as pinkeye) 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 (substances that stimulate an allergic response) that become airborne. It is rich in blood vessels and contains more mast cells (histamine-releasing 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, which keeps the eye moist and washes away irritants. The tears also contain important components of the immune defense 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.