Spring is in the air, and unfortunately, so are a variety of grass, tree and weed pollens that can cause annoying allergic reactions in about 20 percent of the population. Due to their recurrence at about the same time each year, they're known as seasonal allergies and usually cause annoying symptoms such as itchy, watery, red eyes, a runny nose and sneezing.

75% of allergy sufferers report discomfort with contact lens wear.

If you're one of those who suffer from allergies and you wear contact lenses, there's a good chance you've experienced some form of lens wearing discomfort. In fact, about 75 percent of allergy sufferers who wear contact lenses have experienced problems. This can be especially prevalent during peak allergy seasons. But allergies are not just a seasonal problem. Other types of allergies are chronic or year round and can be caused by dust, mould, pet dander and other environmental factors. Some people suffer from sensitivities to chemicals, as well.

What's an allergic reaction?

When you are exposed to an allergy causing substance, known as an allergen, your body's immune system treats it as a foreign invader. Normally, this natural reaction protects us from the harmful effects of viruses and bacteria. Where allergens are concerned however, the immune system actually over-reacts to a relatively harmless invader and starts producing inappropriately high amounts of histamines and other chemicals. It's this reaction that is responsible for most common allergic symptoms.

Eyes can become overly sensitive during an allergic reaction, regardless of the triggering allergen. The allergen causes the release of histamines into the eye producing symptoms such as redness, dryness, itching and in particular, tearing. Because tears contain protein, more tears means more protein and for contact lens wearers, protein can be a problem.

Protein adheres, builds up on the surface of contact lenses and becomes "denatured" or changes shape. It is this "denatured" protein that can cause irritation. This then becomes cyclical, in which the protein build-up causes more of an immune response and consequently, more irritation. In about 5 to 10 percent of soft contact lens wearers, the irritation can become so severe that giant papillary conjunctivitis (GPC) develops and lens wear becomes intolerable.

In addition, the build-up of proteins and natural oils known as lipids, can lead to areas on the lens that do not wet effectively and consequently feel dry and scratchy. This in turn leads to more tearing and more build-up and further irritation.