Allergic eye diseases are common disorders where the conjunctiva is affected and the red eye is a distinguishing feature. But in most cases, allergic rhinitis and less frequently asthma and eczema are present. However, initially, the eye-related symptoms are most prominent.

The eye is probably most vulnerable to allergic attacks as it lacks a mechanical barrier to the entry of allergens. The practice of treating allergic eye diseases as nuisance is misguided, since the quality of life is profoundly affected. Seasonal eye allergies may cause headache, fatigue, loss of sleep and generally reduce the efficiency of the patient.

The incidence of allergy is as high as 30% to 50% in the U.S. and is higher in industrialized countries because of resulting pollution, urbanization and hygiene issues.

Classification

The most common allergic eye diseases affect people of all age groups and are:

Seasonal allergic conjunctivitis: It is often associated with hay fever and is triggered by the same allergens that cause allergic rhinitis - pollens of trees, grass or weeds. In U.S. ragweed pollen has been identified as the most common cause of seasonal allergies.

Perennial allergic conjunctivitis: It occurs throughout the year because of allergens, which are present at all times of the year. These commonly are house dust mites, molds or animal dander.

The symptoms for the above two eye allergies are itching watering and redness of the eye. Allergic rhinitis is usually present.

The rarer and more serious types of allergic eye diseases are:

Atopic keratoconjunctivitis or AKC: This is a chronic, inflammation of conjunctiva and eyelids. AKC affects both eyes and is commonly associated with a family history of atopy like, eczema and asthma. Approximately, 25% of the elderly eczema patients develop some symptoms of AKC. Although the disease generally affects people in their 50s, in some cases onset of AKC may be as early as late teens. In some ways it is a life long disease. Corneal involvement may lead to blindness. About 10% of AKC patients also report cataract with severe types of atopic dermatitis. Young adults are more prone to developing AKC, 10 years after the onset of atopic dermatitis. Uniquely, AKC affects the anterior part of the lens, making it opaque in 6 months.

The symptoms are continuous itching, soreness, loss of vision and a feeling of dryness. It is associated with eczema. Some of its symptoms are similar to those of eczema, like swollen eyelids.

Vernal keratoconjunctivitis or VKC: VKC is a rare chronic disease, affecting both eyes, and occurs in children with a history of atopy. Before puberty, it occurs more in males. After puberty, males and females are equally affected. VKC recurs in spring with symptoms that are triggered by wind, dust, and hot weather or sweating caused by physical exertion. In 5% cases, VKC may lead to blindness, with one eye affected more than the other.

The symptoms are watering of the eyes, stickiness, itchiness and stuck eyelids after sleep. Corneal involvement may cause pain, loss of vision and sensitivity to light.

Giant papillary conjunctivitis or GPC: GPC is not a true eye allergy but a mimicking of eye allergy symptoms. This disease is the result of damage caused to the eye by a foreign body, such as, contact lens. Cobbles develop inside the upper eyelid, along the line of contact with the foreign body, for example, the edges of the contacts. In fact, the incidence of GPC has shown an increase with the increased use of contacts. GPC often completely resolves on removal of the foreign body or contact lens.

Common symptoms include intense itching, blurred vision, increased mucus discharge and reduced tolerance to contact lens wear.

Treatment

The diagnosis is based mainly on the medical history of the patient and ophthalmologic findings. Allergy skin tests and allergy blood tests may be done to confirm the diagnosis or to detect the offending allergen.

Contacts, if worn, must be removed. If there is inflammation, cool compresses and artificial tears can be very soothing. For the seasonal or perennial allergies a dust free, less polluted area can improve things. Further change your towels and bed linen.

However medication is necessary. Drugs recommended are topical antihistamines and mast cell stabilizers. Oral histamines provide relief, especially, when allergic rhinitis is present.

In severe cases, topical steroids are used but only after a thorough diagnosis. Generally steroids are avoided because they may lead to further complications like, cataracts, glaucoma and other infections.

A severe allergic reaction, though rare, can lead to corneal ulceration, affecting the patient’s life.