Hong Kong Ophthalmological Society

Allergic conjunctivitis is a common eye disease. The allergic reaction is usually triggered by allergens or other factors. Typical symptoms include eye discomfort, redness, itching, tearing, warmth and fear of light. Rarely, severe allergic conjunctivitis may result in complications e.g. corneal damage leading to visual impairment.

Allergic conjunctivitis is classified into 5 types.

Seasonal allergic conjunctivitis, SAC
Perennial allergic conjunctivitis, PAC
Atopic keratoconjunctivitis, AKC
Vernal keratoconjunctivitis, VKC
Giant papillary conjunctivitis, GPC

Of these 5 types, the majority belongs to the first 2 types and they are usually of milder severity.

What is seasonal allergic conjunctivitis?

Seasonal allergic conjunctivitis usually refers to allergic reactions to pollen and plant spores. Therefore, this disease has a seasonal pattern. Patients usually also have asthma and allergic rhinitis.

What is perennial allergic conjunctivitis?

Perennial allergic conjunctivitis is an allergic reaction to dust, mould or pets. Patients may also have frequent sneezing, runny and stuffy noses. These symptoms can appear year-round, hence causing severe discomfort, affecting their daily lives.

What are atopic and vernal keratoconjunctivitis?

These two types are rarely seen compared to the previously mentioned 2 conditions. Atopic keratoconjunctivitis usually occurs in patients with atopic dermatitis (skin allergy). The eyelids may also have eczema and giant papillae. The conjunctiva may be scarred and contracted. The cornea may also have ulceration, scarring or perforation. The chance of cataract and retinal detachment is higher in these patients. Vernal keratoconjunctivitis usually occurs in warm and humid conditions in teenagers. After puberty, the disease condition usually improves. These patients may additionally experience sticky eye discharge, with giant papillae on both upper and lower lids. Small white spots may be seen at the edge of the cornea and there may also be corneal ulcers or scars. This condition is more serious than the previous mentioned types, often requiring long-term use of eye medications and even operations for treatment.

What should I do if I have the above symptoms?

If you suspect you have allergic conjunctivitis, you should seek treatment from an ophthalmologist. The doctor will make clinical judgements according to your history, symptoms and clinical examination. Other information including family history of allergy, other allergic conditions, living environment and occupation are important in making a diagnosis. Different types of allergic conjunctivitis may require different medications. The doctor will prescribe according to the symptoms and response to treatment. The duration of treatment may last from months to years.

What types of treatment are available?

The treatment of both the causes and symptoms is important. Usually, treatment of the causes includes avoidance of dust, pollen or other allergens. Treatment of the symptoms is by using medication to control the allergic reactions. If serious complications occur, surgery may be needed.

Common medical treatments are:

Antihistamines – effective, longest history and most commonly used. Modern pharmacological studies have designed newer drugs with better efficacy.
Mast cell stabilizers – used in prevention, especially in seasonal allergic conjunctivitis. It has a slower onset of action and needs to be used with antihistamines.
Non-steroidal anti-inflammatory drugs
Steroids – used in severe cases.
Artificial tears – can be used to rinse away allergens, therefore relieving symptoms.

Cold compress and abstinence of contact lens use may help improve the condition.

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