What is allergic eye disease?
Allergic eye disease is very like other allergies such as hayfever, asthma and eczema in which there is an excessive immune reaction to something in the environment.
Types of allergic conjunctivitis
There are three common types of allergic conjunctivitis:
- Acute allergic conjunctivitis
- Chronic allergic conjunctivitis
- Giant papillary conjunctivitis
Acute allergic conjunctivitis
This quite spectacular reaction typically occurs in children playing in long grass or with pets. The eyes are very itchy and watery, and eyelid swelling is common. Most cases resolve spontaneously within a few hours. The best treatment is cool compresses.
Chronic allergic conjunctivitis
There are three types of chronic conjunctivitis:
- Hayfever conjunctivitis
- Drug induced conjunctivitis
- Vernal keratoconjunctivitis
This is the most common type of allergic conjunctivitis. The main symptoms are itch and watering. They begin abruptly after exposure and resolve soon after exposure ceases. Symptoms may be seasonal or occur year round. The eyelids may swell and darken, an appearance known as an “allergic shiner”.
Most sufferers are only too familiar with what causes their conjunctivitis. Common triggers include:
- Seasonal allergic conjunctivitis – grass and tree pollens
- Perennial allergic conjunctivitis – animals, house dusts and mould
Drug induced conjunctivitis
Every eyedrop and ointment can cause an allergic response; either from a reaction to the drug itself or the preservative solution used to keep the bottle sterile.
The reaction may occur within a few days or after many months of treatment. Patients typically complain of non-specific irritation and low-grade itch.
Vernal disease is a severe allergic conjunctivitis that usually occurs in patients with other allergies. In adults the disease is called atopic keratoconjunctivitis.
Symptoms typically begin in spring and are often severe. The eyes are extremely itchy, watery, ‘burning’ and very sensitive to light. In severe cases vision is reduced.
Giant papillary conjunctivitis
This much less common disease affects contact lens wearers and patients with artificial eyes. Large, cobblestone-like papillae form on the inner surface of the upper eyelid.
How is it diagnosed?
Allergic eye disease is usually diagnosed by considering two things:
- The symptoms described by a patient
- Changes in their conjunctiva, eyelid and cornea
Patients with allergic eye disease complain of one or more of the following:
- Itch. This is the most important symptom of all. If there is no itch, it’s almost certainly not allergy. If there is itch, allergy is almost always present.
- Swelling of the conjunctiva and eyelids
Changes in the eye and eyelids
The signs of allergic eye disease include:
- Lid swelling
- Dark rings around the eyes (“allergic shiners”)
Tests for allergy
It is very unusual to specifically test for an allergic response. Most patients quickly identify what causes their allergy.
Patch testing has quite limited value in making the diagnosis, changing the severity of the disease or the way a patient is treated. Most individuals can’t avoid the allergen to which they are sensitive.
Distinguishing allergic conjunctivitis from infective conjunctivitis
Several features help distinguish allergic conjunctivitis from other causes of conjunctivitis. The table below gives an overview of the main differences between the two diseases.
|Allergic conjunctivitis||Infectious conjunctivitis|
|Recurrent or chronic||One-off|
|Other allergies (asthma, hayfever, eczema)||Other infection (cold or flu)|
|Watery discharge||Sticky discharge|
|Develops during day||Worse in morning|
|Lymph nodes normal||Swollen lymph nodes|
Treatment of allergic eye disease involves:
- Avoiding known causes
- Simple home remedies
- “Over-the-counter” medicines
- Prescription medicines
- Specialist only medicines
Avoiding known causes
Wherever possible sufferers should avoid any known causes of allergy. Simple measures include:
- Changing play areas
- Hand washing after work or play
- Staying indoors when pollen or dust levels are high
- Closing windows
- Delegation of lawn mowing
- Removal of plant species
- Goggles and wrap-around sunglasses
- Dust covers on pillows and mattresses
- Exposing furniture to sunlight to kill dust mites
- Removal of carpet
- Selling the cat/dog/rabbit/horse
- Moving house
Two simple treatments can be very effective:
- Irrigating the eyes with artificial tears or solutions such as Optrex.
- Cool compresses can provide excellent relief, particularly in children with acute allergic conjunctivitis. The simplest way to do this is keep a wet flannel in a plastic bag in the fridge.
Over-the-counter (OTC) treatments
There are several types of treatments available without prescription from a pharmacy. Note that oral (tablet form) antihistamines are almost always ineffective.
The most effective OTC medicines are:
- Topical antihistamines
- “Whitening” agents
These are useful if symptoms occur infrequently or in a predictable way; for example when mowing the lawns. These drops can be used either when symptoms develop or before starting the activity associated with allergy.
Commonly used agents include:
- Livostin (levocabastin)
- Lomide (lodoxamide)
This type of drug constricts the blood vessels of the conjunctiva. The main effect is to whiten the eye and there is some relief of itch and watering.
More potent eyedrops are available on prescription. The two most effective medicines are:
- Cromolux (sodium chromoglycate)
- Patanol (olopatanol)
This is a very effective drug that often fails because treatment is stopped before it gets a chance to work. The drug takes three weeks to take effect and must be used continuously for ongoing relief.
Patanol is simple to use and very effective in some patients.
Specialist only medicines
Patients with severe allergy usually require treatment with steroid eyedrops. Wherever possible these are used intensively for short periods and other drugs such as Cromolux are used at the same time to reduce the amount of steroid therapy required.
Steroids are very effective but have the potential to cause significant side effects such as glaucoma and cataract. For this reason steroid eyedrops are available only under the supervision of eye specialists and patients taking steroids need to be reviewed regularly by an ophthalmologist.
There are no surgical treatments for allergic conjunctivitis.
FAQs and Links
Will antihistamine tablets help?
Not usually. Most allergic conjunctivitis requires local (eyedrop) therapy.