The Eye in General Practice

Allergic conjunctivitis is one of the commonest eye problems encountered in general practice. Most patients can be treated by their GP.

Allergic conjunctivitis

Included in this document

  • Types of allergic conjunctivitis
  • Chemosis, papillae and follicles
  • Acute allergic conjunctivitis
  • Recurrent/chronic allergic conjunctivitis
  • Investigations
  • General practice treatment of allergic conjunctivitis
  • Specialist treatment
  • Distinguishing allergic from infective conjunctivitis
  • When to refer
  • Key points
  • Tables

Types of allergic conjunctivitis

In simple terms there are two types of allergic conjunctivitis – acute allergic conjunctivitis and recurrent/chronic allergic conjunctivitis. There are then four subtypes of recurrent/chronic allergic conjunctivitis – drug induced conjunctivitis, ‘hayfever’ conjunctivitis, vernal keratoconjunctivitis or ‘spring catarrh’, and atopic conjunctivitis (essentially an adult form of vernal conjunctivitis). A much rarer form of allergic conjunctivitis, giant papillary conjunctivitis (GPC), is a disease that affects contact lens wearers and patients with artificial eyes. Because GPC is uncommon, and the patients most likely to suffer from it are usually under the care of an optometrist or ophthalmologist, it will not be considered further.

Chemosis

Fig. 1 Chemosis in acute allergic conjunctivitis. (Courtesy Dr D Peart).

Chemosis, papillae and follicles

By definition conjunctivitis is inflammation of the conjunctiva.

The signs of conjunctival inflammation vary in each individual, and with the cause and duration of disease, but some generalisations can be made.

Acute allergic conjunctivitis is characterised by conjunctival swelling or chemosis (Fig.1). Physical or chemical trauma can cause a similar reaction. Chemosis usually settles within a few hours.

Recurrent/chronic allergic conjunctivitis results in the development of papillae. Papillae are vascular structures that appear to the naked eye as soft red swellings. Small papillae give the tarsal conjunctiva a ‘goose-pimple’ appearance (Fig. 2). Medium size papillae form ‘cobble-stones’ (Fig. 3) and in extreme cases patients develop ‘giant papillae’.

It is important to distinguish conjunctival papillae from conjunctival follicles. Follicles are lymphatic structures. They are the size of a grain of rice and semitranslucent (Fig. 4). Follicles are very common in children, just like other lymphatic hypertrophy. In adults, follicles are a common sign of chlamydial conjunctivitis.

Allergic conjunctivitis

Fig. 2 Moderate papillary conjunctivitis.

Fig. 3 Severe papillary conjunctivitis.

Fig. 4 Follicular conjunctivitis.

Acute allergic conjunctivitis

This quite spectacular, urticarial reaction typically occurs in children playing in long grass or with pets. The eyes are very itchy and watery. The conjunctiva becomes very swollen, very quickly. Eyelid swelling is common. The vision is near normal. Most cases resolve spontaneously within a few hours. Prescribe cool compresses and tell the patient not to rub their eyes.

Recurrent/chronic allergic conjunctivitis

Drug induced conjunctivitis

Every topical eye medication and the preservatives added to the bottles can cause a toxic or hypersensitivity reaction. The most common causes of iatrogenic allergy are preparations containing

Allergy to eye drops

Fig. 5. Medication allergy, left eye. (Courtesy Dr M.J. Elder).

Neomycin (Maxitrol and Betnesol N) and the glaucoma medication brimonidine (Alphagan). Allergic reactions to these agents usually develops within a few weeks. Patients typically complain of non specific ocular irritation and low grade itch.

Look for an obvious localised eyelid and skin reaction (Fig. 5), low grade conjunctival hyperaemia and a mild papillary conjunctivitis. Some patients develop contact dermatitis of the eyelids.

Withdraw medical treatment if at all possible.

‘Hayfever’ conjunctivitis

This is the commonest allergic conjunctivitis, affecting up to 20% of the population. Depending on the allergen to which the patient is sensitive, they may also have seasonal symptoms (grass and tree pollens) or perennial symptoms (animal dander, house dusts and moulds).

The typical history is of recurrent conjunctivitis of abrupt onset and rapid resolution. Many patients know what allergen causes their problem, so be sure to ask. Symptoms start shortly after exposure. Patients complain principally of itch and tearing and also of burning, redness and rhinitis. Many have other forms of allergy so enquire about asthma, atopic dermatitis, food and drug allergies or urticaria-angioedema.

The vision should be normal, as the cornea is never involved. Most patients have quite mild signs, especially between attacks. Look for generalised hyperaemia, mild chemosis and a watery discharge. The conjunctiva may be slightly oedematous. Evert the upper lid and look at the upper tarsal conjunctiva. There is usually a mild papillary conjunctivitis.

Treatment is discussed below.

Vernal keratoconjunctivitis (VKC) or ‘spring catarrh’

VKC is a bilateral, seasonal conjunctivitis. It is rare in New Zealand Europeans but quite common in children and young adults of Maori, Pacific Island, African and Middle Eastern descent. There are three recognised types depending on whether the palpebral conjunctiva, limbal conjunctiva or cornea is primarily inflamed. Corneal involvement is potentially sight threatening.

Patients are usually atopic (hayfever, asthma, eczema, eosinophilia) or have a family history of atopy. Symptoms typically begin in spring and are often severe. The cardinal features are intense itching, tearing, burning and photophobia.

Check the vision and pinhole vision. VKC is both a conjunctival and corneal disease. Sometimes the patient is so photophobic that the only way to test vision is to instil local anaesthetic and test in a darkened room.

In palpebral VKC the conjunctiva is hyperaemic and slightly chemotic. Look for papillae and cobblestones. In severe cases there is usually a mucoid discharge.

Vernal limbitis

Fig. 6 Vernal limbitis. Small white, eosinophil-packed spots known as Trantas dots can be seen at the limbus in this patient.

Limbal VKC is characterised by hyperaemia, thickening and oedema of the limbal area (Fig. 6).

Corneal VKC is a severe and sight-threatening disease, so always examine the cornea and stain it with fluorescein. Dullness, scarring of the cornea or any fluorescein staining is a sinister sign that requires urgent referral to an ophthalmologist.

Patients with VKC should be referred to an ophthalmologist.

Atopic Keratoconjunctivitis (AKC)

This is essentially the adult equivalent of vernal keratoconjunctivitis. The disease is a chronic hypersensitivity, probably to airborne allergens.

The typical patient is male with atopic dermatitis and a history of VKC. The symptoms are the same as those of VKC.

Most patients have severe atopic dermatitis/blepharitis. Patients have all the signs of VKC but corneal involvement is more common and often results in corneal scarring and vascularisation. Viral and bacterial infections of the cornea are common complications. Look for signs of blepharitis, keratoconus and cataract, all common associations.

Patients with AKC should be referred to an ophthalmologist.

Investigations

Patch testing is only useful if symptoms are recurrent (more than one season) and there are also non ocular symptoms. Even then it has quite limited value in changing the severity of the disease, as most individuals can’t avoid the allergen to which they are sensitive.

General practice treatment of allergic conjunctivitis

Most allergic conjunctivitis can be treated, at least initially, by GPs. Treatment should follow a logical plan and the patient must be informed that it may take some time to control their problems. All patients with VKC and AKC should be referred to an ophthalmologist but there are a number of things a GP can do if referral is delayed and to help in comanagement of the disease.

Allergen avoidance

Wherever possible the patient should avoid any known allergen(s). Avoidance strategies are outlined in Table 1.

Simple measures

Irrigating the eyes with artificial tears or solutions such as Optrex, washes allergen from the conjunctival sac. Cool compresses can provide excellent relief, particularly in children with acute allergic conjunctivitis.

Topical agents

If the problem occurs infrequently or predictably, for example when mowing the lawns, the most useful agent is levocabastine (Livostin). Livostin can be used just before likely exposure or to treat an established attack. Vasoconstrictors such as Albalon are less efficacious but are worth trying.

Patients with frequent symptoms should be started on topical sodium cromoglycate. Sodium cromoglycate is a very good agent that often fails because it is stopped before it gets a chance to work. The drug takes three weeks to work and must be used continuously to have and retain an effect. Lodoxamide (Lomide) can be trialled if cromoglycate therapy fails.

Systemic antihistamines

These agents are usually of no help unless there are non ocular symptoms and even then they are better at helping non ocular symptoms than those in the eye.

Specialist treatment of allergic conjunctivitis

Many patients ultimately require either pulse or regular topical steroid therapy but steroids are not an alternative to simple treatments and can lead to major problems. Steroid dependency and abuse is very common in this group of patients and can cause significant side effects including glaucoma and cataract. For this reason steroids should not be prescribed by GPs without the express permission of an ophthalmologist.

A short course of steroids may be given to settle symptoms while other measures are tried. All patients should trial sodium cromoglycate as even a limited response may mean that less steroid is required to treat severe disease. As many patients/GPs are unaware of the time needed to achieve a response to sodium cromoglycate, treatment with this agent is often retried.

Distinguishing allergic conjunctivitis from infective conjunctivitis

Patients with allergic conjunctivitis complain principally of itch or ‘difficulty leaving my eyes alone’ whereas those with infective conjunctivitis typically complain of a foreign body sensation or grittiness. Allergic symptoms usually develop over the course of the day. In contrast the symptoms of infective conjunctivitis are normally worse first thing in the morning and the eyelids are often gummed together on awakening. In viral conjunctivitis, small conjunctival haemorrhages are common. Tenderness and swelling of the preauricular nodes is almost pathognomonic of viral conjunctivitis. Bacterial conjunctivitis is characterised by purulent discharge.

When to refer

Refer all patients with decreased vision that does not improve with a pinhole and patients with any evidence of corneal involvement. Most patients do not need referral to an ophthalmologist unless they fail to respond to simple measures and treatments.

Key points

Most allergic conjunctivitis can be treated by GPs, but patients with signs of corneal involvement need urgent review by an ophthalmologist. The key features in the history and examination are symptoms of itch and the presence of papillae. Most chronic allergic conjunctivitis is helped or cured by sodium cromoglycate, but this drug takes three weeks to work.

Tables

Table 1. Allergen avoidance strategies
Changing play areas
Hand washing after play
Staying indoors when pollen/dust levels high
Closing windows
Delegation of lawn mowing
Removal of plant species
Air conditioning/filtering
Goggles and wrap-around sunglasses
Wet dusting
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
Table 2. Treatment strategies
Acute allergicDrug inducedHayfeverVernalAtopic
Allergen avoidance++++
Cool compresses++
Irrigation++
Levocabastine+
Lodoxamide+
Sodium Cromoglycate+++
Gutt. NSAIDS++/-
Gutt. Steroids+/-++