Differential diagnosis of the acute red eye

The importance of this is in the management of minor ocular complaints, and the recognition of conditions requiring expert attention. Possible causes of the acute red eye can be divided into:

conjunctivitis;

keratitis;

uveitis;

episcleritis and scleritis;

acute glaucoma.

Conjunctivitis

Symptoms are grittiness, redness and discharge. Causes are infective, viral, traumatic or allergic. In the newborn it can be serious, and gonococcal and chlamydial infection must be excluded. Vernal conjunctivitis (Fig. 36.25) is a form of allergic conjunctivitis, usually worse in the spring and early summer, and often associated with other allergic problems such as hay fever. Clinically, most signs are under the upper lid which may have a cobblestone appearance instead of a smooth surface. Giant pupillary conjunctivitis with large papilli under the upper lid may be seen in soft contact lens wearers. This is usually due to an allergy to the sterilising solutions and may be helped by either using a preservative-free solution or using daily wear disposable lenses where these are applicable. Viral conjunctivitis has become much more common. Chlamydial and adenovirus infections must be considered. Adenoviral infections usually affect one eye much more than the other and are often associated with a palpable preauricular gland. Kaposi’s sarcoma can present like a subconjunctival haemorrhage (Fig. 36.26).

Considerable conjunctival irritation can be caused by the lids turning in (entropion) (Fig. 36.27) or turning out (ectropion) (Fig 36.28 and Fig 36.29) and by ingrowing lashes. The lids should be repaired surgically to their normal position.

Vision is not affected in conjunctivitis, but with some virus infections a keratitis may be present, and result in visual loss and pain. All of the other conditions are painful, and usually affect vision. Herpes simplex infection is the most serious, and presents itself as a dendritic (branching) ulcer, shown easily by stain­ing with fluorescein or Bengal rose. It is treated with acyclovir ointment five times a day. The use of steroid drops must be avoided as this can make the condition much worse (Fig. 34.30).

Cornea) ulceration may occur due to ingrowing lashes or corneal foreign bodies, marginal ulceration and infected ulcers. Infected ulcers can occur in patients wearing soft contact lenses. Herpes zoster (shingles) affects the ophthalmic division of the fifth nerve, and can give rise to a keratitis and uveitis. It is important to exclude the use of steroid drops until a diagnosis has been made. Local anaesthetic drops should also not be given on a regular basis.

Uveitis

This can be anterior (inns) or posterior. In anterior uveitis the pupil will be small, sometimes irregular, there is csrcum­cornea) injection and there may be keratic precipitates (KPs) present on the posterior surface of the cornea. Pain, photo­phobia and some visual loss are usually present. Posterior uveitis can present with a white eye and blurred vision. It usually takes a chronic course. Granulomatous diseases, Behçet’s disease, toxoplasmosis and cytomegalovirus infection should be excluded. Systemic steroids and cytotoxic drugs are sometimes useful in treating these conditions.

Episcleritis and scleritis

Episcleritis or inflammation of the episcleral tissue often occurs as an allergic reaction following an eye infection (Fig. 36.31).

Scleritis is a more serious condition in which the deeper sclera is involved. There is often an associated uveitis and thinning of the sclera. It may require the use of systemic steroids in order to treat adequately

Scleritis is often associated with severe rheumatoid conditions.

Acute glaucoma

This usually occurs in older, often hypermetropic patients. The cornea becomes hazy, the pupil oval and dilated, the vision very poor and the eye feels rock hard. In severe cases the pain may be accompanied by vomiting, and the pain can be mistaken for one of an acute abdomen. In doubtful cases the use of the tonometer to measure the intraocular pressure is a useful diagnostic procedure. Urgent treatment to reduce the pressure by pilocarpine, acetazolamide and mannitol should be started followed by a surgical iridectomy or laser iridotomy. The condition is usually bilateral, and the second eye usually needs treatment at the same time.

Except for a simple conjunctivitis, which is self-limiting, these conditions require expert treatment and a specialist opinion should be sought.

A painful eye with a third nerve palsy often signifies an intracranial aneurysm and should be investigated immediately.