CLINICAL REVIEW: Dealing With the Acute Red Eye

The essentials

* Serious causes may be excluded by thorough history and examination.

* Topical steroids in the eye are best avoided in general practice.

* A detailed history can help distinguish between episcleritis and scleritis.

* Patients with visual haloes may have acute angle closure glaucoma.

* Zoster of trigeminal nerve’s ophthalmic branch often involves the eye.

1. Fundamentals for assessing the red eye

The acute red eye is a common problem in children and adults and the initial consultation is usually with the GP, or sometimes at an A&E department or an optometrist.

The aetiology may be difficult to determine, and there is understandable apprehension among primary care professionals that they might be missing a serious ocular condition. However, a careful history and clinical examination will usually allow them to make the diagnosis.

Important features of the history include onset, redness, pain, photosensitivity, discharge and visual symptoms. Every effort should be made to record a visual acuity, with appropriate glasses correction, and a pinhole. A reduced three metre Snellen chart can be helpful.

Conjunctivitis

Conjunctivitis is usually characterised by rapid onset of a watery red eye, with soreness and a foreign body sensation. A purulent discharge may indicate bacterial conjunctivitis. Vision should be unaffected, unless there is a coexisting keratitis. The conjunctiva is often intensely hyperaemic, and there may be associated follicles, haemorrhages, and lymphadenopathy. Check the pre-auricular lymph nodes.

Viral conjunctivitis

In acute viral conjunctivitis (AVC), one eye is typically affected before the other. Involvement of the second eye may be milder. AVC runs a self-limiting course, antibiotics are unnecessary, and toxicity associated with their use can exacerbate the condition. Supportive treatment with lubricants such as hypromellose can help. Patients should be warned that they should come back if visual loss or any photophobia occur because a few patients may develop severe adenoviral keratitis.

Herpes simplex can cause a similar picture. Herpetic vesicles on the skin, and recent labial herpes may suggest the diagnosis, and viral swabs can confirm it.

Chlamydia conjunctivitis

Chlamydia conjunctivitis presents as a subacute mucopurulent conjunctivitis that often develops into a chronic conjunctivitis unresponsive to multiple courses of antibiotics. A marked follicular reaction in the inferior conjunctival fornix is seen in the chronic stage.

Diagnosis is often delayed and a high index of suspicion may be needed. The diagnosis is made by enzyme immunosorbent assay, cell culture, or polymerase chain reaction. Patients with a confirmed diagnosis of chlamydial conjunctivitis should be offered a genitourinary assessment, because 50 per cent of cases will have genitourinary chlamydia. Treatment consists of systemic tetracycline.

2. Blepharitis and keratitis

Blepharitis is an inflammation of the lid margin. Key features are lid crusting, redness of the margins, and misdirected lashes. It is frequently associated with a history of styes and conjunctivitis.

Species of staphylococci and other skin flora are the major causes. Chronic blepharitis is a common cause of contact lens intolerance, and there may be meibomian gland abnormalities.

The most effective treatment is lid hygiene, with daily scrubbing of the lid margins using cotton buds dipped in a weak solution of baby shampoo. Short courses of anti-staphylococcal treatment such as fucidic acid 1% drops can be helpful. Topical steroids are best avoided in general practice and are only rarely used even by ophthalmologists. Long-term oral tetracyclines help if there is associated meibomian gland disease in the presence of rosacea.

Infectious keratitis

Other corneal pathology, for example an infective keratitis, corneal abrasion, or foreign body, must be considered in the diagnosis of the acute red eye.

Characteristics of keratitis include profuse reflex lacrimation, pain, marked photophobia, with lid spasm, and reduced vision. A white lesion – an ulcer – may be visible on the cornea, either visible with the naked eye, or on microscopic slit lamp examination.

Fluorescein staining will assist in showing the extent of the ulcer: it can be very helpful if this reveals the characteristic ‘dendritic’ shape of a herpes simplex ulcer. Corneal sensation can be tested with a wisp of sterile tissue. The sensitivity of the cornea may be reduced in neurotrophic cornea occurring secondary to herpes zoster or herpes simplex.

An infectious corneal ulcer may occur secondary to lid and conjunctival inflammation, and is often due to trauma or contact lens wear. Common causes of corneal ulcers are bacterial infections, usually with Staphylococcus sp, Pseudomonas and Streptococcus pneumoniae, or viral infections, most commonly herpes simplex and zoster.

Marginal keratitis

Marginal keratitis is common, and thought to be caused by a hypersensitivity to staphylococcal exotoxins. It typically presents as a sub-epithelial infiltrate in the peripheralcornea, with a localised dilatation of the limbal superficial vessels. The epithelium may ulcerate. This can be identified with fluorescein. Treatment is with antibiotics, with a short course of topical steroids.

Subconjunctival haemorrhage

Subconjunctival haemorrhage is not an infectious condition and presents as the sudden onset of a red patch under the conjunctiva, with mild tenderness and discomfort. It may arise spontaneously, following slight trauma, or as a result of local congestion due to coughing or sneezing.

The haemorrhage resolves spontaneously over two or three weeks. Recurrent or bilateral episodes suggest hypertension or blood dyscrasias. In the presence of head trauma, extensive Subconjunctival haemorrhage raises the possibility of the passage of blood from a fractured base of skull that has travelled through the floor of the orbit into the Subconjunctival space.

3. Episcleritis and scleritis

Episcleritis is an inflammatory condition affecting the eye. It is self-limiting, and only rarely associated with systemic connective tissue disease. There is usually a localised area of episcleral injection, or less commonly a nodule on the epsiclera. Eye tenderness and mild soreness and burning are typical, but pain should not be severe. It can be differentiated from conjunctivitis by the absence of lid swelling, discharge or follicles. The vision is unaffected.

Patients are typically young adults, and may have had previous episodes. Although it is self-limiting, the duration of symptoms can be shortened with topical steroids (under an ophthalmic specialist’s supervision) or with oral NSAIDs. Systemic investigations are usually unnecessary, but frequent attacks suggest connective tissue disease (mainly systemic lupus erythematosus).

Scleritis

It is important to distinguish episcleritis from scleritis, and a careful history must be taken in all patients. The history is crucial because the nature of the pain differs from episcleritis in the form of a severe, unremitting ache that disturbs sleep and may be worse with ocular movements.

Macroscopically it can be difficult even for experts to distinguish scleritis from episcleritis. Anterior scleritis is commonest and may be diffuse or nodular. It may also occur bilaterally. In about 5 per cent of cases, the scleritis is associated with necrosis. Necrotising scleritis is commonly associated with rheumatoid arthritis and is characterised by a blueish discoloration of the sciera.

The discoloration of the sciera indicates scierai thinning, and carries a worse prognosis, because in extreme cases the thinning can lead to perforation.

Relevant investigations should be directed to discovering associated systemic diseases. In order of frequency these are rheumatoid arthritis, the vasculitides (Wegener’s granuloma,polyarteritis) and relapsing polychondritis.

Posterior scleritis

An uncommon form of scleritis is posterior scleritis, with inflammation of the posterior coats of the eye without anterior inflammation. The eye appears white. Most patients present with the typical pain. Visual symptoms may be present as a consequence ol retinal serous detachment or disc swelling.

The diagnosis is confirmed by demonstrating thickening of the posterior sciera on ultrasound B scan testing. This form of ultrasound uses the amplitude of each returning signal to differentiate the layers within the eye, and will demonstrate abnormal scierai thickening in scleritis.

4. Anterior uveitis and acute glaucoma

Anterior uveftis

Acute anterior uveitis is characterised by acute symptoms of pain, photophobia, and decreased vision. Macroscopically the degree of redness is most intense at the limbus, distinguishing it from conjunctivitis. Deposits on the corneal endothelium (keratic precipitates) may be seen, and miosis of the iris, adhesions between the lens and iris, and hypopyon may all be present.

Slit lamp microscopy will show cells in the anterior chamber. Vision will be reduced commensurate with the degree of inflammation. Fundoscopy will exclude posterior uveitis.

Ask the patient about systemic symptoms that may suggest ankylosing spondylitis, inflammatory bowel disease, sarcoidosis and psoriasis. Investigations are not helpful if there are no systemic symptoms. I\n these cases the single most useful test is HLA B-27 screening. The positive haplotype occurs in about 8 per cent of Caucasians, and represents a 10-times risk for anterior uveitis.

Acute angle closure glaucoma

Acute angle closure glaucoma occurs in eyes that are predisposed to the condition. The peak ages for it to occur are between 50-55, and over 70. It is more common in females. Any patients who present complaining of visual haloes must be taken seriously, and should be referred promptly for an ophthalmic examination and intra-ocular pressure measurement.

Primary angle closure glaucoma

The commonest form of acute glaucoma is primary angle closure glaucoma (PACG). A number of factors predispose eyes to PACG, including a short axial length, a shallow anterior chamber, lens enlargement, and a steep cornea. Patients are usually hypermetropic, and this can quickly be confirmed by examining the glasses, which will magnify.

The mechanism of PACG

In PACG the passage of aqueous is blocked by an iris-lens touch (also called pupil block). This leads to an appositional block between the peripheral iris and the drainage angle.

An acute attack usually consists of a rapid onset of redness, severe pain, haloes, blurring of vision, nausea and vomiting. Characteristic signs include eye redness, corneal oedema (a lustreless’ cornea), a shallow anterior chamber, and a fixed unreactive oval-shaped pupil. The eye will feel rock hard on digital palpation, and tonometry will show a markedly elevated intra-ocular pressure, usually in the range of40-60mmHg.

A subset of patients have sub-acute attacks of angle closure, with less dramatic symptoms including intermittent eye redness, headaches, nausea, and haloes, particularly in twilight.

5. Herpes zoster ophthalmicus

Herpes zoster ophthalmicus (HZO) occurs when zoster affects the ophthalmic division of the trigeminal nerve.

The eye may become involved when the disease affects the maxillary division of the trigeminal nerve, but this is rare. Lid and forehead signs include the typical sequence of zoster pustules, papules and vesicles that eventually crust over, although necrosis may occur.

Many structures involved

The eye is affected in 50 per cent of cases, and many ocular structures can be involved. Conjunctivitis and episcleritis are common, and are associated with vesicles at the lid margin.

Unless severe necrosis occurs, they usually do not require treatment. Superficial keratitis usually occurs within days, and is characterised by epithelial defects and dendriform lesions. These can be identified with fluorescein staining.

Less commonly, deeper stromal involvement occurs, with nummular and disciform keratitis in the second and third weeks. Anterior uveitis is a common complication and usually occurs two or three weeks after the onset of the rash. Rarer ocular complications include scleritis, optic neuritis, cranial nerve palsies, and acute retinal necrosis. HZO should be treated with systemic high-dose antivirals such as acyclovir or a suitable analogue. Topical acyclovir is of no value in the treatment of ocular disease.

Other complications

Complications such as disciform keratitis and uveitis respond well to topical steroids. These usually have to be slowly tapered off over a period of many months, not only because of adrenal suppression, but to minimise the risk of rebound inflammation once the steroids have been stopped.

The possibility of HIV should be considered in any patients with HZO who are under the age of 45 and who belong to a high-risk group. Patients with AIDS tend to have more severe attacks.

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Viral conjunctivitis runs a self-limiting course; antibiotics may exacerbate rather than help the condition

Key points

* The acute red eye is a common problem in children and adults, with the initial consultation often with a GP.

* Antibiotics may exacerbate viral conjunctivitis.

* Patients who have chlamydia conjunctivitis should have a genitourinary assessment.

Fluorescein staining may reveal a dendritic ulcer

Key points

* Blepharitis is an inflammation of the lid margin with lid crusting and redness of the margins.

* Infective keratitis, corneal abrasion and foreign body can all cause an acute red eye.

* Marginal keratitis is thought to be caused by hypersensitivity to staphylococcal exotoxins.

* Subconjunctival haemorrhage presents with sudden onset of a red patch under the conjunctiva with mild tenderness and discomfort.

Episcleritis is self-limiting and any pain is mild

Scleritis; painful, and thinning may cause perforation

Key points

* Episcleritis is an inflammatory condition and is self- limiting.

* Differentiation from conjunctivitis is by the absence of lid swelling and discharge.

* In extreme cases of scleritis, the scierai thinning can lead to perforation.

* Between 20-40 per cent of scleritis patients will have an associated connective tissue disease.

A hypopyon may be present in anterior uveitis

Key points

* Acute anterior uveitis is characterised by acute symptoms of pain, photophobia, and decreased vision.

* The peak ages for acute angle closure glaucoma are between 50 and 55 years, and over 70 years.

* A subset of patients have sub-acute attacks of angle closure.

Zoster of the trigeminal nerve may involve the eye

Key points

* Many ocularstructures can be involved in HZO.

* Anterior uveitis is a common complication, and occurs two or three weeks afterthe rash.

* Topical acyclovir is of no value in the treatment of ocular disease.

* HIV should be considered in any patients with HZO who are under 45.

Further resources

Further reading

ABC of Eyes by P Shah, published by BMJ Books.

Websites

See Medicine on the Web, page 42

Previously in Clinical Review

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Contributed by Mr Mark Westcott, consultant ophthalmic surgeon at St Bartholomew’s and the Royal London Hospitals, and at Moorfields Eye Hospital and The London Clinic

Copyright Haymarket Business Publications Ltd. Mar 25, 2005