Redness of the eye is one of the commonest signs in ophthalmology, being a feature of a wide range of ophthalmological conditions, some of which are severe and sight threatening, whereas others are mild and of little cons- equence. Occasionally, the red eye can be the first sign of important systemic disease. It is important that every practicing doctor has an understanding of the differential diagnosis of this common sign, and a categorisation of the signs, symptoms and management of the red eye will now be made from the standpoint of the nonspecialist general practitioner.
The simplest way of categorising these patients is in terms of their visual acuity. As a general rule, if the sight, as measured on the Snellen test chart, is impaired, then the cause might be more serious. The presence or absence of pain is also of significance, but as this depends in part on the pain threshold of the patient, it can be a misleading symptom.
Disease of the conjunctiva alone is not usually painful, whereas disease of the cornea or iris is generally painful.
The red eye will, therefore, be considered under three headings: the red eye that sees well and is not painful, the red painful eye that can see normally, and the red eye that does not see well and is acutely painful.
Red Eye That Is Not Painful and Sees Normally
Subconjunctival Haemorrhage
Careful examination of the eye will easily confirm that its redness is due to blood rather than dilated blood vessels, and the redness might be noticed by someone other than the patient. The condition is common and resolves in about 10–14 days. It is extremely unusual for a blood dyscrasia to present with subconjunc- tival haemorrhages. Although vomiting or a bleeding tendency can also be rare causes, the normal practice is to reassure the patient rather than embark on extensive investigations, because the majority of cases are caused by spontaneous bleeding from a conjunctival cap- illary. This might be spontaneous and can result from a sudden increase in venous pressure, for example after coughing.
Conjunctivitis
Examination of the eye reveals inflammation, that is, dilatation of the conjunctival capillaries and larger blood vessels, associated with more or less discharge from the eye. The exact site of
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The Red Eye
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the inflammation should be noted and it is esp- ecially useful to note whether the deeper capil- laries around the margin of the cornea are involved. The resulting pink flush encircling the cornea is called “ciliary injection” and is a warning of corneal or intraocular inflam- mation. For clinical purposes, it is useful to divide conjunctivitis into acute and chronic types.
Acute Conjunctivitis
This is usually infective and caused by a bac- terium; it is more common in young people. It can spread rapidly through families or schools without serious consequence other than a few days incapacity. When adults develop acute con- junctivitis, it is worth searching for a possible underlying cause, especially a blocked tear duct if the condition is unilateral. Sometimes an ingrowing lash might be the cause or occasion- ally a free-floating eyelash lodges in the lacrimal punctum. The important symptoms of acute conjunctivitis are redness, irritation and stick- ing together of the eyelids in the mornings.
Management entails finding the cause and using antibiotic drops if the symptoms are severe enough to warrant this. However, it must be remembered that the inadequate and intermit- tent use of antibiotic eye drops could simply encourage growth of resistant organisms.
Chronic Conjunctivitis
This is a common cause of the red eye and almost a daily problem in nonspecialised ophthalmic practice. If we consider that the conjunctiva is a mucous membrane that is exposed daily to the elements, it is perhaps not surprising that after many years it tends to become chronically inflamed and irritable. The frequency and nuisance value of the symptoms are reflected in the large across-the-counter sales of various eyewashes and solutions aimed at relieving “eye- strain” or “tired eyes”. The symptoms of chronic conjunctivitis are, therefore, redness and irrita- tion of the eyes, with a minimal degree of dis- charge and sticking of the lids. If there is an allergic background, itching might also be a main feature. The chronically inflamed conjunc- tiva accumulates minute particles of calcium salts within the mucous glands. These conjunc- tival concretions are shed from time to time,pro- ducing a feeling of grittiness. When confronted with such a patient, there are a number of key
symptoms to be elicited and these can be related to a checklist of causes mentioned below.
The key symptoms of chronic conjunctivitis are as follows:
• Environmental factors, especially eye drops, make-up or foreign bodies.
• Lids stick in mornings?
• Do the eyes itch?
• Emotional stress or psychiatric illness?
The following is a checklist of causes of chronic conjunctivitis:
• Eyelids: deformities, such as entropion or ectropion.
• Displaced eyelashes.
• Chronic blepharitis.
• Refractive error: a proportion of patients who have never worn glasses and need them or who are wearing incorrectly pre- scribed or out-of-date glasses present with the features of chronic conjunctivitis, the symptoms being relieved by the proper use of spectacles. The cause is not clear but possibly related to rubbing the eyes.
• Dry eye syndrome: the possibility of a defect in the secretion of tears or mucus can only be confirmed by more elaborate tests, but this should be suspected in patients with rheumatoid arthritis or sarcoidosis.
• Foreign body: contact lenses and mascara particles are the commonest foreign bodies to cause chronic conjunctivitis.
• Stress: often a period of stress seems to be closely related to the symptoms and perhaps eye rubbing is also the cause in these patients.
• Allergy: it is unusual to be able to incrim- inate a specific allergen for chronic con- junctivitis, unlike allergic blepharitis. On the other hand, hay fever and asthma could be the background cause.
• Infection: chronic conjunctivitis can begin as an acute infection, usually viral and usually following an upper respiratory tract infection.
• Drugs: the long-term use of adrenaline drops can cause dilatation of the conjunc- tival vessels and irritation in the eye. In 1974, it was shown that the beta-blocking drug practolol (since withdrawn from the market) could cause a severe dry eye
syndrome in rare instances. Since then there have been several reports of mild reactions to other available beta-blockers, although such reactions are difficult to distinguish from chronic conjunctivitis from other causes.
• Systemic causes: congestive cardiac failure, renal failure,Reiter’s disease,polycythaemia, gout, rosacea, as well as other causes of orbital venous congestion, such as orbital tumours, can all cause vascular congestion and irritation of the conjunctiva. Migraine can also be associated with redness of the eye on one side and chronic alcoholism is a cause of bilateral conjunctival congestion.
Episcleritis
Sometimes the eye becomes red because of inflammation of the connective tissue underly- ing the conjunctiva, that is, the episclera. The condition can be localised or diffuse. There is no discharge and the eye is uncomfortable,although not usually painful. The condition responds to sodium salicylate given systemically and to the administration of local steroids or nonsteroidal anti-inflammatory agents. The underlying cause is often never discovered, although there is a well-recognised link with the collagen and dermatological diseases, especially acne rosacea.
Episcleritis tends to recur and might persist for several weeks, producing a worrying cosmetic blemish in a young person (Figure 7.1).
Red Painful Eye That Can See Normally
Scleritis
Inflammation of the sclera is a less common cause of red eye. There is no discharge but the eye is painful. Vision is usually normal, unless the inflammation involves the posterior sclera.
It is most often seen in association with rheumatoid arthritis and other collagen dis- eases and sometimes can become severe and progressive to the extent of causing perforation of the globe (Figure 7.2). For this reason, steroids must be administered with extreme care. Treat- ment normally is with systemically adminis- tered nonsteroidal anti-inflammatory agents, for example flurbiprofen (Froben) tablets.
Red Painful Eye That Cannot See
It is worth emphasising again that the red painful eye with poor vision is likely to be a serious problem, often requiring urgent admis- sion to hospital or at least intensive outpatient treatment as a sight-saving measure. The fol- lowing are the principal causes.
Acute Glaucoma
The important feature here is that acute glau- coma occurs in long-sighted people and there is
Figure 7.2. Scleritis.
Figure 7.1. Episcleritis (with acknowledgement to Professor H. Dua).
usually a previous history of headaches and seeing haloes around lights in the evenings. The raised intraocular pressure damages the iris sphincter and for this reason, the pupil is semi- dilated. Oedema of the cornea causes the eye to lose its luster and gives the iris a hazy appear- ance (Figure 7.3). The eye is extremely tender and painful and the patient could be nauseated and vomiting. Immediate admission to hospital is essential, where the intraocular pressure is first controlled medically and then bilateral laser iridotomies or surgical peripheral iridec- tomies are performed to relieve pupil block.
Mydriatics should not be given to patients with suspected narrow-angle glaucoma without con- sultation with an ophthalmologist.
Acute Iritis
The eye is painful, especially when attempting to view near objects, but the pain is never so severe as to cause vomiting. The cornea remains bright and the pupil tends to go into spasm and is smaller than on the normal side (Figure 7.4).
Acute iritis is seen from time to time mainly in the 20–40-year age group, whereas acute glau- coma is extremely rare at these ages. Unless severe and bilateral, acute iritis is treated on an outpatient basis with local steroids and mydria- tic drops. Some expertise is needed in the use of the correct mydriatic, and systemic steroids should be avoided unless the sight is in jeop- ardy. Because the iris forms part of the uvea, acute iritis is the same as acute anterior uveitis.
In many cases, no systemic cause can be found but it is important to exclude the possibility of
sarcoidosis or ankylosing spondylitis. The condition lasts for about two weeks but tends to recur over a period of years. After two or three recurrences there is a high risk of the development of cataract, although this might form slowly.
Acute Keratitis
The characteristic features are sharp pain, often described as a foreign body in the eye, marked watering of the eye, photophobia and difficulty in opening the affected eye. The clinical picture is different from those of the above two cond- itions and the commonest causes are the herpes simplex virus or trauma. The possibility of a perforating injury must always be borne in mind. Sometimes children are reticent about any history of injury for fear of incriminating a friend, and sometimes a small perforating injury is surprisingly painless. The treatment of acute keratitis has already been discussed in Chapter 6 and the management of corneal injuries will be considered in Chapter 16.
Neovascular Glaucoma
The elderly patient who presents with a blind and painful eye and who might also be diabetic should be suspected of having neovascular glau- coma. Often, a fairly well-defined sequence of events enables the diagnosis to be inferred from the history, as in many cases secondary neo- vascular glaucoma arises following a central retinal vein occlusion. Following retinal vein occlusion, patients typically notice that the vision of one eye becomes blurred over several Figure 7.3. Acute angle-closure glaucoma.
Figure 7.4. Acute iritis. The pupil has been dilated with drops.
hours or days. Some elderly patients do not seek attention at this stage and some degree of spon- taneous recovery can seem to occur before the onset of secondary glaucoma. Fortunately, only a modest proportion of cases develops this severe complication, which usually occurs, sur- prisingly enough, after 100 days, hence the term “hundred-day glaucoma”. Once
the intraocular pressure rises, the eye tends to become painful and eventually degenerates in the absence of treatment, and sometimes even in spite of treatment. This form of secondary glaucoma remains as one of the few indications for surgical removal of the eye, if measures to control intraocular pressure are unsuccessful.
