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Those with sore eyes … find the light painful, while the darkness, which permits them to see nothing, is restful and agreeable.
DIO CHRYSOSTOM (40–115 CE)
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A red eye accounts for at least 80% of patients with eye problems encountered in general practice.1 An accurate history combined with a thorough examination will permit the diagnosis to be made in most cases without recourse to specialist ophthalmic equipment. A summary of the diagnostic strategy model is presented in TABLE 51.1.
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Key facts and checkpoints
Acute conjunctivitis accounts for over 25% of all eye complaints seen in general practice.2
A purulent discharge indicates bacterial conjunctivitis.3
A clear or mucous discharge indicates viral or allergic conjunctivitis.
Viral conjunctivitis can be slow to resolve and may last for weeks.
Pain and visual loss suggest a serious condition such as glaucoma, uveitis (including acute iritis) or corneal ulceration.
Beware of the unilateral red eye—think beyond bacterial or allergic conjunctivitis. It is rarely conjunctivitis and may be a corneal ulcer, keratitis, foreign body, trauma, uveitis or acute glaucoma.4
Keratitis (inflammation of the cornea) is one of the most common causes of an uncomfortable red eye. Apart from the well-known viral causes (herpes simplex, herpes zoster, adenovirus and measles), it can be caused by fungal infection (usually on a damaged cornea), bacterial infection or inflammatory disorder such as ankylosing spondylitis.5
Herpes simplex keratitis (dendritic ulcer) often presents painlessly as the neurotrophic effect grossly diminishes sensation.
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The five essentials of the history are:
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history of trauma, especially as indicator of intraocular foreign body (IOFB)
vision
the degree and type of discomfort
presence of discharge
presence of photophobia
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The social and occupational history is also very important. This includes a history of exposure to a ‘red eye’ at school, work or home; incidents at work such as injury, welding, foreign bodies or chemicals; and genitourinary symptoms.
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When examining the unilateral red eye keep the following diagnoses in mind:
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The manner of onset of the irritation often gives an indication of ...