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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.


A red eye accounts for at least 80% of 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 40.1.

Table 40.1The red and tender eye: diagnostic strategy model

Key facts and checkpoints

  • Acute conjunctivitis accounts for over 25% of all eye complaints seen in general practice.2

  • Viral conjunctivitis (compared to bacterial) is more common in adults, is usually bilateral and discharge is more watery than purulent.3

  • 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, protozoal infection or inflammatory disorder such as ankylosing spondylitis.5

  • Herpes simplex keratitis (dendritic ulcer) often presents painlessly, as the neurotrophic effect grossly diminishes sensation.


The five essentials of the history are:

  • history of trauma (including wood/metalwork—foreign body)

  • vision

  • the degree and type of discomfort

  • presence of discharge

  • presence of photophobia

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.

When examining the unilateral red eye, keep the following diagnoses in mind:

  • trauma

  • foreign body, including intra-ocular (IOFB)

  • corneal ulcer

  • iritis (uveitis)

  • viral conjunctivitis (commonest type)

  • acute glaucoma

The manner of onset of the irritation often gives ...

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