Cornea

The most common injury to the cornea is from the corneal foreign body and this has already been described in Chapter 5. Almost as common is the corneal abrasion. It is odd how this is so often caused by the edge of a newspaper, a comb or a child's fingernail. Abrasions from the leaves of plants or twigs need special attention because of the type of infection that can occur (fungal), but any abrasion can lead to the condition known as recurrent abrasion. Here, the patient experiences a sharp pain in the eye in the early morning usually on waking, sometimes many months after the initial injury. It is thought that the lid margin adheres to the area of weakened healed corneal epithelium during sleep. The diagnosis is easily missed if the patient has forgotten about the original injury and if the cornea is not examined carefully with the slit-lamp biomicroscope. This problem of recurrence is a reason to treat these abrasions with some care and to provide the patient with a lubricating ointment to be used at night for some time after the original injury has healed. Sometimes, recurrent abrasion results from a rare inherited disorder of the corneal epithelium.

When a patient presents with a corneal abrasion, the eyelids are often swollen perhaps from rubbing and the distress and agitation can be considerable. Examination may be impossible without first instilling a drop of local anaesthetic. These drops should never be continued as treatment because they could seriously delay the healing of the cornea.

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