An Overview of the Ocular System

Excerpt

The examiner's ability to help a patient clarify or elaborate on an ocular symptom and the examiner's knowledge of the significance of some common ocular symptoms will often facilitate correct diagnosis on the basis of history alone.

When a patient complains of eye pain (Chapter 112), it is essential to describe the ocular discomfort clearly. The examiner must differentiate between itching, tearing, burning, foreign body sensation, photophobia, deep pain, pain on eye movement, or tenderness to touch. Frequently, the patient will have more than one type of symptom and the examiner must ask, "Which part of your eye problem is most disturbing to you?"

Itching of the lids and conjunctiva is a fairly specific symptom that may be associated with surface allergy, hay fever, or other forms of Type I immediate hypersensitivity. Burning is an external ocular symptom as occurs commonly in conjunctivitis. Foreign body sensation is more specific and occurs when there is a break in the corneal epithelium, exposing sensitive corneal nerves to the opening and closing of the eyelids (e.g., corneal abrasion).