ABSTRACT
Examination of the eye involves assessment of the retina and optic nerve, visual acuity, visual fields, and colour vision.
Visual acuity (VA) measures the function of the eye and gives some idea of the patient’s disability. VA is tested with the Snellen chart and is usually expressed as a fraction: for example, if the last line on the chart that can be read accurately by a patient 6 m away is the line that a person with normal vision can read at 24 m then the patient has a VA of 6/24. Vision should be tested with the aid of the patient’s usual glasses or contact lenses. To achieve optimal VA, the patient should be asked to look through a pinhole. This reduces the effect of any refractive error and is particularly useful if the patient cannot use contact lenses because of a red eye or has not brought their glasses. You should state that VA should be formally tested with the Snellen chart at 6 m distance. However, in the examination situation, a quick assessment can be made by simply asking the patient to read words from a book.
