Test the patient's visual acuity, each eye separately , covering one at a time. Snellen's chart is used by Ophthalmologists.
Visual acuity is recorded as a fraction.
The denominator indicates the distance at which a normal eye can read the line. A pocket screener is used at the bedside. Hold the pocket screener at a distance of 12-14 inches. At this distance the letters are equivalent to those on Snellen's chart.