Snellen's test type, United Kingdom, 1901-1930
Located at the back of this display is a chart of letters used to test a person’s sight at various distances. With good vision, the patient should be able to read the letters at a distance of six metres. The chart was developed in the 1850s by Hermann Snellen (1834-1908), a Dutch ophthalmologist, and is still used today. The letters, from largest to smallest, are all a precise shape and size. The board is shown here in a display of sight testing in the 1930s.
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Glossary: Snellen test types
Chart used for vision testing. The chart shows lines of black letters varying in size from large to small down the chart. Which a patient is asked to read. The optician is able to tell the level of the patient's eyesight when s/he can not read any further.