![](https://coimages.sciencemuseumgroup.org.uk/62/70/medium_thumbnail_2000_0086.jpg)
![Test-types with rear illumination, for testing visual acuity](https://coimages.sciencemuseumgroup.org.uk/2/123/medium_a627002.jpg)
Test-types with rear illumination, for testing visual acuity, English, probably c.1950
Back lit for a clearer view, this display is a chart of letters used by an optician to test a person’s sight at various distances. Such charts are perhaps the most iconic objects in sight testing. A patient with good vision should be able to read the letters at a distance of six metres. The original sight charts were developed in the 1850s by Dutch ophthalmologist Hermann Snellen (1834-1908). The letters, from largest to smallest, are all a precise shape and size. Such charts are still commonly used.
Details
- Category:
- Ophthalmology
- Collection:
- Sir Henry Wellcome's Museum Collection
- Object Number:
- A627002
- type:
- snellen test types