Optometer, inventor (type), Badal, European, 19th century
Optometrists are trained to examine eyes and prescribe visual aids such as spectacles. This optometer dates from the 1800s. The optometer was used with various lenses to determine the refraction of the eye. Refraction means the extent to which light is bent by an individual’s eye. The result can determine how short sighted or long sighted they are, and the strength of spectacles required.
In the second half of the 1800s, ophthalmologists also devised instruments to measure the separate components of vision. Dr Jules Badal developed this instrument in 1876. It was based on an optometer invented by William Porterfield in 1759.