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diopsimeter

American  
[dahy-uhp-sim-i-ter] / ˌdaɪ əpˈsɪm ɪ tər /

noun

Ophthalmology.
  1. an instrument for measuring the field of vision.


Etymology

Origin of diopsimeter

di- 3 + Greek ops- (stem of ópsis ) sight, vision + -i- + -meter