Lensmeter
![One of five comprehensive instructional videos derived from the original Flash animation on the use of the Topcon lensmeter (vertometer). Produced by Dr Suzane Vassallo with La Trobe University. These videos are also available Wikiversity, Youtube and Archive.org.](/Images/godic/202501/23/-Vertometry-InstrumentSetUp-Calibration.ogv5112.jpg")
![A Lensmeter in an Optical shop](/Images/godic/202501/23/Lensmeter5112.jpg")
![A simple lensmeter cross sectional view.
1 – Adjustable eyepiece 2 – Reticle 3 – Objective lens 4 – Keplerian telescope 5 – Lens holder 6 – Unknown lens 7 – Standard lens 8 – Illuminated target 9 – Light source 10 – Collimator 11 – Angle adjustment lever 12 – Power drum (+20 and -20 Diopters) 13 – Prism scale knob](/Images/godic/202501/23/Lensmeter-25112.png")
A lensmeter or lensometer, also known as a focimeter or vertometer, is an ophthalmic instrument. It is mainly used by optometrists and opticians to verify the correct prescription in a pair of eyeglasses, to properly orient and mark uncut lenses, and to confirm the correct mounting of lenses in spectacle frames. Lensmeters can also verify the power of contact lenses, if a special lens support is used.