Refraction Certificate Focimetry
Focimetry and hand neutralisation are how you read an existing spectacle prescription, and they feature directly in the Refraction Certificate. The instrument work needs practice, but the optics behind it is straightforward once drilled. This guide covers what to master and how to prepare.
Last updated 21 July 2026
What the focimetry station involves
You measure a spectacle prescription with a non-automated focimeter, or neutralise it by hand as an alternative, and record sphere, cylinder and axis clearly. Prisms, including vertical and Fresnel prisms, and the near add can also feature, so you need to identify and quantify them accurately.
The optics to be fluent in
Be comfortable with prescription notation and transposition, identifying cylinder axis and power, reading prism power and base direction, and separating the distance prescription from the near add. These are precisely the conversions a question bank can make automatic before you are at the instrument.
How to prepare for the focimetry station
Practise on a real focimeter and rehearse hand neutralisation with supervision so the mechanics are reliable. In parallel, drill notation, transposition and prism questions with worked explanations, so the recording and the maths never cost you marks under time pressure.
Focimetry FAQ
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