Set the lens with the higher absolute power on the focimeter support, neutralise or allow for any prescribed prism and then dot the reference point.
To measure this, mark the second lens at the ordered centration distance, place them back onto the focimeter with this mark centred and read the power
For vertical imbalance, any inaccuracy of less than 1mm between ordered lens positions or in distance between the two focimeter dots or that does not exceed 0.
3 gauge Ptychography Phasefocus Lens -- Profiler Confocal Optimec JCFD -- Low coherence Lumetrics OptiGauge -- interferometry MLS Beam profile Nightingale EOS -- reflectometry N-Gauge Power Focimeter
Topcon LM-8/8C 4.
Ask the patient if they have any other spectacles in addition to the pair about to be checked (eg, reading spectacles, sunglasses, a spare pair, or a newer pair they can't wear) and be sure to focimeter all of these.
For an optometrist to have an indication of the refractive error of a patient before they begin, in addition to the current spectacle focimeter result, and ahead of retinoscopy during the examination, gives considerable advantage of where and what direction the prescription may be going.
After developing this first instrument, the academic support officer went onto build, amongst other things, a progressive lens measurement machine that he patented, and a scanning focimeter
which second-year optometry students at Aston University use today.