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142 bytes added ,  00:18, 6 September 2020
→‎cm Measurement: make everything into steps!
== cm Measurement ==
A simple test for your level The cm measurement uses a basic optics formula to calculate the diopters of myopia is correction you need to hold see clearly long distance. # Hold a ruler up to your eye, and measure how far away you can still read text without [[blur]]in centimeters. If you measure this distance in centimetres, this This is your "cm measurement". #* The ideal precise measurement is from the surface of your eyeball, but this is obviously not safe, so measure from some facial structure near your eye. #* Consistency is more important than accuracy, you want to be able to track your small changes over the course of a day, and larger changes over time. # Calculate diopters from the measurement: [[Diopters]] = -100cm/cm measurement. This test # If your result is fairly accurate up stronger than -4D, and you wear glasses, you'll need to about -10 Diopters. This is not corrected correct for [[vertex distance]], but below to convert this from contacts diopters to glasses diopters.# If your result is stronger than -4D vertex distance has no significant effect10, and your [[normalized]] lenses should be a little low anywayyou'll likely have problems getting consistent readings.
== Trial Refraction ==

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