Difference between revisions of Measurement
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Dlskidmore (talk | contribs) m (copied over from getting started) |
Dlskidmore (talk | contribs) m (→cm Measurement: make everything into steps!) |
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== cm Measurement == | == cm Measurement == | ||
The cm measurement uses a basic optics formula to calculate the diopters of correction you need to 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. This is your "cm measurement". | |||
[[Diopters]] = -100cm/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. | |||
# If your result is stronger than -4D, and you wear glasses, you'll need to correct for [[vertex distance]] to convert this from contacts diopters to glasses diopters. | |||
# If your result is stronger than -10, you'll likely have problems getting consistent readings. | |||
== Trial Refraction == | == Trial Refraction == |