# Difference between revisions of Measurement

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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 == |

## Revision as of 00:18, 6 September 2020

## 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".
- 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

If your vision is worse than -10D, you may need a trial lens kit to measure your own myopia, or you may just stick to professional optometrist exams.

## Tools

- EndMyopia Diopter Calculator
- Varakari's Vision Log Tool
- EndMyopia cm calculator
- Measurement
- The iOS Sight Meter App
- The Android Diopter Calculator