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See also: Guide:How to measure your eyesight

Stay calm

In general, your measurements actually change wildly within the day. They're mostly useful for checking that you're not going off track with habits changes, or for measuring relative changes in vision in different circumstances. (e.g. diet, time of day, and activity)

As far as what progress you can see, that appears to actually be fairly individual. You need to measure to learn about how you see things. But think of general changes on the span of multiple weeks, or even a month or so.

Measurements are a learning process, not a goal

Centimeter Measurement

The cm measurement uses a basic optics formula to calculate the diopters of correction you need to see clearly long distance.

  1. 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.
  2. Calculate diopters from the measurement: Diopters = -100cm/cm measurement.
  3. 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.
  4. If your result is stronger than -4, you'll likely have problems getting consistent readings since the margin for error is much smaller. For best results: please see: Guide:Measuring with differentials.

Trial Refraction

If your myopia is high and/or complex, you may need a trial lens kit to measure your own vision, or you may just stick to professional optometrist exams.


See Also


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