Guide:How to measure your eyesight

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Measuring your eyesight can be done in several different ways. Remember eyesight fluctuates from day to day based on many factors, one measurement alone is not necessarily the most accurate indication of your vision. Before you order new correction, or decide to reduce, try to get enough measurements to have a good idea what your typical vision is. Since you are measuring yourself, you can take the time to get the best idea of what your most consistent vision trends are. You will gain the most complete understanding of your vision trends should you track all three measuring methods.

Centimeter measurements

Centimeter measurements are seeing your distance to blur with a tape measure held against a screen or book. 12 point font is recommended, you will see blur at the same distance regardless of font size, however it will be easier to distinguish the edge of blur with 12 pt font. Remember you are seeking the point where clarity is no longer sharp, not the edge of readability (though if you wish to notate this too in your records you certainly may).

You can see various tools to accomplish this here.

This test can be used to check both near and far points, the difference between which determines presbyopia.

Eye chart

A Snellen chart is good as it controls a lot of variables. If you stand at the same distance with the same given pair of glasses in similar, or same lighting and notice an improvement over time, then it's safe to say your eyesight is improving.

If you check your Snellen with your next, i.e. reduced pair of normalized, and you can see the 20/50 line, you could start using those, provided you are reasonably comfortable with that much blur. But always keep your previous correction for driving, make sure you are being safe and within legal guidelines, check your local vision requirements. [1] Also note: the 20/50 standard is outdated and not actually recommended any longer, so please be aware of that fact should you choose to follow this.

Other static eye charts are possible, as well as the dynamic Dyop chart.

Please note: The longer charts tend to be more accurate in determining your real world vision in a given correction. For further assurance of real world vision meeting expectations avoid using excess lighting and/or active focus during measurements.

Landmarks (real world objects)

This usually works best with signs. Take a given object, preferably with text that you see very frequently and see whether there's an improvement over time in how well you can see the object.

This one might not produce hard figures like the other two methods, so it's better to use this in conjunction with the other the measuring methods and never as an exclusive means of assessing your vision, as it can be far too objective and you can not control important variables like lighting.

However if you are looking to have a tangible point of reference for this also, try this: Quick Reference: Real World Acuity Guide

See Also

References

2. The EndMyopia Blog, https://courses.endmyopia.org/measure/?fbclid=IwAR01yIImN77PO3L1yU0LpTTxfW11uIRSFAbj9KoB53_2KxOP_hrZjoQYYDk

(with links that Include printable diopter ruler)