Snellen vs Diopter Measurements: Which is more accurate?

The title says it all. I can see the big ‘E’ on the Snellen chart without, which is about 20/200 and that roughly translates to -1.50. But I noticed when I measure my diopters through the distance to blur method (Jake’s inverse meters method), I get a much higher diopter number-- usually around -2.25. Thus my question: which is a more accurate measurement of your true eyesight? Snellen chart or distance to blur?

If Jake has written about this topic then please leave a link!

For me both is confusing. I stopped measuring. I just care about the progress, that I can use lower glasses after 3-4 months and that I can clear up with them the same blurry text like with the older glasses 3-4 months before. Now Im waiting for EyeQue VisionCheck to get some confirmation. I think confirmation is important, because through the long journey you “stop believing how good you can see”.

I think the cm method is the real deal, because it is about clarity. The Snellen is about readability. But readability means still there could be some blur and that blur is what you do not measure and what it makes more inaccurate.

This is the first I’ve heard of that. Have others in EM used it? Has Jake spoken about it?

A few others on the forum have talked about that device:

Cm measurement is for measuring close up vision.
Snellen is to measure mid-distance vision (3 to 6 metres)
Street signs, shop signs, licence plates, etc are to measure real distance vision.

What many people don’t realise is that you can have different visual acuity at different distances. During EM you will have to retrain your eyes to switch between distances, too.
Also as pointed out: seeing the first sign of blur close up and just being able to “read” a known letter are not the same.


Sounds terrible! Why would you pay for this, Tony87?

This seems to me one of the most sensible things I’ve read lately!

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Well I ordered the newer version called “VisionCheck” for 74€ total. I want to have a confirmation device, even if it would overprescribe, I want to see a confirmation about the trend.