Picking normalized after years of undercorrection - is it ok to have reduced lenses?


I spent the last 20 years undercorrected wearing differentials on a regular basis. Very much used to living in a blur. My pattern recognition is superb! I really don’t mind.

Trying to decide what would be a good normalized measurement for me. How far do I actually need to see in normalized for the EM to be effective?

  • Far away car license plates when driving?
  • Street signs far away?
  • Or something that I am just comfortable with?

I can practice AF at any distance, so if I wear somewhat reduced normalized, I can just practice it at the edge of my blur, right? Even if its closer than it would be with full normalized lenses.

Also, I already have a range of glasses (or as I used to say, a range of crutches, based on an activity). I have glasses for driving, for shopping, for a time around the house, etc. I am ok switching between them based on the activity I do. Though I actually rarely did, as I just stuck to my differentials for most things. I even have two pairs of differentials, for reading and for computer work. I am pretty neurotic…

Aside from the hassle and nuttiness of switching glasses based on the activity I do and the distance required (which I don’t mind at all), is there any problem with having multiple planes of vision that I have created this way? It feels very overprescribed to use my driving glasses at home…

Does it really matter how strong my normalized are, as long as I don’t use them for close work and practice AF?

Please advise. Thank you!

I’d probably go for very close to full correction with the idea that you want to set a new baseline for yourself of almost (but not quite) no blur, and you’ll try to active focus that tiny remaining blur away to no blur. -9.5 or -9.25 (if you can clear it up all the way.)

For differentials you want the minimum amount of correction that lets you do your activity without blur (just able to see your desk or your screen).

[If they were my eyes I’d add base-in prism to help relieve eyestrain at the computer (convergence and accommodation are the things that make sustained near work hard on your eyes, lowering diopters gets rid of accommodation, adding base-in prism reduces convergence.) That’s not really a standard EM practice, but it’s a known “thing” that can be helpful.]

For normalized you want the maximum amount that’s just shy of full correction. You’re trying to retrain your brain to be picky about small amounts of blur and say “not good enough” and make tiny focus adjustments.

I like silly analogies. Think of blur like being a small puddle of water on the floor. If you’re used to swimming in deep water all the time you don’t really care if the water is is 10 feet deep or 100 feet deep. If you’re expecting the floor to be perfectly dry, and you see a tiny puddle there, you’ll say “hey, this floor is wet” and mop it up.

The other thing that always seems to help is more outdoor time. Get outdoors as much as you can. @Alexbreedon1111 is coming down from high myopia I think, so is @Candacew.wong – they can probably give you more first-hand insight into high myopia EM journey because they’ve been making it work for them.

Also, if you haven’t already, put up an eye chart and see what the different strengths do for you in terms of being able to read the various lines on the chart in various lighting conditions. You might find you can see better than 20/20 in good light with greatly reduced correction, but need close to full correction at night. The more you can make it easy for you to measure things, the more guesswork it takes out of the whole process.


This can be a start. A good start.
Basically you have uncorrected vision and fully corrected vision. Those are what they are. Those are “absolute” ends of the range of corrections.
Between these 2, it is more or less your choice to select other distances - but for the sake of simplicity EM suggests adding only 1 in-between distance, and that’s the differentials. But as you say, the trick is simply to choose the right glasses for the right distance. Works best with a typical distance that you spend most of your time with. (For most people that is the monitor for work / school)
Some people go for 2 in-between distances: e.g. monitor and books / monitor and at home (which is typically max 6 meters), monitor and a hobby like embroidery, etc.

However, there are a lot of “just throw your glasses away” methods which promote introducing a lot of blur and then wait and see the blur magically clearing up… As you mention, after a while you will learn pattern recognition and compensate a lot from there and classify “quite blurry vision” as enough for every day life (I did it for many years, happily teaching classes and recognising students without actually being able to see their faces).

What is unique with EM’s approach is that EM promotes wearing corrections that give you vision close to 20/20 or 20/30, so when you wear less corrections your mind will still want to bring the vision back to that level of clarity. If you are very much used to blur this may feel like “too much” clarity first, so you may have to take this in steps.
The legal limit for driving in most countries is 20/40 vision which is -0.75D. This vision allows you to read number plates up to 20m or about 5 parking cars in a line, it allows you to be able to read the street and shop signs on the opposite side of the road, it allows you to walk into a café and read the menu above the counter, it allows you to read the departure times from the big display at the airport or at the train station. It is not 20/20, not full clarity, but it is a level of clarity that is highly recommended for the improvement, to set as a baseline.

Using this Snellen worked best for me:
There are instructions on the second page how to print it.

Check what you can see with good clarity with the different glasses you have at hand (not perfect vision but good clarity = no waiting time, no mixing up of F with P, C with O).
Lights, tiredness, stress, etc all affect your ability to focus

Depending on which line you can manage with good clarity these are the diopters to consider for “additional needed for full clarity”
20/200 = -2.00 to -2.50
20/100 = -1.5 to -2.00 (sometimes marked as -1.75 to -2.00)
20/70 = -1.25
20/50 = -1.00 to -1.25
20/40 = -0.75
20/30 = -0.5
20/25 = -0.25
20/20 = plano to -0.25
20/15 = plano (slightly overcorrected)
20/10 = plano (overcorrected)


Hello, I have a similar “situation” with @sophie_p where I am only using my old glasses as differentials for computer use and for mostly everything else, I don’t really wear glasses.

I use my Snellen eye chart and look at the 20/20 line and move until I get a little blur and it’s around 39 for each eye, which is around -2.5D. Sometimes I struggle with differentiating a little bit of blur and clarity so is that from blur adaptation (Still a bit new here, sorry)? Maybe I’ll just get new normalized and differentials? Advice please? Thanks for anything!

Use a 20ft Snellan for a reference point to help you figure out the right Rx for normalized and a reference on when to reduce normalized. Once you achieve 20/40 or 20/30 indoors on the 20ft Snellan than make a 0.25 reduction.

You want to stick to 2 pairs of glasses than one for close-up and one for distance. More than 2 is unnecessary and adds to the focal plane confusion.

And yes spend more time outdoors in sunlight looking at a distance. It will help you to accelerate your progress.


Another way to differentiate between blur and clarity is to think fuzzy. Are the letters getting fuzzy looking?

I find that straight lined letters are easier to distinguish and AF between clarity and fuzzy. So like the E or T versus an O or a B and black lettering on a white background is easiest to AF. I also find that white on a green background works well too. But you want to stick to the same reference before and after changing your normalized lenses.


This is how the method is structured and it is a method that works, I would advise you to do it according to the tried and true method that gets results.

@sophie_p This was well stated so I will just double down there:


Thank you and @Candacew.wong! I will use my last 7 measurements and maybe find the average centimeters so I can calculate my diopters and finally get proper differentials and normalized.

Love this :arrow_heading_up: Very handy. Thank you!!

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So your full opto correction is around -2.5D? If so, your differentials should not be stronger than -1D (assuming you have around 65 cms to the screen)

When picking earlier pairs of glasses for differentials, you have to make sure that they are fit for EM purpose: Fit means the gap between right and left eye, the strength of cyl, the axis, etc. If these are changing between full correction - normalised - differentials then your brain will be overloaded and confused.

Glasses online are very cheap. I’d prefer being on the safe side by getting a fresh opto measurement and then reduce from that for differentials and for the norms

The idea would be to get a pair of normalised glasses that enable you to read lines between 20/20 and 20/30 most of the time, and maybe 20/40 only when you are very tired and the lights are dim. Don’t worry about differentiating a little blur or not. The question is: can you differentiate F from P and O from C immediately and up to which line? That should be your guide on finding enough correction for normalised by aiming for better than 20/30.

I’d definitely recommend wearing normalised glasses for distance vision time: when you are outdoors and looking at people and objects and signs at least 5m away but obviously aiming for much bigger distances on average. This will teach the brain what clarity is the “desired level of clarity”, so your brain will want to clear vision to that level.


-2.5D is what I got based off of cm measurements on a printed page, but it isn’t a 12 pt font. Does that mean I should start over measuring by using a smaller font or the word “FOCUS” on the diopter calculator page?

I currently don’t have a proper normalized meaning that I’m just using my most recent under corrected glasses and same for differentials, but they are older than my normalized glasses meaning it’s more under corrected. Just to confirm, when I finally calculate my diopters, I will get my first pair of proper differentials and wear them for 4-6 weeks for closeup and use “fully corrected” glasses for other daily tasks. After around 4-6 weeks and enough AF, I will then get my first normalized.
Thank you so much for your help @BiancaK I really appreciate it :slightly_smiling_face:

You’re welcome :relaxed:

It’s easier to notice the blur on smaller fonts (your brain has an unconscious but super efficient clearing mechanism on larger fonts and texts). Doesn’t have to be exactly 12pt. You can use the FOCUS on the diopter calculator page or you can use a book (text book, novel, newspaper) that has the normal font size. If those give you about the same 39cms, good. If less, then you’ll have to define the starting point higher and work from there.

In the beginning, you may feel it to be too much in correction but that will be because you got yourself used to seeing a lot less details of the world. (There are advantages to that, too, just not for EM :wink:)
As I have put in my earlier post to sophie_p, you will need a vision that allows you to read number plates up to 20m or about 5 parking cars in a line, it allows you to be able to read the street and shop signs on the opposite side of the road, it allows you to walk into a café and read the menu above the counter, it allows you to read the departure times from the big display at the airport or at the train station. These are more important check points than the Snellen charts on the wall.
Or in other words, when you read honest 20/25ish on Snellen, you can read number plates and street signs / shop signs with those normalised glasses, too.

This is indeed the rule of thumb for starting the journey.


Once again thank you so much! :grinning: