# Rate of improvement and relationship to cm

Hello everyone. I have a question related to the mathematical relationship between cm measurements and diopters, and how this manifests in real world improvements.

Out of curiosity, I plotted a simple graph with cm on the vertical axis (starting at 0 cm and increasing upwards) and diopters on the horizontal axis (starting at 0, then increasing to -1,-2, up to -8). What I found was an inverse exponential relationship (I think! Been awhile since I’ve done math in school). That is, higher diopter cm differences are much smaller than lower diopter cm differences. For example, the cm difference between -8 and -7 is only a few cm (around 3?) whereas the cm difference between -2 and -1 is like tenfold that, around 40 or 50cm! Because of this relationship, I cannot see how both the rate of diopter improvement and cm improvement can BOTH remain CONSTANT without one or the other accelerating in relationship to the other variable at some point. Which leads me to the following questions:

Does the expected rate of improvement hold constant at 1 diopter a year? If so, as one gets closer to 20/20, does the rate of diopter improvement remain constant, but the rate of cm improvement drastically accelerate?

Or is the rate of cm improvement constant, but then the rate of diopter improvement all of a suddenly accelerate as one gets lower and lower diopters?

Or, does the rate of one of these variables actually slow down as one gets closer to 20/20?? For example, do cms improve at a constant rate but the decrease in diopters all of a sudden slows down to a snail’s pace? (This scenario seems to reflect how Jake said reducing the final diopters can be the hardest - pretty sure I read that somewhere.)

Perhaps those of you that have made significant reductions from high to low myopia can chime in as I’m very curious as to what to expect. I started at near -10 about 2 years ago and am at -6.5 now. Thanks to all those who respond!

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Now that I actually read my graph again, it seems to suggest that if cms improve at a constant rate, the rate of diopter improvement drastically slows down as you get closer to 20/20. I think I answered my own question lol

So then this implies that as you get closer to 20/20, is it true to say that one can no longer expect improvements at the rate of 1 diopter a year? What is the expected rate then? And realistically at what point in the EM journey from high myopia does this “1 diopter a year” expectation then no longer apply?

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Logarithmic functions = inverse exponential functions.

This makes sense since we are told that we improve faster in the beginning and slow down at the end. I think this also explains why some higher myopes improve at a faster rate than people with lower myopia.

Logarithmic! That’s the word I was looking for thanks!

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Yes, until around -1.5 D.

Exactly.

Yes and no The experience is that below -1.5 D the journey changes and what worked smoothly before does not work as smooth anymore. Most likely you need to change up habits, try going without glasses, etc. The why is unknown currently, but because of this bit habit change and experimenting it definitely slows down. But until then the 1 diopter per year should be constant.

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Optically, just like with focus on a camera lens, there is nothing “magical” about 20/20 or approaching infinite relaxed-eye focus. Just like with most modern camera lenses where you can focus past infinite when in manual mode no differently than any other focus distance, the eye’s calibration doesn’t “slow down” with focus distance. It’s all just bending light, changing cornea/lens curvature and adjusting eyeball length (moving the “sensor” forward).

Why things might slow down is more basic. Two things to consider are the eye’s calibration range (think of that camera len’s focus range) and the opportunities to stimulate both myopic and hyperopic progression. Many of us progressed in myopia and then “stabilized”. That is because we reached the limit of our calibration range with the myopic stimulation we were feeding our eye’s calibration mechanism. So it’s possible going the other way you can hit a limit too. Progressive hyperopia “stabilizes” with far sighted people too.

But I don’t buy that the limit is just coincidentally infinite focus. I think the slowdown in improvement at low diopters is mostly something else. Up to that point, close up viewing required either negative glasses or naked eye. At the 1.5 diopter mark, your relaxed eye focus is 66cm away, beyond reasonable handholding distance. Viewing closer than that requires either close up focus or plus glasses. Close up focus is what turns on the myopia calibration mechanism, which (in my opinion) starts to retard and even stop the improvement process. It is my belief that low myopia close focus requirements get in the way of improvement, and is the root cause of the problems with the “last diopter”.

The solution I’m hoping that works for me is plus glasses. That’s the way I hope to get through to infinite focus (and beyond, for sharp night vision). But it’s controversial here. Jake has said some of the people he’s worked with myopia reversal who tried plus glass has weird double vision issues. Thus he doesn’t suggest it, and it’s gotten to be a taboo thing in these forums (some feel that plus glasses might cause more problems than they solve). So it’s up to you. My plan is to use plus glasses once my myopia is low enough to keep the momentum. It would be a shame if that doesn’t work, as I see no other way to get to 0.5 diopters of hyperopia, which I need to see stars at night as points with a fully dilated pupil, which is my dream.

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The plus glasses thing was not encouraged in part because Todd Beker’s famous advice had everyone reaching for them as a quick fix. People leap for them before they are anywhere near ready, before they understand their eyes, before they know how all this really works. I have been binge listening to the short-sighted podcast episodes (5 today) and Jake does give people with low myopia, who know what they are doing, encouragement to use plus lenses - although only if he knows their experience with EM and won’t try to use plus lenses as a quick fix, or as an excuse to continue unhealthy habits like some magic elixier. I reckon if you were in a position to have a good ole fireside chat with The Jakey, he would be supportive of your plan of attack. (Listen to the episodes with Alex and with Matt if you want to hear Jake’s advice to them and see whether it helps you. I know I listened most intently).

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Yes I agree, plus glasses are not a quick fix, and if misused, can be as bad as negative lenses (as we all know). That’s a good point, thanks for the clarification.

As usual, it’s all about the basics, namely managing the edge of blur, and using active focus while avoiding close focus accommodation.

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Diopter simply means the distance to blur

If you measure the distance to blur and put it in the calculator you will see how many cms you have to improve within each 0.25D lens power.
-2.00D = 47 to 53cm
-1.75D = 53 to 61.5cm
-1.50 = 61.5 to 72.8cm
-1.25D = 72.8 to 88.9cm
-1.00D = 89 to 113.9cm
-0.75D = 114 to 159cm
-0.50D = 160 to 266cm
-0.25D = 267 to 800cm
-0.00D = 800cm and above

It is around -1.75D when you will feel you don’t need corrections close-up anymore because your blur line is now over the comfortable close up distance but you still have room to get further away from the monitor. (This may be slightly different if your glasses have / had cyl, too)
-1.00D starts at 89 cms and typically it’s just not realistic to sit much further away from the monitor than 90 or 100 cms. So your close up stimulus is gone and you will have to work harder for it that’s why you slow down in the last diopter.
But the good news is that while you are working on pushing the edge of blur from 1 metre to 8 metres the texts and objects you want to see get bigger. You wouldn’t try to read a page of a normal book from 6 metres…

Having said these I’m someone who went down to 20/20. It’s been 18 months since I had my fully clear days with distance vision without wearing any corrections. I experimented with plus glasses at 3 different times (at the first 3-month plateau, last summer and this winter) with Jake’s recommendation and I learnt that plus glasses are just not for my eyes…
It’s a technique to keep in the back pocket, especially for long real plateaus during last diopter, but it isn’t a magic shortcut.

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Out of curiosity, when you say the plus glasses are not for your eyes, what do you mean? What was your experience? Did you just not like the views of closer things through the plus glasses (distortion, etc), or was there some artifact or visual anomaly that you saw? Also did you use Zennis (or equivalent) glasses?

I’m still a ways away, likely 1.5 to 2 years before I’ll need plus glasses to ensure blur challenge at work with my monitors, but am curious what your experience was, and why you found them not for you.

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First time I used them too early. I had the vision improvement in the summer in a sunny country on a long holiday with limited screen time and winter was much darker with a lot more office work. I thought I was at a last diopter plateau but actually it was still very much a work in progress within the last diopter. So I simply stepped back to a higher normalised correction.

Last summer it didn’t feel good at all. I’ve always hated wearing glasses. I didn’t like the bigger images the plus lenses gave to me. AF in them wasn’t a good feeling. But I used them on my walks, popping them on for 15 seconds and then getting a slightly clearer distance vision for a couple of minutes. After a few weeks I put them in a drawer and I completely forgot about them.

This winter I tried them again. It felt different. They gave me some close up challenge finally. I didn’t AF, just let my eyes relax extra. I’d say it slightly nudged my non-dominant eye maybe. As I avoid small screens and close distance with screens, novelty wore off after a few weeks and I didn’t experience any real advantages so they landed in the drawer again. But the truth is that eyestrain in front of the monitor has never been an issue for me really. Wearing them indoors gave me dizziness as in plus glasses I really felt that it is only the screen’s distance I can see clearly and nothing more.

I experimented with +0.5D and +1.0D, with a little effort I could get crisp clarity on the screen with both. I bought them in the pharmacy after trying all of the glasses on (yes, it was before covid-19.), but I don’t think that makes them less than Zenni glasses.

And while they didn’t work for me, I developed an idea why it may work for others if applied correctly and at the right time:
I have never worn minus glasses either. I wore contacts always. Always! I chose going out uncorrected holding on to someone’s arm sooner then putting glasses on if for any reasons I didn’t want to wear contacts. And I was OK uncorrected when at home.
My theory is that it’s less the plus power and more the PD guide for the eyes. With contacts my eyes were never guided what position to take. With glasses you have the PD and that’s the clearest part of the lens. So when you hit zero correction you have one more task: train your eyes to keep the PD even without glasses.
That’s where I believe the plus glasses can be helpful to a certain extent to some people when applied in a certain way. But in general I don’t recommend wearing plus glasses. Certainly not before getting to real 20/20 uncorrected.
Definitely not a panacea to speed up improvement in the last diopter.

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Thanks for the clarification! Yes, I can see that if you’ve never worn glasses, the distortion is an issue. Back when I wore contacts, and started using plus glasses for eyestrain control, the cheap plus glasses I were using had three big issues: 1) distortion, 2) magnification (as you mention), and 3) no coatings, yielding reflections. For comfort reasons (mostly allergies, but also dry eyes), I fairly soon dropped contacts altogether (after 10+ years of using them), and went all-glasses. Thus I started using my PC glasses of lower power than full-blown, essentially my first diffs

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This is not coming from the plus glasses, nort a distortion. It’s something I developed more awareness for. With every drop when the acuity reaches 20/20 or better I feel that objects have jumped closer, things that seemed to be far away now seem to be closer. Best example is a fairy tale cottage on my favourite walk, I’m sure nobody is pushing it closer to the road as my eyesight is improving, but still now it seems bigger, most probably because I can see a lot more details clearly and because of that I find it difficult to take in the whole image in one…