Average Time period range for an Equalization step?

For anyone who has done an equalization step, how much time did you find you needed to go down 0.25 in one eye, from the time you made the change until you were ready for your next regular lens reduction? How did this time interval compare to your previous regular reduction interval? How did you know you were ready to do the next binocular reduction after equalizing and confirmed it had worked? Did you use any special methods? What time of year was this In terms of season and light level? How much outdoor time? And what was your myopia level at the time? How successful was it overall, looking back? What, if anything interesting do you recall from the equalization process? Do you feel you were better off after? What might help or hurt an equalization in progress?

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@MattE laid it out nicely in his diopter angst video:



I started with -5/-2.25 L -5/-3 R
after successful binocular reductions to -4.25/-2.25 L -4.25/-3 (average of 4-6 weeks per reduction)
i started equalizing (not in the endmyopia recommended way)
First i reduced my CYL (i was pretty new to things, i assumed i am over-perscribed, thinking back, i think this was a mistake)
-4.5/-1.75 L -4.5/-2.25 then: (notice equalizing 0.25 CYL while also replacing 0.5 CYL with -0.25 SPH)
-4.25/-1.75 L -4.25/-2.25 then:
-4.25/-1.75 L -4.25/-2 then:
-4/-1.75 L -4/-1.75 then:
still, average of 4-6 weeks between reductions
the last reduction (equal perscription) took a long time to get used to, and the glasses got a bit crooked because of my kids so i switched to a:
-3.75/-1.75 L -3.75/-1.75 R
was stuck here with no progress for 2 months,
then switched back to
-4/-1.75 L -4/-1.75 R with a different frame
currently still using this for 80 days.
i can see 20/40 well with my left eye, and 20/50 line with my right eye.
i think that i equalized too quickly, and reduced too much CYL, so now suffering from double vision.
i’ll wait for summer and keep reducing. if it will not go well, i’ll add SPH to the right eye, about 0.25 so that both eyes can see 20/40 line easily. if that won’t work i’ll probably need to add some CYL back :frowning:


I started at -2/-1.5, had my prescription reduced by an ophtalmologist at -1.25/-0.75, 3 months after I found Endmyopia.
I was at the point where you can try to go without glasses on sunny days and I felt some discomfort when putting the glasses on or off due to the diopter gap. I could also feel the right eye was clearly the one the brain was using in first place. So after some reading on the website, I decided to start equalizing.
I reduced 0.25D in the left lens in the beginning of spring 2018 and did some patching (15 min/day). No other special method used, apart from checking regularly the cm measurements (sometimes on the Snellen with glasses on). It was hard to force the brain to use the left eye and the results in cm were really slow. At first, the brain was like “Nope I don’t want to use this one, it can’t see well”. I was really struggling to achieve AF with this eye alone. It got slowly better and I could feel the brain using more and more this eye too, even when looking with both eyes. It was also difficult because the dominant eye was clearly ready for the next reduction and I had to wait for the other one to catch up.
After 4-5 months my left eye was finally comfortable with the -1D lens and the reduced gap. The edge of blur for the left eye was at more than 100 cm and with this eye alone I could see 20/20 on Snellen with good light. So I decided to make a second 0.25 reduction in the left eye only. I did not make any bifocal reduction inbetween. In my situation it made not really sens to go deeper in the low myopia territory with the right eye and still having to deal with the diopter gap. The goal was to have no focal plane change between naked eyes and glasses, which was the case after the second reduction. With the equalized prescription it was really better, no discomfort or strange feeling anymore when taking the glasses on/off. Still difficult to gain some cm with the left eye and a lot of DV to solve in this eye. I think it was a good idea to equalize in spring and summer. I’m sure sunny days helped a lot and I was probably more outdoors at these seasons.
I had to wait the whole summer before only thinking about reducing to -0.5 for both eyes (it is a big jump between -0.75 and -0.5). I made this bifocal reduction last October. Again with some occasional patching to be sure the left eye isn’t lagging behind. With hindsight, I think I could have waited some more time before reducing to -0.5D, considering the lack of light in autumn and winter, but that’s not really related to the equalizing process.
Both eyes are now comfortable with this lens power and I have almost the same Snellen results or cm measurements with both eyes :slightly_smiling_face: Still slightly more DV with the left eye when I go glasses free, but easy to fuse.
Equalizing took me more time than the first bifocal reduction and it was quite hard work. I had to be very patient, even if it was frustrating when my cm didn’t seem to move…
I think it is easier and less stressful for the brain if you can do a bifocal reduction after each equalizing step, like Matt explains in his video. It might also be less difficult if you start equalizing (of course only after having done 1-2 successful bifocal reductions) when you have average myopia, because the gap in cm between the diopters are smaller than when you have low to very low myopia.


My thoughts, too. In fact, my current project of increasing my lens power monthly (since I used to under correct drastically) is having a side effect of equalizing the eyes slightly (keeping the 0.25D diopter difference). I will be done with this in June, and then plan to do my last equalization.

My last completed binocular reduction was a long time ago (years ago…before I got totally off track and then later found endmyopia). I am currently in the middle of a very slow combo equalization/binocular reduction as mentioned above, which will probably improve my average diopters only by 0.12 or so. It’s hard to explain, but if you know my history, you understand why, and it makes perfect sense what I’m in the middle of right now.

I will be ready for (my final 0.25D) equalization the beginning of the Summer, and will use my peak lens power to its advantage to tilt the momentum even further toward equalization, naturally. I am really hoping to spend no more than 6 weeks on it after equalizing, as I will be wearing a full correction in my other eye during that time, and the sun will be peak intensity for the year.

I also don’t want to fall into the trap of running out of sunny season and not being able to do two more binocular reductions before Fall and Winter (since it seems impossible to do anything all from late Fall to late Winter). Even if I can fit those two in after the equalization between August and November, I will still be wearing something fairly strong (-3.25) in both eyes all Winter if I can’t progress during that time of year.

Far future: If my eyes drift apart again, and I need to, I can always go back to a 0.125 or 0.10 diopter gap someday in the future when I have low myopia/emmetropia (assuming I find a laboratory that will make glasses in those increments), and then equalize again, eventually.


I was in the same situation and a little worried about this too, but from my experience the dominant eye was just put in a waiting position and I’ve seen no bad side effects. It was just super ready for the next reduction when I finally made it! :grinning:

Seems like you have a good plan :wink: I hope it will work for you!

Just to clarify, this statement was not really meant for you (you’re a special case anyway). It was more generally speaking, especially in case some newbies stumble upon this thread :wink:

I believe you’re overthinking :smile: I see no reason why your eyes would drift apart again if, after having equalized, you take care to make your bifocal reduction when both eyes are ready. And it is normal that both eyes never have exactly the same acuity. A little difference (up to 0.25D difference in your cm measurements) is acceptable in view of the ocular dominance, with no need to increase the non dominant eye’s lens power. It’s usually because some optometrists don’t take into account this biological principle that you end up with an unequal prescription and over time a lens induced (increasing) diopter gap. But you shouldn’t encounter this situation :slightly_smiling_face:


@Sandra, thanks for clarifying.

Now, I’ll clarify a bit more, too.

My dominant eye is the one that has the higher lens power. I’m not sure if most people are that way, or not. I know it can change over time based on what optometrists do, so I don’t know if there’s really a connection. I know that with some people, it’s their non-dominant eye that has the higher power.

A little aside on this topic: When people have early presbyopia, I’ve heard of optometrists intentionally under correcting the dominant eye only by 0.25 to 0.50 to create a monovision type of situation (not true monovision, which requires at least a diopter of difference, but similar idea). Personally, I think this (or anything else that needlessly increases a diopter gap) is a bad idea. They really should just under correct both eyes instead of one. Just goes to show there are lots of reasons why one eye can end up higher than the other.

Back to me. I figured out that one reason I currently find it more difficult to achieve active focus in both eyes at the same time is that difference in lens power between the right and left. Until this is sorted out post-equalization, binocular active focus is going to continue to be artificially more difficult than it should be.

I have worn the same power in both eyes several times over the years; the most recent being 10-15 years ago when I was wearing -5 in both eyes. Before that, I wore -3.25OU as a kid in grade school for a few years. Everything else before, in between, and after had at least a very slight diopter difference (0.50 being the diopter gap I spent most of my life with, until a couple of years ago when it finally went down to 0.25).

My highest diopter difference ever was 0.75 back in the mid 2000s, and this was actually the result of a mainstream eye doctor’s poorly-thought-out reduction when it turned out I no longer was as nearsighted as I was before.

I attempted to cut this down to a 0.25 difference a few years later, all in one step, because I didn’t know better back then. Not only that, but I did it while primarily wearing differentials almost full-time. That was a poor recipe for success, and there were many extra headaches and things of that nature for a couple of years while the system equilibrated. I also jumped back and forth between glasses of various diopter ratios through 2016, which I now know is a bad idea. I used to think splitting the difference would help the system average out. In the end, I was eventually successful, but I didn’t realize how bad an idea that was until I found EM. My advice for anyone now is, once you change the diopter ratio, assuming you can tolerate it, don’t ever use glasses with a larger gap again…let alone while equalizing.

I’m looking forward to doing things “by the book”, and having a much easier time than I used to.

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Yeah, maybe I’m overthinking. Maybe not. The idea is that natural usage and ocular dominance, as well as possible incomplete (less than 100% equalization) might result in there still being a diopter gap in the future. I just was saying that if that happens, and if that small difference (less than 0.25) becomes a nuisance when I’m in the emmetropia range eventually, I will find a way to reduce it again. That’s all. Just like it’s a nuisance right now, it could be a nuisance again someday when it comes to being able to focus properly (onset of presbyopia, etc.)

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Very interesting. Was your sphere always the same? I have not heard of such a starting point often, same sphere and different cyls.

It sounds like it went pretty quickly for your first few reductions, including the first couple of cyl equalizations. I also find it interesting that you did not feel the need to convert each and every cyl increment into sphere prior to equalizing it, though you did something similar at least once when you converted to sphere.

How long did you stay at the damaged power (before damage occured) before having to switch to the next lower one? Did you want to switch back to that previous power sooner, but couldn’t get a replacement for two months?

Add that duration to 80 days, and what is the total time spent at those two powers combined?

When you say wait for Summer, how much longer are you willing to wait and how much time are you willing to let go by with possibly no progress?


I have an interesting situation currently.

My brain favors my right eye, which is the dominant eye and also the one that is 0.25D higher in lens power. It actually sees better with correction than the left does, while the left sees better than the right by a tiny bit without correction.

The cm values are very similar, with the left cms being slightly longer/less myopic, but not by much at all.

I am looking forward to equalizing again. Though it might be tough initially, I think it might actually help with the (brain’s) visual unevenness over time. Did you find that to be the case (that after a while your brain stopped favoring one eye as much and that achieving active focus in both simultaneously got easier)?

Unfortunately i don’t have my prescription history before i started endmyopia, i only know that it stayed the same for more than 5 years (i’m 33 yo now, and this is the first time my prescription is not increasing)
i guess it is because i finished studying and started to make more breaks during work (9-5 screen time work)

I didn’t want to change the SPH initially because i thought that i can get rid of the CYL alone and equalize it, which doesn’t look like its working like that - i actually notice that my weaker eye (eye with more CYL) is improving slowly it’s SPH and it seems that my eyes cycle during the day in terms of who sees more clearly (i guess my left eye gets tired then my right eye takes over. this phenomena was much more frequent before i equalized. now it is less frequent so i guess my left eye needs to get really strained in order for them to cycle)

I stayed with the “damaged power” 2 months which was terribly blurry, then i switched to my current prescription which i am making progress with, albeit slowly. (to total of about 120 days since my last “successful” reduction, which also happens to be the entire automn-winter time.)

Now we start to have much more sunny days. Today we have a clear day and my cm measurements in the left (dominant) eye improved by an amount equivalent to a 0.5D compared to yesterday. (CYL didn’t change much) i spent about an hour staring at the trees this morning :slight_smile:

My current plan (although i don’t think i’ll have the patience for it) is to keep wearing my current Normalized until i stop progressing (1-2 month of no progress) i want to do that so i will have a better experience and less blur / double vision, otherwise i might find myself with the previous “damaged power” again making no progress.

In the meantime, i’ll keep reducing my Differentials, and i plan to convert the remaining 0.75 CYL to SPH so i will have a SPH-only differentials. If that works i might start converting CYL to SPH in my Normalized (although my understanding is that the endmyopia way is to reduce it gradually… so i might play by the rules to be safe… i just find it hard to resist trying / experimenting in getting rid of the CYL altogether)

Looking forward to summer time :slight_smile::slight_smile::slight_smile:


I’m in the opposite situation, my dominant (right ) eye is the one which is slightly less myopic so not sure if what I experienced can entirely apply to you.

For me, even before equalizing, I believe I had no real problem focusing with both eyes together (once I understood how to active focus). Perhaps did I not pay enough attention that the brain wasn’t really using the two eyes equally? However, I can feel the brain using more the non-dominant eye since equalizing. So yes, I can say the two eyes are now more working together, but still not perfectly. I think it is normal if the brain keeps favoring one eye just a bit.

From what you explain, the difference between your eyes’s acuity seems really small, so the 0.25D more in your dominant eye is probably not necessary. It is possible that the diopter gap is what bothers you when focusing with both eyes (could it be that the brain is confused by this extra amount of minus in the right eye?) You probably won’t know for sure until you have equalized and tried with the equal prescription.

What surprise me is that your right (dominant) eye is the one which sees better with glasses, but that the left (non-dominant) eye sees better with no correction. My dominant one always sees a little bit better, without or with glasses (when both are corrected at equal level) :thinking: It goes back to what I said above, your right eye perhaps already doesn’t need this extra 0.25D?

You’re definitely an interesting case :grinning:

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For the most part. The catch is, the right is also more prone to fatigue/ciliary spasm, so sometimes it gets worse than the left even with glasses. (I need to get away from this screen now…it’s starting.)

I think I’ve favored the right so much the past few years (without realizing) that it become more dominant than it had been.

To complicate matters even more, I tried equalizing about a year ago, and failed. I just was not ready. I will be ready this Summer, though.

Looking forward to equalizing.


Played around with my test lens kit, trying to figure out how many diopters i would need for best vision without astigmatism. Can bearly see 20/50 line with the best sphere.

I guess i would stick to the slowly-but-surely approach and lower my astigmatism that way.

I also noticed that my dominant eye is much more ready for reducing, but i’m afraid to increase the diopter gap even more… (i thought about changing the lens of my left eye, and only lower it by 0.25D, maybe i would give it a week and see if it encourages the brain to use the right eye more)

Just felt like sharing :hugs:


Couldn’t resist reducing my left eye by 0.25
So I’m now at -3.75/-1.75 L -4/-1.75 R
Now both eyes see approximately the same snellen line, left eye still feels better with less double vision.
We’ll see how it goes…


hello Itamar, maybe the problem is that you have done several cylinder reductions in a short time? I understand why you want to address the cylinder (cause it’s quite high) but I think I read that cylinder reductions usually take longer to adapt to, don’t they?does this make any sense?

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Yes @JuliaBcn
I reduced CYL too quickly and also equalized too quickly.
I think i would add back some CYL if it will not go well.
My current plan is to focus on reducing SPH this year and see how it goes


Ok! Sorry for the maybe silly question but when you say 4-6 weeks between reductions you mean 4-6 weeks new normalized, then 4-6 weeks new differentials , 4-6 weeks new normalized etc , right?

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Initially i didn’t know about alternating norm/diff reductions, i just reduced them at the same time or when i noticed a big enough improvement

Now i realized i was reducing too quickly… i just made an eye test at home with my test lens kit, which agrees with my cm measurements, which is around -4.5/-2.5
But i am wearing -4/-1.75 norm and -2.75/-0.75 diffs so i am undercorrected, especially the astigmatism component…
And i am experiencing slowed progress, especially in the weaker eye which has between 0.25-0.5 more astigmatism

If this will not improve in the next few months, i think i will start from the full perscription and reduce more slowly, now that i felt the pain of reducing too quickly, maybe it will help me have more patience between reductions… and of course alternate norm and diff reductions separately


I have -1.25L and -1.75R.If I am going to have 2 bifocal reductions then reduce in one eye then have bifocal reduction again,I would go to deep in low myopia. I need some suggestions.