Can AF be achieved with monovision?

Hi Fellow EM’ers! I have high myopia and am getting started on my EM journey, which I plan to do with contacts and plus lenses for close-up work (i.e., staring at a computer for work). Unfortunately, I don’t do well with glasses.

I have a question that I haven’t been able to find the answer to yet on the EM blog, FB page, Jake’s videos, forum, etc. I apologize in advance for asking, if it’s already answered somewhere.

First, my Rx:
Contacts: -9.50R (distance), -9.00L (close-up)

My optometrist has been intentionally fitting my left eye at a lower strength to do the monovision thing for close-up. Without any correction, my left and right eyes are pretty even.

My question: Can AF be achieved with my monovision contacts? If not, then I’ll likely bump up the left diopter to get -9.50 in both eyes, and then wear plus lenses for close-up.

I’d love to hear your thoughts. Thanks!


Do you have an eye chart hanging on the wall somewhere? Set one up if you haven’t. You need to “take inventory” of where your eyes are right now with your current correction and you’ll want to see how you’re doing throughout the day. If you’re seeing 20/10 in your distance eye and 20/20 in your near-work eye you’re probably over-corrected to start with.

If both eyes are the same, and one is under-corrected by 0.5D, you’d have considerable distance challenge on your under-corrected eye, and could probably get some active focus challenge with it, but not with the fully-corrected (or over-corrected) eye.

I think for what you’re trying to do you’d be better off with equalized correction in both eyes, and use your plus lenses for near work rather than trying to do mono-vision. But before you change anything at all you should take measurements to see where you are right now and what you can see out of each eye.

You want to get rid of accommodation in your near work, so you can relieve any cilliary spasm that you have, and for distance you want just a little bit of blur challenge, but not too much. So maybe correction to 20/25 or between 20/25 and 20/20, but not 20/10.

If you find you can actually see 20/25 right now with your “near eye” with the -9 that might be a good starting point for both eyes.


It is generally adaptive for one eye to naturally be slightly better at close up, and the other to slightly be better at distance. Your eyes will already do that. Forcing this process to happen through adjusting the Rx is not recommended. If your glasses have a spherical diopter gap, anytime you take your glasses/contacts off, it will cause issues, headaches, slightly unbalance, etc… because (and i’m cutting out a lot of the nuance here but) your eyes were used to lights coming in unevenly and is no longer used to light coming in evenly.

There are plenty of people who have a diopter gap of -.5 and reduce from there without much issue. If you’re already accustomed to the prescription I’d leave it alone. At some point you definitely want to equalize the prescriptions though, and both your eyes and mind will thank you.

If you previously-recently had an equalized prescription, just stick to those and reduce from there.

Also, note nycmao’s comment about being mindful. You don’t want to overcorrect and you don’t want to undercorrect too much. Just 0.25 under whatever prescription you have.


Thanks for the feedback. I actually taped up several eye charts around my house. With my distance eye (right), I can see about 20/30 (and a few letters at 20/25 in the morning). With my close-up eye (left), it’s only at about 20/80, but even with that it’s pretty blurry. So the left eye is definitely under-corrected. Sounds like you’re saying it’s going to be a challenge for me to do AF with monovision. I tend to agree. Given that my left eye (-9) is so under-corrected, I think I need to bump up that side to -9.50 to match the right. It’s almost like I should wear -9.25, but I know that at this diopter range, corrections aren’t available in increments of 0.25.


I think perhaps the difference with my situation is that without any correction on, my eyes are pretty equalized. The 0.5D gap is created with my contacts on. The under-corrected left side (-9) is perfect for my close-up computer work. But the right side is over-corrected. With such a lopsided correction (seeing 20/30 on distance side, but only seeing 20/80 at best on the near-work side), I’m not sure I’d ever be able to achieve AF with my contacts on. Or maybe I can? I just have to keep trying. (I’m a newbie, so I hope I’m explaining all this right.)


We usually use undercorrected to refer to a prescription that gives you less than 20/20 vision. An overcorrection for more than that.

If I’m reading between the lines it seems that a -9.5 prescription would give you ~20/30 for both your left and right eye? If so, definitely start with an equalized prescription. You can definitely make do with a diopter gap but it will not be enjoyable.

I think your instinct is right that -9.25 would probably be better for you, but it seems that that is not an option? That’s unfortunate

We generally recommend people to wear their pair of norms until it gives them 20/20 vision, for safety reasons. Because this by large provides the quickest and smoothest gains for the average person. Some people do wear their prescriptions at a lower strength. It will involve some experimentation. I personally wear my norms till 20/40, and be able to make out 20/20 maybe even the 20/15 line.
This works for me most of the time, and for my daily lifestyle needs. Sometimes though my eyes tell me it’s too early to reduce, so I wait around longer before reducing. And there’s definitely value in enjoying visual clarity for at least a week before I make a reduction, that way my body isn’t freaking out about being in a constant state of blur. The more experience you get with how your eyes are feeling you’ll get a hang of that too.

Probably just get a pair of -9.5s and a pair of -9s. You’ll get to using the -9s eventually, even if you find its too early to use them now.


If you’re seeing 20/30 with -9.5 contacts that sounds like a good starting point. Wearing your +1.25 plus lenses over those at work would take you to -8.25 D, which would give you a range to bring the screen a little closer or further away to get your cilliary muscle to relax all the way. Once the strain is taken off it you should be able to active focus a little bit at distance in the -9.5 contacts, when the cilliary muscle is relaxed it would probably take you from 20/30 to 20/25 or better with the -9.5 contacts in. Then you’re on your path, with the monitor moving further away on your desk, seeing a little better through the contacts at distance… before too long you could probably drop to -9 contacts and bring the monitor back in closer again.


Thank you, to the both of you, for your EM wisdom and advice! It’s so much appreciated. This forum is awesome, with so many people here to help others.

When I’m no longer a newbie, I hope to give back by offering my help to others one day. But for now, I think I have a path forward now! My journey begins! I’m excited. :grinning:


Actually, I have both those already. So I’ll just wear my - 9.50D lens in my left eye, as opposed to what I’m doing now, which is wearing the - 9D lens in my left eye. I believe my right and left lenses are interchangeable, in terms of diameter.


It is a trending solution (surely in Europe) “invented” to avoid wearing bifocal glasses, and especially to avoid wearing bifocal contacts as those would be rotating on your eyes with every blink. However, as @AznDudeIsOn mentions this creates an artificial gap between the eyes and plays tricks on your brain whose task is to merge the 2 images received from the eyes… EM doesn’t recommend using bifocal or multifocal glasses, so I would say EM doesn’t recommend using your eyes separately to imitate bifocal corrections either.
The opto suggested gap is tiny in your prescription. A lot of people would have it as a gap built up during the normal opto prescribed myopia progression. So best not to teach this monovision technique to your brain and use normalised and differentials instead. In your case contacts and plus glasses in front of contacts.


:thinking: this wasn’t intentional :joy:


I have a gap of .75 and have maintained that for the 1.5 diopters I’ve dropped. This actually works out to drop both at the same rate because when you drop 1-1.25 from Normalized to Differentials (far and close prescriptions), you can automatically RE-use your Diffs as Norms.
I imagine when I get close to the end, I’ll then work on the weaker eye independently (at that point, I also won’t need Differentials!!! :star_struck:)

btw, I started at -6 and that eye is now at -4.25, so I still have some ways to go before worrying about that.


I’m encouraged by the progress you’ve made. Congratulations! :+1:

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Jake mentioned to me that there might be a section on the board for monovision, in future. Meanwhile I’ve been in monovision contacts for quite some time and though its not recommended for ending myopia, have successfully reduced with them.

For me the key was getting a normalised prescription for my monovision lenses, with plus 1.25 over them for screen use, and with everyone’s help here a correct set of differentials when my contacts aren’t in. Also a few minutes of patching at bedtime when I read on my kindle with the differentials…

I was able to reduce about 2 diopters over a few years. I’ve a large gap and wish I didn’t, but AF still works. Good luck to you!


Just a clarification: Are your naked eyes equalized and the contact lenses are different in each eye to intentionally create monovision? Or are you saying that without any corrections on, one eye is weaker than the other, but with contact lenses on, they are equalized? Sorry if this is a stupid question, but I just want to make sure my definition of “monovision” is the same as yours/others. Thanks.
BTW: My condition is the former.

Hi Linda-L,

Not a stupid question at all. No my naked eyes are not equalised. My L eye was always somewhat weaker (not sure how much). My eye dr. always gave me normalised lenses and she equalised those. When I got presbyopia, she set up the contacts in monovision so that my L (weaker) eye was the reading eye and the R eye was distance. Once she did that, she taught me how to do AF in the exam room. and then my L eye improved to less needed diopters. I went from somewhere in the -5’s to -4.0 (L eye) over a few years. My R eye also improved until it got a cataract but that’s a different story. Main thing is, with monovision it still works but I think slower.

For glasses, my eye dr gave me normalised “distance only” and differentials for “intermediate only”.

I think in your case you’re lucky to have equalised eyes and you could just use + glasses for screen and reading, instead of needing monovision.

Hope that helps!

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Thanks for the clarification, Meri. It’s good to know that AF could be achieved with monovision. But, like you said, it would likely be at a slower pace, which is why I stopped doing the monovision thing by just wearing the same diopter contact lenses in both eyes. As for being “lucky” to have equalized naked eyes, that’s probably the only lucky thing about my eyes. I’m not so lucky when it comes to having high myopia. :frowning_face:

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