How to reduce CYL?

Sorry for the clickbait title, I had to… :smiley:

I want a bit of clarification on this blog post about reducing prescription complexity.

I’m not sure how to interpret the idea of reducing the CYL for close-up first and later for distance.

  1. Should I reduce 0.25 for close-up and when I adapt reduce 0.25 for distance? (And repeat until no CYL is left)
  2. Should I wait until I’ve removed all the CYL for close-up (by 0.25 steps) and only then start to mess up with the distance CYL?

And the idea of tackling close-up CYL isn’t that violating the rule of having the same diopter bubble for close-up and distance (not monkeying with lenses)?

Actually, the whole EM method is based on monkeying with lenses, but only according to the guidance of the King Monkey. :grin:

This question has been asked quite often, and the answer of course is that astigmatism has a less distorting effect at close distances. En route to reducing prescription complexity we have to tolerate some monkeying about, and unavoidable changes in diopter ratios and sphere/cylinder ratios. And if we have a diopter gap, either in sphere or cylinder, at some point we will have to monkey around with that as well.

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Remember that Jake’s comment about not monkeying around has a follow-up of “until you know what you’re doing.”

If you have a complex prescription (including things like astigmatism and/or a diopter gap) there is no way you can make meaningful progress toward 20/20 without messing with the diopter bubble. However, it is important to read and learn enough to understand how and when to make changes. That way you can make the decision for yourself when you’re ready to try it. This is all a DIY process so plan to experiment a lot and expect to make some wrong choices now and then. Mistakes can slow you down, but what we’re doing is generally pretty safe.

In my case, I have the trifecta of moderately high myopia (minus sphere), astigmatism (minus cylinder), and a large diopter gap. So my path to 20/20 is going to be very different than most people’s path. I’m going to have to start “breaking the rules” (there are no rules, just recommendations) quite soon by beginning to equalize straight away in order to close the diopter gap quickly enough to get to binocular balance before I lose my differentials in the low diopters (or things will become harder).

In your case, it is up to you how you proceed. But the recommendation is to do your CYL reductions separately from your SPH reductions (and space the CYL reductions out) to avoid changing multiple focal planes at once. This usually means dropping 0.25 CYL in differentials, then 4-6 weeks later (or when you’ve gotten used to it) drop the same from your norms, then do two cycles of binocular SPH drops before dropping the next 0.25 of CYL from diffs, et al. You don’t need to touch SPH when you’re dropping -0.25D of CYL as part of a normal cycle.

Note: Since 0.25 CYL is hard to see, some people can drop 0.50 CYL in each cycle (which would be equivalent to a -0.25 SPH drop). But you’ll have to experiment to see what your visual cortex will handle.


Fair enough, and I should be ashamed of making a monkey joke - it was just too tempting (sorry Jake). You have the same trifecta as I have, but mine is at a lower degree of myopia. I leave all the monkeying around to my visual cortex.


I have the same trifecta and I feel you guys! :smiley:
Thanks for the answers, appreciate your help!


I have the same case…

Similar situation. And I am over 50, and no longer have the ability to focus on near objects. I started out in September with OD: -0.50 sph, -1.00 cyl and OS: -0.75 sph, -2.25 cyl. So I wear differentials for my work computer that have some plus component, and are under-corrected for cyl. by 0.5D. I found it immensely helpful to move my work space to the living room 55" flat screen and get more than 1 meter away (with differentials) and natural light. At first, I dropped sphere and gained even more cylinder. But over the last 4 months I have been reducing cylinder while holding sphere. Seems to be working so far. Currently: OD: 0.00 sph, -1.00 cyl and OS: -0.50 sph, -2.00 cyl. Right eye has improved from 20/40 to 20/30, which is pretty exciting. My next norms will have zero correction for the right eye. And I am contemplating putting +0.25 cyl into the next pair to try and pull more cylinder out. I’ll let you know how that works!

Hello Chris, your prescription seems very similar to mine:
R sph -0.25. Cyl -2.75 axis 80

L sph -0.50 Cly -2.25 axis 86

Working out what astigmatism I have was pretty easy when I realised I can see the horizontal but not vertical (atr). Just been getting great advice as I go and will be trying to drop diopter in both eyes… I think with the low sph values we have to tackle the cly,bit by bit. Some have advised to not focus to much on the differentials but may be an option.

One thing I do not want is to be reliant on the new prescription listed above lol…

Hello Jay,
I agree about tackling cylinder bit by bit. Even 1/4D drop is big I’m finding. I actually have 3 different normalized. I know Jake recommends limiting focal planes, but I feel like my case isn’t text book. I use normalized that are 0.50D under-corrected for cylinder for night distance vision, 0.75D under-corrected for daytime distance vision, and I’m experimenting with ones that are a whole diopter under-corrected when it is bright out and my eyes are rested and ready for the challenge.
I definitely need diffs for computer work, as I am pretty sure my astigmatism between my two eyes interact in such a way as to make it worse. My diffs are full-correction glasses with a pair of +1.00 readers on top of them. Looks ridiculous but I don’t care - I work at home. Being over a meter from the big monitor really helps. What tricks have you discovered?

Sadly I am still figuring out the best approach ,which is not the exact same for all. After trying to do my measurements I have yet to get the same or reduced diopter reading. I think with astigmatism any change or strain it can be magnified more so…sure this attunes for having floaters aswell. But my goal is to try and buy a smaller diopter and alternate between them.

Such a hard one to figure out