Having trouble getting used to no cylinder

Hi folks,

I recently went to an optometrist and I came back with this prescription:
OS -4.75, -0.25 cyl axis 105
OD -5.25, -0.5 cyl axis 30

(I previously had OS -5.50, no cyl, and OD -5.50, -1.25 cyl axis 60 = my eyes improved both sph and cyl after my first differentials!)

So seeing how little cylinder I had now, I decided to order my glasses ditching the cyl and not changing spherical: OS -4.75 and OD -5.25, and see what happened as many of you I remembered could drop it with no problem it being so low. I also tried that new no cyl prescription with my contact lenses for a few days last week and was fine.

Well, I started using the new glasses last night for the first time and I get dizzy and nauseous, and feeling some strain. Today I could tolerate them better but I still feel nauseous because I can see crystal clear through my left eye and my right eye can’t due to its 0.50 cyl.

So now I’m sitting here wondering if I did something stupid, and should had ordered the glasses including those low cyl corrections instead, or whether this is normal and my eyes are just trying to adjust and should give them time.

So I guess my question is: was I reckless trying to go no cylinder? I thought about compensating the 0.5 cyl in my right eye with spherical (making it -5.50 instead of the -5.25 sph my eye exam showed) but really wanted to see if my eye noticed the change.

Would love to hear your thoughts on this, or whether anybody has had a similar experience with such low astigmatism. Should I give it time and see if they adapt? Or is it wiser to reinclude the cyl for distance? I really wish I had tackled the cyl on any diffs first instead.



I would stick with the no cyl glasses. The reason you were feeling dizzy and nauseous is because your eyes were resetting back in place, for lack of a better term. You should be fine moving forward.


@Mintaka, it sounds like you reduced too quickly. I like the optometrist’s rx (other than the brand new new cylinder power in the right eye…why now, if you never had it???)

Remember that your starting power spherical equiv. was:
OD: -5.50 and OS: -6.12.

And the optom decreased you (maintaining the original diopter gap) to to an equiv of:
OD: -4.87 and OS: -5.50

Meanwhile, you reduced to:
OD: -4.75 and OS: -5.25

I bet now you instantly can see what likely is causing your discomfort…likely that extra 0.25 reduction, 0.12D change in diopter ratio, and 1.25D change in astigmatism correction all at the same time. No harm…just discomfort, worse vision, and possibly reduced progress. Maybe you’ll adapt to it, maybe not. It’s not like it’s a giant change. Big, but not gigantic. See how it goes for a week or so, unless you really can’t tolerate it after a few days. :slight_smile:

I hope I didn’t misunderstand, by the way. It sounded like you were wearing the stronger distance glasses with 1.25 cyl that you listed, before the recent visit. Is that the case? My whole post was based on that premise! If not, I take back the whole post.


As FMR said, it can be the change in diopter ratio or the change in cylinder correction or everything together.
Just to give you an example from my experience although it doesn’t include cylinder correction:
I’ve always had a diopter ratio of 0,25D. Last summer I tried to equalize as the eye with the stronger power was seeing slightly better and also doing more Active Focus than the other eye. So I equalized differentials and normalized glasses and also contacts which I only use sometimes outside for a couple of hours.
So what was the result:
with contact everything was fine
with differentials it felt a bit weird but still ok
with normalized I felt dizzy - but after a few days the eyes and the brain adapted.
(only problem was that I wasn’t able to do AF anymore so after 3 weeks or so I went back to the previous glasses - will try again later on)

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Hi @FMR,

Yes, you understood properly. :slight_smile:
My previous glasses had -1,25 cyl in OD. I also wondered if it was my visual cortex complaining about “where’s my cylinder drug!” after changing to no cyl altogether.

Where did you find how to calculate the spherical power in the blog? Would love to learn to do the same.

I’ve had worse days and better days, since I started using them tuesday evening. Sometimes I feel fine, and sometimes they are unbearable. Still haven’t got used at all to them yet, but I have already noticed that my 0,50 cyl eye (OD) has already improved a little :open_mouth:
Whenever I close the left eye, I realized I could have clear flashes with the right eye for seconds at a time if I practised active focus: all that astigmatic blur would shortly go away.
So despite the dizziness I feel most of the time, my right eye is “waking up”.

I can also see better without glasses already compared to when I did take them off with the older prescription.

It’s my left eye (my stronger eye) the one “complaining” and trying to make sense of the new focal planes. It is the one feeling the strain now.

I sometimes wonder what would happen if I dropped a little 0,25 sph in my left eye, making both eyes have the same diopter ratio as before. I mean somehow making both eyes have the same degree of blurriness, if that makes sense. Not having one eye with crystal clear vision and the other not. As I’m afraid of including the cyl and starting that cycle all over again.

The optical shop kindly told me anyway that if I needed to change my lenses or prescription down the line, that they would do it free of charge (I have a month for that) if I was unable to adapt. I had gone there today to check if my glasses had any manufacturing flaws just in case, and they came out fine.

They agreed it is probably my eyes trying to adapt and also advised like you did to give it some more time. I have a feeling it is the changed diopter ratio causing this, not only cyl.

So I will try to stick with this prescription for a week or so before deciding anything else and see what happens. :slight_smile: I will try to update as soon as I can! :slight_smile:

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Hi @Mintaka. Nice to hear it’s going well now.

The spherical equivalent is calculated as follows:

1/2(Cylindrical) + spherical = spherical equivalent

In other words, cylinder counts as half the power of sphere. This is because cylinder by definition only has full power in one axis (e.g. horizontal), and no power in the opposite one (e.g. vertical). So the average power of just a cylindrical power is the average of its full power and zero. In other words, full power divided by two. So, if you have 0.50 cyl, the average power is (0.50 + 0) / 2 = 0.25

And 0.12 comes from half of 0.25. It’s actually 0.125, but in eyeglass land, it’s rounded to 0.12 for whatever reason.

How are you getting along with the optometrist’s correction? It sounds like it’ll make a really excellent first normalized to me!


Do you see directional blur with the glasses or contacts? Is it easily resolvable? I suspect at that level the directional blur is okay, and if it’s fine on your contacts, I doubt that is the problem. Have you had your glasses straightened professionally? Even if they look straight, there are all kinds of ways that they can be tweaked that will give someone headaches/make them feel sick. I’m assuming your differentials have no astigmatism, as well? Is there anything different about your glasses that you’re having problems with and your contacts that are doing fine?