Noob Question on Astigmatism

Hi, I have had the same prescription -1.5 sphere both eyes for about eight years and went to the optometrist to get a test after sudden onset of floaters. Not knowing much she convinced me to immediately change to -0.5 sphere -0.5 cyl. left, and 0 sphere -1.0 cyl right. Somehow I tolerated wearing these for 2 weeks despite seeing worse than with no glasses in low light. I will say in the right lighting my brain seemed to force it to work out alright. I have no idea how she got to that prescription, but went to a new optometrist who came up with -1.0 sphere -0.25 cyl. left, and -0.75 sphere -0.5 cyl after .

My first question is should I even trust the results of this second exam given how drastically off I believe the first change was? Second is, if I did not have any major issues with the simple -1.5 both eyes, should I really start messing around adding astigmatism corrections and different sphere in both eyes (even if it can mean a larger reduction in sphere correction)? It seems I should have simply been given something like -1.25 sphere both eyes as a start.


It was discussed in one of the threads here that even optometrists give off different results. If possible, could you go to another optometrist and check?

Here in EM, it is best to put faith in yourself by learning how to assess your vision yourself as there are tests here. Along with that, you should feel it so that the prescription glasses given to you by the optometrists are comfortable and does not require effort to see. IMO, I also do not believe in the first change based on what you said:

You might have been prescribed far from what your eyes actually are and your have been letting your visual cortex adjust to it. If it feels straining, might as well as use your first ever prescription glasses. Could you give us your experience on the last exam? Does is feel right, clear and does not need some effort to see well?

Your astigmatism is low and, at best, can be ignored. However, that should also depend on your sensitivtity to it as some can make a huge drop in astigmatism without having trouble, while some are sensitive to a 0.25D drop in their cylinder. I was prescribed with -0.5D cylinders on both eyes but thankfully the shop I went to converts cylinder to their equivalent axial power. I am not sensitive to it as well, so it’s all good.

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I wouldn’t want to start putting cylinder correction in unless it makes a big and obvious improvement in your vision.

That sounds more reasonable to me, but you’ll have to try different things to figure out what works best for you. As a personal preference I’d try to keep the correction in front of both eyes the same (given that that’s what you’re used to and they’re so close) and not put in astigmatism correction unless you really need it. I was happy using -0.25 cyl in each eyes for a couple of months until I got rid of the astigmatism altogether (the optometrist initially recommended -0.75 and -0.5 cyl in each eye which I couldn’t tolerate at all.)

Totally agree. As you test yourself you’ll find that your eyes vary from hour to hour and day to day. The optometrist sees you at one moment in time and prescribes based on that “snapshot” of how your eyes were right then. As you test yourself you get a much better picture of what’s really going on with your eyesight.


This second measurement can be converted to -1D sph only in both eyes.
(-1.0 sph and -0.25cyl => sph kept and tiny cyl disregarded; -0.75D sph and -0.5 cyl => the cyl dropped and half of it added back to sph which is an official opto conversion, not an EM one).
So the second opinion reads as your full opto correction could be -1D in both eyes without cyl. So interestingly the opto (actually both optos) are suggesting lower corrections for you than what you are actually wearing. Corrections between -0.5D and -1D.
You must be one of those people - like me - who enjoys eagle eyes, i.e. some overcorrections for super sharp clarity.

If you like a bit more sharpness, that’s OK. Just keep it equal and sph only.
I guess by now you are not wearing any glasses in front of screens (maybe only for TV and subtitles). Most probably you don’t need to wear glasses when at home either. For the outdoors time, you can choose to enjoy sharp vision at distance and alternate it with zero corrections days (when it is safe to do, of course).

And though you don’t need cyl, you will want to make sure you are using your eyes with the same range of motion both horizontally and vertically.
If the cyl was measured around 90 degrees (between 75 and 105) you may have a tendency not to raise your eyes to look at the distance (or you may be looking left and right with your eyes only a lot, e.g. multiple monitors side by side).
If the cyl was measured around 180 = 0 degrees (between 165 and 15), you may have a tendency to turn with your head, too, when looking left and right (or you may have a regular activity that requires more looking up and down)
If the cyl measurements were completely different for the optos then you can just have a laugh at them and their results. You can still observe your vision habits though, that never hurt anyone. :wink:


Thanks all for the feedback. Unfortunately, I forgot to mention I have started wearing the second prescription already. It does seem to help with clarity at distance but feels unnecessary and does not improve close range significantly. Noticeablely worse in low light also with star bursts. Not to mention it has given a migraine and feeling of eye stiffness. I am a bit worried now that I have started adjusting to the astigmatism though I won’t be able to drop it.

Stop wearing those glasses before your brain gets used to them. (Accommodation works both ways).
Go back to equal sph no cyl ones.


Great comments above so I don’t really need to add much there.

Favorite part of all this, is the very good questions. Glad that we’re able to add enough resources to give you a basis to question the fairly drastic changes that were pushed on you.

In the future, good idea to not make actual focal plane changes till you feel confident that you understand and agree with the rationale behind them.


I wish I had asked the questions sooner and known there was a forum like this to get feedback. I probably could’ve ditched glasses by now too, I have stuck with the same prescription forever because in previous exams they would push something I didn’t understand and couldn’t adjust to.

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Thanks, yes I am very visual and addicted to seeing everything in detail. For this reason I am kind of shocked my myopia has improved considering I would almost always wear the glasses, maybe this is what was causing astigmatism though. I will stop wearing them in situations where they are unnecessary. My vision without them seems to be improving rapidly, but now the astigmatism in the right eye is considerably more noticeable (not sure if it is just lens induced, or was just present and was overcorrected on sph for so long it wasn’t noticeable). I switched to simple -1.0sph both eyes (bit of nausea and the lack of cyl correction on right eye is noticeable but feel I may actually be able to try stepping down to -.75 or even -.5. Not sure what would be best to help the astigmatism improve. Last optometrist re-check gave -0.75 sph -0.25 cyl. left, and -0.5 sph -0.5 cyl.

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