Differentials, astigmatism and active focus observation

I’ve been playing around with these ideas for about a year and a half. Lately I’ve been a bit frustrated because (whiney voice)… I’m not improving! Prescription complexity is a bitch. I started in the neighborhood of -2.5 SPH, but had multi diopter astigmatism (-1.5 R, -2.5 L). Anyway, my first set of differentials I did not reduce the CYL at all. Then for fun, I bought a set of differentials with no CYL correction. I had a lot of trouble with feeling or noticing active focus with my first set of differentials. However with these new differentials, I notice huge shifts in blurry to clear, after I blink or depending on how I stare or look at edges, or relax my focus. It’s like I can exercise more control of my focus, though I can’t hold it for long periods and don’t have a lot of control yet.

I’m starting to think that my astigmatism correction was really screwing up my ability to practice active focus up close. I’ve been afraid to drop the CYL entirely because of the recommendations in here to move slowly, but I’m starting to wonder if my lack of improvement lately has anything to do with this horribly complex prescription and my relatively high CYL to SPH ratio.

Anyway, just thought I’d share my experience. There are some days I just get so tired of f#cking blur challenge that I just want to give up. Other times I notice improvement and am motivated to keep trying. Maybe reducing the CYL portion of this prescription in stages will start me back on the road to improvement.


Had a similar experience (high cyl/sph). Reduced sph only in the first diffs and they were awful. Ditched cyl altogether in diffs and norms and it made all the difference in the world.

Also discovered when doing my own cm measurements that cyl was way over-prescribed, by a factor of x2. Have you found the same in your measurements?


I’m not sure about using cm measurements to determine if I’m over-prescribed in cyl. I honestly don’t measure often. I do know when I look at the circle line charts uncorrected, the lines on my axis (90 degrees from my axis?) are darker and clearer. Corrected, all lines look the same. So I have astigmatism, I’m just not sure how much it prevents me from seeing clearly.

1 Like

Very interesting, these are exactly my concerns (which I explained in this other topic). I have only reduced SPH so far and haven’t noticed much improvement from cm measurements.

I considered dropping CYL for differentials but I’m afraid to do so for the same reasons as you, so I asked if anyone had a similar experience. Now I’m reading this and it’s really helpful as my CYL numbers are similar to yours, I might give it a try! And regarding normalized, did you also reduce CYL in those or kept it the same? Also, I suppose you kept the original non-reduced SPH in the differentials just with no CYL, right?

1 Like

No, I had to increase the sph correction by about the amount Jake recommends (1/2 diopter for every diopter of cyl to be able to read my computer monitor. It feels weird to wear them and it seems like more work to focus, But I see wider results in clarity with my focus work. It might be worth a $16 pair of zenni glasses to try a normalized at something like -3.5 or so with no sph and see what that feels like.


I see. But even if it’s harder, it doesn’t create any noticeable kind of bad discomfort (headaches, etc…), correct? Please do keep up us updated :slight_smile:

Even I bought my first diffs and did not do any cylindrical reduction. But that was not a good idea asI got to know from a person (whose name I will not mention) in the forum that I should’ve reduced astigmatism too and that I should not use them.

Current norms
RE: -2 D sph with -2.25 D cyl
LE: -1. 75 D sph with -1. 5 D

-0.5 sph reduced from each eye for diffs.

Mum won’t buy me another pair for at least one more year. Please suggest to me what should I do!

1 Like

That’s a tough one and I’m not sure what to tell you. Is it an issue of cost for your mom?

It’s hard to experiment on yourself when you don’t have access to any tools. You could try going lens-free for near work, bringing your work close enough to provide a little blur challenge, and see how it feels. Other than that you’re going to have to get mom on board with your project.

1 Like

Ya well aparently, wearingthose glasses I am still getting hyperopic defocus for astigmatism. Nd bringing my work close enough would mean keeping it at about half foot from my face. :man_facepalming: