Differentials for High Astigmatism Low Myopia

Guys I have read many articles on Endmyopia for months now, but I am still facing some doubts. My first diffs were a disaster because the sph in both eyes was 0.5 D lower than my norms whereas cyl was same in diffs and norms (only 0.5 D lower power is not good enough for diffs and keeping full distance power even in diffs is useless). So, I haven’t found anything definitive to help me choose correct differentials for high astigmatism (-2.25D in left which is more than the sph I have in the same eye i.e. -2D) and that’s why I am asking, not that I am too lazy to read, but I have genuinely read and genuinely need some good opinions.

I have made some calculations and decided that having 1 D lower for both sph and cyl in diffs is sufficient (as I view screens and books from about 100 cm distance).

Do you, based on your reading experience on endmyopia, think this is a good idea? I am not begging for any diopter specific advices here because I know it’s not allowed. We are having a chat here, and I want to know your opinion.

Mentioning my current glasses correction (norms) just in case it is of any use

Right Eye
Sph -1.75, Cyl -1.50, Axis 180°

Left Eye
Sph -2.00, Cyl -2.25, Axis 170°

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Don’t worry, nobody will take you for a Plzbro. :smile: This is a genuinely tricky situation and there seems to be little on the forum that addresses it. Even @kem who had a similar situation, went through a lot of trial and error before figuring it out. I can’t help you, as I have higher spherical than cylinder needs, but as I do have astigmatism, I would like to see a better organised (and more concentrated) resource on astigmatism on the forum, in the form of a rough guide, with a section dedicated to the low sphere high cylinder situation… @Salt has made a start on this, @Bianca had made a contribution, I would be willing to help, but there has as yet been no practical initiative to get this going as an organised group project. We need an astigmatism specific @Laurens to get this going.

Good luck with this, and I hope you get some feedback from others in your situation.

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So, ideally for ppl with less astigmatism, is it that same amount of diopters is generally decreased for diffs? For instance, if a person has -3D sph nd -2D cyl for left eye and -4D sph nd -3D cyl for right eye and he views at 100 cm dist. for close-up, then do the diffs ideally become Left: -2D sph nd -1D cyl and Right: -3D sph nd -2D cyl in such a case?

Again, not asking for an advice here, but an opinion/observation on a general case.

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Haven’t yet come across a good formulaic approach to astigmatism and I’m not so sure one exists. Some individuals are sensitive to changes in cyl, others not at all. Some have success replacing cyl with added sph, others not so much. Some succeed in ditching it entirely, though from memory this is more common when the axes are roughly perpendicular.

At the start, my cyl was -2.00/-2.50 and first diffs had a high cyl/sph ratio. The experience was pretty awful.

You might save yourself tons of trial and error by purchasing a test lens kit. A little more expensive up front, but might save you $ in the long-term and get you on a good glide path sooner.

Best of luck.

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@Astigmatism_Assasin

How could I have forgotten to add you to the list of people with high astigmatism? An excellent and concise response. I am itching to get a rough guide to astigmatism started, but don’t want to step on anyone’s toes. We may not end up with a formulaic approach, but at least save people a lot of searching. I think the first bit of advice for this particular situation would be, as you suggest, get a test lens kit.

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Sometimes being forgotten bodes well :slight_smile:

To my knowledge nobody has taken on this chore and I doubt anyone would object to your doing so. I would happily contribute in any way possible.

@Salt has made a start on it, and I would hate to take it out of her hands unless she is happy for me to do so.

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I understand you’ve been wearing the high cyl for quite a long time now, which means your eyes and brain are used to being corrected on the astigmatism.
Considering this, the 1D drop from everything (both SPH and CYL in both eyes) for differential is slightly aggressive. But not impossible.
You can definitely try and if the blur / double vision challenge is too much you may consider stepping back to a slightly bit more correction, or temporarily move closer to the monitor and books (e.g. to 60cms) and start increasing the distance from there back to 100cms.
I’d definitely suggest observing the lights in your study / work set up, and during the leisure time screen use. High astigmatism is often a sign of receiving the lights from 1 certain direction at the desk (or watching films on smart phone or tablets while laying on one side on the sofa or in bed, etc)
Good luck on improving your eyesight and reducing the complexity. :slightly_smiling_face:

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