Astigmatism and the Snellen

I recently got myself a test lens kit, but I’m finding it hard to dial in the exact CYL correction with just the Snellen alone. I have seen some videos of people using red and green light, what is that all about? What do I need besides the Snellen in order to set my CYL correction accurately?

try this image with one eye at time and find the exact distance that allows you to se a specifc line sharper than the others

the axis that appears sharper is the one that the cylinder axis must be matched. (notice if the vertical line is the sharpest one, so you axis must be 180º
astigmatism it’s a cornea’s aberration, so it’s more tricky to cure.
You shall not reduce your astigmatism prescription when in the Jake’s method.
i made a reduction and just ignore my astigmatism correction, which is 0,75 , because i had some doubts when choosing the parameters at the zenni optical website, so my glasses gives me a little bit of dizzyness when doing AF. So my next reduction i will make sure to put back the astigmatism prescription

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By next time make sure to check that cylinder first, since you may at that point need less of it.


Hi Jake,

I discovered something recently using my normalized glasses or without any lenses at all. I’ve recently been struggling with AF for the past 5-6 months, but I think my issue was with using text rather than something in nature. Also my issue could also be due to astigmatism, which I have under -1.

When looking at text I have tendency to read rather than look at each and every letter and observe its shape and so on. When looking at tree branches or telephone wires, for example I notice that my eyes are attempting to pick up small thin branches and eventually do. I was excited to have discovered this just 2 days ago. My joy may be premature, as I went immediately indoors to take centimeter measurements and found no improvements. Am I being too impatient? Should I expect centimeter improvements much later on after having found this?