Centimetre Measurements and astigmatism

I’ve been recording my centimetre measurements for about 6 weeks now and I always found the left eye (with a worse astigmatism) harder to measure for blur. I sometimes found it hard to judge and would get very different readings which were worse than my right eye, even though from a diopter perspective it was .25 less than my right.

I’ve since tried measuring my astigmatism using jake’s ingenious tool. WOW! I could really see the astigmatism like never before as the arrow and dial markings would be straight and dark more or less exactly on the Axis as on my prescription (I really hate that definition now) from my optometrist.

However it led me to realise that my astigmatism could be what’s causing the inconsistency in my centimetres for my left eye. I was using a home made centimetre measuring tape and printed cars with text to assess my distance for blur but I think I’m getting better results using the astigmatism dial - if I have the arrow located on the correct axis for that eye of course.

I’m just wondering if anyone else with astigmatism has found that this is a better way for them to measure their centimetres and if my hypothesis is indeed correct!

For reference my astigmatism is :
Right eye - axis 165 Cyl -.0.75
Left eye - axis 120 Cyl -1.00


I also use the astigmatism dial to measure cm regularly.
I measure both spherical blur distance (second line blur horizon) and overall blur distance (SPH + CYL, first line blur horison)

I tried the astigmatism dial and found it to be accurate. My test lens kit confirmed the axis within about 2 degrees of what the dial indicated.

I measure my CM with the normal tape measure method, and find that my astigmatism plays a role in my results being more variable than they probably should be. I think the biggest reason why is because of lighting. In ideal lighting the astigmatic blur is very easy to overcome with active focus. Since I realize this is the case, I now also track the lighting level too (lux). Even though the data points can vary I am able to see an overall trend to indicate where my eyes are truly at. All and all the CM is just a reference to also compare to your everyday experience.

On a side note, I’ve tried to keep my neck and shoulders loose while working at my desk and I turn my whole head when looking at my computer screen. As a oppose to only moving my eyes with a tight neck. It seems to improve directional blur and make active focus much easier. Especially because both eyes are seeing the screen equally rather than from the corner of my eye, if that makes sense.


I’ve been stymied as to how I can accurately measure my right eye for where clarity and just-to-blur are. There is no clarity. I am thinking I’ll have to put Jake’s astigmatism dial on a thumb drive & have it printed in color. So far, this has been a stopper for me; looks like this will allow me to continue on in learning & understanding.