Astigmatism Prescription

by Mark

Q: How can I read this astigmatism prescription?

So I tried out new glasses, the first pair of my life, for about a week. Everything looked terrible; fine detail like text was clearer, but people looked like dwarfs and their faces looked like trapezoids.

Also, the left eye seemed to be magnified more than the right, making things seem like I couldn't quite focus on them correctly. When I took the glasses off, it took me a solid 30 mins to adjust, and my left eye almost felt cross-eyed. With my naked eyes, I swear that my eyes see exactly the same when I close one or the other.

I went back to the doctor and he gave me a spiel about how I was seeing the real world now with the new glasses, but I finally talked him down to 50% of the prescription, and he said he was previously giving my left eye 125% and my right eye 100%, which I said I was noticing and greatly disliked. My new prescription is as follows:

OD Pl -50 x125
OS Pl -50 x045

I have no idea what these numbers mean, especially the wildly diverging x125 and x045. Do those asymmetrical numbers have anything to do with how much "strength" each lens has, or something else?

A: I must say from the beginning that it is not easy to accommodate for astigmatism, especially if it is your first pair of glasses. Eye needs adjusting, and it happens slowly over time. Therefore, the first pair of glasses must have a lower diopter and it will grow to the next consultation.

If you get your first pair of glasses with maximum diopters, will happen what you described already above, namely you will not be able to get used to these glasses. It is best to start slowly and reach the final result in time.

To understand your astigmatism prescription, you should know that the astigmatism correction is made by the cylindrical lens. This is a particular lens that is not uniform over the entire surface and therefore must be placed in a certain position, in front of your eye.

This position is determined by the axis of the cylinder. Axis can be between 0 and 180 degrees.

First value on your prescription is the diopter (-0.50)

The second value is the axis (125 degrees or 45 degrees).

Generally, the axis varies barely in time, but diopters can grow. The strength as you said, is determined only by the diopter, the axis will indicate the position of the diopter in the lens.

Hope this helps,

Comments for Astigmatism Prescription

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Aug 22, 2014
Frame Adjustment
by: Sass

So by having read the description about how the cylindrical lenses work in this article (and other places on the internet), I assume that the adjustment of frame in front of the eye becomes a crucial factor as well, right?

My problem is, that I have astigmatism in my newer prescriptions (I am wearing glasses since I was 10 and had no such problems as follows in over 20 years). since getting my 2 new prescription, each having its own diopter, and making 6 (you read it right, 6!) pair of glasses out of these 2 prescription in less than 1 year; I still cannot use my glasses without feeling dizzy , eye-strained and head-ached.

When I try so adjust the frames with my own hand; the characteristics of such pains change; by that I mean when I play with the frame and bend it different ways, the pain in my eye changes as well but damn it does not go away! I keep bending the nose bridge to make the lenses make a V shape, make a - shape or make a ^ shape, keep twisting the bridge to have the curvature of the lenses aligned to my eyes', play with the temples trying to align the center of the lens with my puples, etc.

My problem is, that optometrists seem to not understand my problem either and don't really know/care how to fix the frame the way it should be.

The question is: how can I be sure that all the elements of the lenses (centers, cylindrical Axel, the curvature of the lens, the angel at which it sits in front of my eyes, the distance of the surface of the lens from my cornea, etc) are actually what they are supposed to be? How can optometrist measure such things and correct that?

Aug 24, 2014
by: Arpi

Well Sass,
For a monofocal eyeglass, all this characteristics are to consider, but not the most important.

Usually, the frames are manufactured in a way that respects this characteristics and tempering with them only makes the situation worst. Normally, the optometrist and the optician consider this characteristics when shaping the lens and adjust the position of the axis in the frame, not changing the shape of the frame-front itself.

As you describe the problem, I would say that the problem is the cylinder diopter. You said the cylinder is something new in your prescription, I guess is a small one like 0.50 or 0.75 , but if you are used to prescriptions without cylinder for so many years (the astigmatism part) is hard to change that, so I would suggest you to try a smaller cylinder diopter or no cylinder diopter at all if the vision difference is not too big and you will see that the dizzy part will go away.

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