Difference between revisions of Guide:Reading glasses prescriptions
m clarify that cylinder is in addition to the spherical, rather than an absolute value to replace it. (I think). And "right" -> "correct" just because right often means not-left on here. |
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[[Spherical]] is your overall myopia, in all directions. | [[Spherical]] is your overall myopia, in all directions. | ||
==Cylinder== | ==Cylinder== | ||
[[Cylinder]] is myopia in a specific direction of your eye. Think of a straight line going across the surface of your eye at a certain degree. The degree this happens at is your axis. | [[Cylinder]] is the additional myopia in a specific direction of your eye. Think of a straight line going across the surface of your eye at a certain degree. The degree this happens at is your axis. | ||
Cylinder correction means your eye has some level of [[astigmatism]]. | Cylinder correction means your eye has some level of [[astigmatism]]. | ||
==Axis== | ==Axis== | ||
[[Axis]] is the degree at which cylinder values are relevant. The | [[Axis]] is the degree at which cylinder values are relevant. The correct cylinder value but the wrong axis value would make the correction pretty worthless! When reducing your correction, you should never ever change the axis, especially if you've had that value of axis for a long time. | ||
If you don't have any cylinder correction, you will not have an axis value either. | If you don't have any cylinder correction, you will not have an axis value either. | ||
==Prism== | ==Prism== | ||