View source for Guide:Reading glasses prescriptions


How do you read these complicated things!? Believe it or not, they're actually pretty simple to understand. First things first, remember myopia is not a medical condition, it is a refractive error. Therefore, your "prescription" is much more accurately referred to as vision [[correction]]. OD is oculus dextrus, or Latin for right eye. OS is oculus sinister, or Latin for left eye. 

==Spherical==
{{main|Spherical}}
Spherical is the overall correction, in all directions. It is measured in [[diopters]]. A minus value means the lense is used correct [[myopia]] and a plus value means it is used to correct [[presbyopia]] and/or [[hyperopia]].

==Cylinder==
{{main|Cylinder}}
Cylinder is the additional correction in a specific direction of your eye. It is measured in [[diopters]]. 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]].

Since cylinder correction is in addition to spherical correction, what the cylinder correction does depends on the spherical correction:
{| class="wikitable"
|+ Effect of including cylinder correction
! !! Minus Sphere !! Plus Sphere
|-
! Minus Cyl
| Increases myopia correction || Decreases presbyopia correction
|-
! Plus Cyl
| Decreases myopia correction || Increases presbyopia correction
|}

[https://www.youtube.com/watch?v=0AyE1BmKUh8 Explanation of positive vs. negative cyl correction]

==Axis==
{{main|Axis}}
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.

==Prism==
{{main|Prism}}
Prism is very rare on a prescription. It is effectively is an imbalance between how your two eyes see. It has been described as permanent [[double vision]].

==Pupillary Distance==
{{main|Pupillary Distance}}
Pupillary Distance or PD, is the final set of numbers you need to be aware of. Most likely this is not listed on your "prescription" you will need to ask for it or measure it yourself.

[[Category:Guides]]