Understanding Your Prescription

A prescription for will generally contain the powers for the lenses needed by each eye and the lens power is written in diopters.

OD (oculus dextrum) stands for "right eye" and OS (oculus sinistrum) for the "left eye".

The "Sphere" indicates how nearsighted or farsighted you are. A plus (+) power indicates farsightedness and a minus (-) power indicates nearsightedness.

"Cylinder" refers to the measurable degree of astigmatism of your central cornea.