What do O.S. and O.D. mean in my prescription?

[Noel]

What do O.S. and O.D. mean in my prescription?

[Ricky]

The OS is the short letter for "oculus sinister": (LEFT EYE) and OD is short for "oculus dexter" (RIGHT EYE )

[Ronan]

This characters often appear on prescription. Opticians use O.S to stands for left eyes and O.D to stands for right eyes. Besides, on your prescription, you may also see characters like D.V (distance vision), N.V(near vision) and PD (Pupillary Distance) etc.