When you look at your prescription for eyeglasses, you will see numbers listed under the headings of OS and OD. They are Latin abbreviations: OS (oculus sinister) means the left eye and OD (oculus dextrus) means the right eye.

Why is left eye OD?

These are simply abbreviations for Latin terms: OD is an abbreviation for “oculus dexter” which is Latin for “right eye.” OS is an abbreviation for “oculus sinister” which is Latin for “left eye.”

Which eye means OD?

O.D.- This is oculus dexter, meaning right eye. O.S.- This is oculus sinister, meaning left eye. O.U.- This is oculus uterque, meaning both eyes. Along the top, you might see different verbiage that generally has to do with measurements related to different aspects of your vision.