OD and OS are eye prescription abbreviations: OD means the right eye and OS means the left eye. They come from Latin terms used in optometry and ophthalmology, and you may also see OU , which means both eyes.

What they mean

  • OD = right eye.
  • OS = left eye.
  • OU = both eyes.

Why it matters

These labels show which eye a measurement or lens correction applies to, so the prescription is read correctly. Some clinics may use RE and LE instead, but OD and OS are still common.

Quick example

If a prescription says OD -2.00 and OS -1.50 , the right eye needs a stronger nearsightedness correction than the left eye.

Tiny tip

If you’re reading a glasses prescription, OD and OS are just the eye labels, while numbers like SPH, CYL, and AXIS describe the actual correction.