Understanding OS and OD in Optometry

Understanding OS and OD in Optometry

Photo by Ksenia Chernaya

If you’ve ever looked at a prescription for glasses or contact lenses, you might have been puzzled by the terms OS and OD. These abbreviations are actually Latin terms and are part of the language of optometry. In this post, we will demystify these common acronyms and explain their significance in your vision correction journey.

Decoding the Acronyms

OD stands for “oculus dexter,” which translates to right eye, while OS signifies “oculus sinister,” or left eye. These abbreviations help your eye care provider indicate which eye a particular prescription is for, ensuring accurate vision correction. These terms are a crucial part of your glasses or contact lens prescription, and understanding them can provide valuable insight into your eye health and correction needs.

Reading Your Prescription

Understanding OS and OD in Optometry

Photo by Ksenia Chernaya

Your prescription will typically list several values under each of these terms. These values include:

  • Sphere (SPH): This indicates the amount of lens power, measured in diopters, needed to correct nearsightedness or farsightedness.
  • Cylinder (CYL): This value corrects astigmatism and shows how much lens power is needed to correct the distorted vision caused by the irregularly shaped cornea or lens.
  • Axis: This is a number, in degrees, that works in conjunction with the CYL value to indicate the orientation of the astigmatism.

Understanding these values can help you make informed decisions about your vision correction options, whether that’s progressive lenses or classic frames.

The Importance of Regular Eye Examinations

Regular eye examinations are crucial for maintaining good eye health. Not only do they provide an updated prescription for your vision correction needs, but they also allow your eye care provider to detect early signs of eye diseases such as glaucoma or macular degeneration. Armed with the knowledge of what OD and OS mean, you can actively participate in your eye care and understand more about your vision prescription.

Avatar of Dr. Steven Liem

Dr. Steven Liem

Dr. Steven Liem, O.D., F.A.A.O. is an optometrist based in Pasadena, California. After obtaining his doctorate from UC Berkeley’s School of Optometry, he completed his residency in Pediatrics, Vision Therapy & Rehabilitation and became a Fellow of the American Academy of Optometry. When he isn’t busy streaming or making Youtube videos about video games, Dr. Liem aims to broaden accessibility to vision health through his involvement in optometric industry and tech.