Your Eye Glass Prescription: The Meaning of OD and OS
Edmonton Eye Doctors

06-06-2025

Your Eyeglass Prescription

When you receive a prescription for eyeglasses, you might notice abbreviations like OD, OS, and sometimes OU. These terms can seem confusing at first, but they’re essential for ensuring your prescription glasses are tailored accurately for each eye.

What Do OD and OS Stand For?

OD = Right | OS = Left

OD (oculus dextrus): This refers to the right eye.
OS (oculus sinister): This refers to the left eye.
OU (oculus uterque): Occasionally used to refer to both eyes.

These Latin terms are standard in the field of optometry and ophthalmology and are used on prescriptions to ensure clarity when describing the corrective needs of each individual eye. An optometrist in Edmonton, or anywhere else, uses these terms to guide optical labs in creating lenses with the correct prescription power, axis, and other important measurements.

More Than Just A Prescription: Why Accurate Measurements Matter

Thinking about ordering your glasses online? You might want to reconsider. While your prescription includes the essential details for lens power and correction, it does not include all the measurements required to make properly fitting prescription glasses. Your optometrist in Edmonton will take several additional measurements during your visit, including:

Pupillary Distance (PD): The distance between your pupils, necessary for proper lens alignment.
Optical Center Alignment: Ensures the clearest vision by aligning the thickest or thinnest part of the lens with your line of sight. Misalignment can cause eye strain or headaches.
Segment Height or Fitting Height: Especially important for progressive or bifocal lenses.
Vertex: The distance between the front of your eye and the back surface of the lens. This is especially vital for patients with high prescriptions, as even small variations in vertex distance can significantly affect visual clarity.
Pantoscopic Tilt, Frame Fit, and Wrap Angle: These subtle details influence visual clarity and lens performance.

Online retailers rarely, if ever, capture these critical measurements, which means your new glasses could be off just enough to cause eyestrain, headaches, or poor vision. At Eye-deology Vision Care in Edmonton, our trained opticians and experienced optometrists use advanced tools and expertise to ensure your eyewear is not just stylish, but perfectly crafted for your vision needs. Want to learn more about the shortcomings of purchasing eyeglasses online? Read Reasons Why You Should Never Buy Prescription Glasses Online

Choose Local, Choose Precision

Getting your prescription glasses from a trusted Edmonton optometrist means more than just a pair of glasses—it means peace of mind, expert care, and customized solutions for your vision. At Eye-deology Vision Care, we combine advanced diagnostic technology with a wide selection of designer frames and premium lenses to ensure you receive the best glasses in Edmonton.