How do I read an Rx prescription?

How to Read Your Eyeglass Prescription

Understanding your Rx prescription doesn’t have to be confusing. Most prescriptions follow a standard format, and reading them is easier once you know what to look for. Start from left to right, with separate columns for each eye—usually marked "OD" (right eye) and "OS" (left eye).

The Sphere value is often the first number you’ll see. In the example here, it’s -5.50. This negative number indicates nearsightedness, meaning the person sees nearby objects clearly but struggles with distance. The farther the number is from zero—whether negative or positive—the stronger the correction needed. A plus (+) value, on the other hand, would indicate farsightedness, where distant objects are clearer than close ones.

For instance, a prescription with -5.50 diopters means a moderate to high degree of nearsightedness. People with such prescriptions typically rely on glasses or contacts to see clearly at a distance. While this example only mentions Sphere, many prescriptions also include Cylinder and Axis values if astigmatism is present, which corrects for irregularly shaped corneas.

Don’t be thrown off by the medical jargon or abbreviations. Once you recognize that negative numbers mean nearsightedness and positive numbers mean farsightedness, you’re already halfway there. Your eye doctor can walk you through any additional details, but knowing the basics helps you understand your vision needs better.

Remember, every prescription is personal—what works for someone else may not apply to you. Always follow your optometrist's guidance when ordering lenses.