Although roughly 3 out of every 4 people in America require corrective lenses, many people wonder how bad their eye prescription is – especially as the numbers and symbols are often difficult to interpret.
In this article, we look at how to read an eye prescription and what the numbers mean.
How to read an eye prescription
Positive numbers, such as +1.00, explain how strong a lens needs to be to correct for farsightedness. Farsightedness means a person can see distant things better than nearby objects.
Negative numbers, such as -1.00, indicate the lens strength needed to correct shortsightedness. Shortsightedness is when a person can see close things better than distant objects.
Other tips
The following tips can help people read their eye prescriptions:
- A large number: Whether a + or -, a large number indicates a stronger prescription.
- OS and OD: On an eyeglasses prescription, OS stands for Oculus Sinister, which refers to the left eye. OD stands for Oculus Dexter and refers to the right eye.
- Eye differences: It is common for people to have different qualities of vision in their left and right eyes, particularly those with astigmatism.
- Spherical correction (SPH): The spherical correction (SPH) refers to the lens strength needed to correct vision that affects the whole eye. This is usually the first number listed.
- Cylindrical correction (CYL): Cylindrical correction is the second number and is only on prescriptions for people with astigmatism.
- ADD: Some people need a different prescription to see things that are close by. ADD refers to the strength that the optician needs to add to a prescription to magnify objects.
- AXIS: The axis notation tells lens makers where they should place the astigmatism correction in a lens.
- PRISM: Eye doctors incorporate a prism into a lens to help correct problems with the eyes working together, such as one eye tilting inward while the other looks straight ahead.
A person with any questions about what their prescription means should speak to their optician who can answer any questions and help explain the numbers.
