Understanding Your Eye Prescription

Understanding Your Eye Prescription

Understanding your eye prescription can be challenging. Here, at Bellevue Eye Specialists, we want to clarify any inquiries you have regarding your eye prescription. We want to make your glasses/contacts lens experience the best it can possibly be.

Sample Prescription:

  Sphere Cylinder Axis ADD VA
OS -1.00 -0.50 180 +2.00 20/20
OD -1.00 -0.50 180 +2.00 20/20

Where To Start

Your prescription is made of a few measurements that help our lab to create the right lens for you. Here is a brief explanation on what each one of those measurements mean:
  1. Sphere: The Length of Your Eyes

    • Myopia (-):The minus sign in front of the spherical number is how much minus power needed to help someone see 20/20 (or as close to that as possible). As a result of this, a myopic person can see clearly near them, but cannot see well at a distance.
    • Hyperopia (+): The plus sign in front of the number is how much minus power is needed to help someone see 20/20 (or as close to that as possible). As a result of this, a hyperopic person can see clearly at a distance, but might have trouble seeing at near distances.

2. Cylinder: The Shape of Your Eyes

Our eyes are born evenly spherical in all directions. Sometimes over time, due to genetic reasons or other medical reasons, our eyes can change in shape. This is a common and known as astigmatism. Typically with astigmatism, our eyes turn from being an even spherical shape to an oval “football” shaped eyeball. Astigmatism can be easily corrected through proper corrective vision.

3. Axis: The Direction the Corrective Power Is Adjusted To

The axis measurement is the direction that the corrective vision power is adjusted to.

4. ADD: Optional Reading Power

The ADD power determines if you need a pair of single vision or progressive/bifocals. As we age, it is common for many people to have trouble with reading up close. Around age 40, most people will start to need reading glasses. Ask your doctor if you have any questions regarding using a pair of bifocals/progressives.


These are some basic explanations on how your eye prescription works. Eye prescriptions are catered to a specific individual and should be updated every 1-2 years with an optometrist. If you have any questions, please feel free to schedule an appointment with one of our experienced doctors. If you need any glasses adjustments, we are more than willing to help you adjust your glasses properly. Call us today to schedule an appointment!
Cited Sources:
Boyd, K., & Edmond, J. (2018, September 07). What Is Astigmatism? Retrieved June 27, 2020, from https://www.aao.org/eye-health/diseases/what-is-astigmatism
Boyd, K., & Satterfield, D., MD. (2018, April 04). Farsightedness: What Is Hyperopia? Retrieved June 27, 2020, from https://www.aao.org/eye-health/diseases/hyperopia-farsightedness
Tubert, D., & Pagan-Duran, B., MD. (2020, May 15). Nearsightedness: What Is Myopia? Retrieved June 27, 2020, from https://www.aao.org/eye-health/diseases/myopia-nearsightedness

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