What Is My Vision Based on My Prescription


What Is My Vision Based on My Prescription?

If you wear glasses or contact lenses, you are likely familiar with your prescription. But have you ever wondered what it actually means? Your prescription is a set of numbers and abbreviations that determine the specific correction needed to improve your vision. Understanding your prescription can give you insights into your visual acuity and help you make informed decisions about your eye care. In this article, we will delve into the details of what your vision is based on your prescription.

Understanding the Terminology:

Before we dive into the specifics, let’s familiarize ourselves with some common terms you may find in your prescription:

1. OD and OS: OD stands for “oculus dexter” which means the right eye in Latin, while OS stands for “oculus sinister” which means the left eye.
2. Sphere (SPH): This indicates the amount of nearsightedness (-) or farsightedness (+) correction necessary to focus light properly on the retina.
3. Cylinder (CYL): This shows the amount of astigmatism correction needed. Astigmatism occurs when the cornea is irregularly shaped, causing blurred or distorted vision.
4. Axis: This number indicates the orientation of the astigmatism correction needed, measured in degrees from 1 to 180.
5. Add: If you have a bifocal or progressive lens prescription, this number specifies the additional correction needed for near vision.

Determining Your Visual Acuity:

Your prescription is a reflection of the visual acuity in each eye. Visual acuity is measured using a Snellen chart and is represented as a fraction. The top number in the fraction is the distance at which you are tested (usually 20 feet), and the bottom number represents the distance at which a person with normal vision can read the same line.

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For example, if your visual acuity is 20/40, it means you can see at 20 feet what a person with normal vision can see at 40 feet. If your visual acuity is 20/20, you have normal vision.


1. Can I use my prescription to determine if I need glasses?
Yes, if your prescription indicates nearsightedness, farsightedness, or astigmatism, it likely means you would benefit from glasses or contact lenses.

2. Can my prescription change over time?
Yes, your prescription can change due to various factors such as age, eye health, or medical conditions. It is important to have regular eye exams to monitor any changes.

3. Can my prescription be different for each eye?
Yes, it is common for people to have different prescriptions for each eye, especially if they have astigmatism or other refractive errors.

4. Can I get LASIK surgery to correct my vision instead of wearing glasses?
LASIK surgery can be an option for some individuals, but it is not suitable for everyone. Consult with an eye care professional to determine if you are a candidate.

5. What does it mean if my prescription includes an “ADD” number?
An “ADD” number indicates a bifocal or progressive lens prescription, which provides additional correction for near vision.

6. Can I use someone else’s glasses if their prescription is similar to mine?
It is not recommended to use someone else’s glasses as each prescription is customized to an individual’s specific needs.

7. Can I wear contact lenses with my prescription?
Yes, contact lenses can be prescribed for most vision conditions. However, it is essential to consult with an eye care professional for a proper fitting and guidance.

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8. Can wearing glasses with the wrong prescription harm my eyes?
Wearing glasses with the wrong prescription may cause discomfort, eye strain, and headaches, but it is unlikely to cause long-term harm. However, it is best to wear the correct prescription for optimal vision.

9. Can I purchase glasses or contact lenses online with my prescription?
Yes, many reputable online retailers offer prescription eyewear. However, it is crucial to provide accurate measurements and consult with an eye care professional if you have any concerns.

10. How often should I update my prescription?
It is generally recommended to have an eye exam and update your prescription every one to two years. However, certain circumstances may require more frequent visits, such as changes in vision or health conditions.

11. Can I improve my vision without glasses or contacts?
While glasses and contacts are the most common methods of vision correction, some individuals may benefit from vision therapy or other treatments. Consult with an eye care professional to explore your options.

Understanding your prescription empowers you to take charge of your eye health. By conducting regular eye exams, following your prescription, and seeking professional guidance, you can maintain clear and healthy vision. Remember, your eyes are unique, and only an eye care professional can provide personalized advice for your specific needs.