Demystifying your Vision Prescription: Understanding the Numbers and Symbols
At some point in your life, you may have taken an eye exam and been given a prescription for corrective lenses. But have you ever looked at the numbers and symbols on your prescription and had no idea what they meant? This can be a common experience, especially for those who are new to wearing glasses or contacts. In this article, we will demystify the numbers and symbols on your vision prescription and help you better understand what they mean.
Understanding the Terminology
Before we dive into the numbers and symbols on your prescription, it’s important to understand some basic terminology. One term you may encounter is “visual acuity,” which refers to how well you can see at a distance. This is typically measured using a Snellen chart, which consists of rows of letters that get progressively smaller.
Another important term is “refraction,” which refers to the bending of light as it passes through your eye. The amount of refraction that takes place depends on the shape of your eye and the curvature of your cornea. If your eye doesn’t refract light properly, you may have a refractive error, such as nearsightedness, farsightedness, or astigmatism.
The Numbers on Your Prescription
Now let’s take a closer look at the numbers on your prescription. These numbers represent the amount of correction you need to see clearly. Here’s a breakdown of what each number means:
• Sphere (SPH): This number indicates the amount of nearsightedness or farsightedness you have. If this number is positive, you are farsighted. If it’s negative, you are nearsighted. The higher the number, the stronger your prescription.
• Cylinder (CYL): This number indicates the amount of astigmatism you have. Astigmatism occurs when your cornea is irregularly shaped, causing blurry or distorted vision. This number will be accompanied by an axis (see below).
• Axis: This number tells your eye doctor where to place the cylindrical correction on your lens.
• Addition (ADD): This number is used for bifocal or progressive lenses. It indicates the additional correction needed for reading or close-up work.
Decoding the Symbols
Along with the numbers on your prescription, you may also see some symbols. Here’s what they mean:
• OD: This stands for “oculus dexter,” which is Latin for “right eye.”
• OS: This stands for “oculus sinister,” which is Latin for “left eye.”
• OU: This stands for “oculus uterque,” which is Latin for “both eyes.”
Other symbols you may see include a plus sign (+), which indicates farsightedness, and a minus sign (-), which indicates nearsightedness.
Putting It All Together
Now that you understand the terminology, numbers, and symbols on your vision prescription, you can make more informed decisions about your eyewear. When selecting glasses or contacts, be sure to choose options that match your prescription exactly. Additionally, be sure to visit your eye doctor regularly to check for any changes in your vision.
In summary, understanding your vision prescription can be confusing at first, but with a little explanation, it doesn’t have to be. By breaking down the terminology, numbers, and symbols on your prescription, we hope to have helped you feel more empowered and informed about your eye health.
