Understanding Your Prescription: What Do All Those Numbers Mean?
Navigating the world of eyewear prescriptions can be as tricky as trying to read a book with the wrong glasses. When you get your prescription after an eye exam, you’re handed a piece of paper filled with numbers, signs, and terms that seem more like algebra than instructions for improving your vision. But fear not! We’re here to demystify those numbers and terms so you can understand exactly what they mean for your eyesight.
Sphere (SPH)
The “sphere” part of your prescription is indicated by a number which measures in diopters, the unit used to denote the power of the lens your eye requires to focus properly. This number can be positive (+) or negative (-). A positive number indicates farsightedness (hyperopia), meaning your eyes work harder to focus and generally causes more trouble with close up vision. A negative number denotes nearsightedness (myopia), where close objects are clear, but distance vision is blurred. Essentially, this value reflects the lens strength needed to correct your vision to standard vision (20/20 vision in the US or 6/6 vision in Europe).
Cylinder (CYL) and Axis
These two values go hand-in-hand and are crucial for those with astigmatism, a condition where the cornea or lens of the eye is irregularly shaped, causing blurred or distorted vision. The “cylinder” quantifies how much astigmatism you have in diopters, similar to the sphere. It suggests the amount of lens power needed to correct the astigmatism.
The “axis” specifies the orientation of the astigmatism in degrees (ranging from 0 to 180). It’s the direction in which the cylinder part of the lens should be placed to correct your vision properly.
Add
This term is primarily found in prescriptions for bifocal or multifocal lenses and stands for “addition.” This number, which also is measured in diopters, signifies the additional magnification power needed in the lower part of multifocal lenses to correct presbyopia, the age-related condition where the eye’s lens stiffens and loses the ability to focus on close objects. It essentially tells the lens maker how much power to add to the bottom portion of your multifocal lenses for near tasks such as reading.
Putting It All Together
Understanding your prescription is critical for ensuring you get the right glasses or contacts, facilitating not just clear vision but also comfort. If your prescription includes all these sections, it’s important to consider each one carefully when selecting your glasses. Always consult with your optometrist or ophthalmologist to clarify any uncertainties and ensure your eyewear is perfectly suited for your needs.
While it may initially seem daunting to decode your prescription, becoming familiar with these terms empowers you to make informed decisions about your eyewear, leading to better vision health.
For further reading and resources, visiting a reputable site such as the American Optometric Association can provide extensive insights into understanding eyewear prescriptions and eye health. Remember, your eyecare provider is your best resource for any questions or clarifications about your specific needs.
Now that you know the meaning behind the numbers and terms, you can approach your next eye exam with confidence! If you’re in need of an eye exam and current eyewear prescription, we have same day / next day appointments available!
