Everything You Need to Know About Reading Your Eye Doctor Prescription
Have you ever glanced at your optometrist's prescription after your pupils finally finish dilating and wondered what all those numbers actually mean? It looks like a secret code but it’s actually quite simple once you break down the abbreviations and columns. Getting the right information ensures your new frames provide the best possible vision for your lifestyle.
Here is how you can read your own prescription before you order your next pair of glasses.
Common Abbreviations on Your Prescription
When you look at your paper from the eye doctor, you’ll see a few standard abbreviations. These tell the lab exactly how to craft your lenses.
OD (Oculus Dexter): This is Latin for right eye. All the numbers in this row apply to your right side.
OS (Oculus Sinister): This is Latin for left eye. This row applies to your left side.
OU (Oculus Uterque): This means both eyes. If you see this, that measurement applies to both sides.
It’s incredibly common to have different numbers for your OD and OS rows. Even though your eyes may look symmetrical from the outside, your internal vision needs can be quite different. Your eyes are two distinct organs, and they often develop nearsightedness, farsightedness, or astigmatism at different rates. One eye may be slightly longer or have a more curved cornea than the other, leading to a unique prescription for each side.
If you notice your right and left eye numbers vary, don’t worry. Very few people have perfectly identical vision in both eyes. Whether you have mild nearsightedness in one eye and a stronger astigmatism in the other, our lab uses these exact, asymmetrical measurements to balance your vision, reduce eye strain, and ensure you have comfortable, accurate sight through both lenses.
Main Columns You Should Know
Most prescriptions are laid out in a grid. While every doctor uses a slightly different form, these are the three most common columns you’ll encounter when ordering glasses online.
SPH (Sphere): This is the primary power of your lens. It corrects for common vision issues like nearsightedness (myopia) or farsightedness (hyperopia). If you see a minus sign (-), you’re nearsighted; a plus sign (+) means you’re farsighted. The further the number is from zero, the stronger your prescription.
CYL (Cylinder): This column indicates the amount of lens power needed to correct astigmatism, which is a common condition that causes blurry or distorted vision at all distances. If this section is blank, is marked with a zero, or says "DS" or "SPH," it means you don't have astigmatism.
AXIS: This number only applies if you have a cylinder value listed. It’s a number between 1 and 180 that tells the lens lab the exact angle or orientation for your astigmatism correction. Without the right axis, your vision through those lenses may feel slightly off or distorted.
Depending on your specific vision needs, your doctor might include a few extra details to ensure your glasses are comfortable.
ADD (Addition) This is extra magnifying power used for the bottom part of bifocal or progressive lenses. It helps with reading or close work.
PRISM You’ll rarely see this. It’s used if your eyes need help working together to prevent double vision.
PD (Pupillary Distance) This is the distance in millimeters between the centers of your pupils. It’s crucial for aligning the lens correctly in the frame. Your doctor might not write this on your medical prescription, but you must have it to order glasses online.
Understanding Your Lens Power
The numbers on your prescription are measured in diopters. The further away from zero the number is, the stronger the vision correction you need. A number like -0.50 is a light prescription, while a number like -5.00 is a much stronger one.
When you're using your prescription to order glasses online, the most important thing is to copy the numbers exactly as they appear on your document. If you’re ever confused about what a number means, you can always call your optometrist's office to double check.
Ready to Order Your New Pair?
At NURILENS, we make getting your prescription right easy when you buy your glasses online. You don’t have to manually type in every single digit. Simply take a clear photo of your prescription or submit a scan during checkout to buy your favorite pair of handcrafted frames.
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