How to Read an Eyeglass Prescription for Reading Glasses: OD, OS, Sphere, Cylinder & Axis Explained

If you’ve ever held a piece of paper with cryptic abbreviations like OD, OS, SPH, CYL, and AXIS, you’re not alone. Understanding how to read an eyeglass prescription is a key skill for anyone shopping for reading glasses, progressives, or blue light glasses. Whether you’re dealing with presbyopia, astigmatism, or just need a little help with close-up tasks, decoding your prescription ensures you get the correct lenses every time.

In this guide, we’ll break down each part of a typical reading glasses prescription, explain the difference between OD and OS, and show you how to use that information when choosing your next pair of stylish readers. Plus, we’ll highlight a few popular options from Peepers that can fit your needs—like the Rory (Blue Light) and the Le Fun Club (Blue Light).

What Is a Reading Glasses Prescription?

A reading glasses prescription is a written order from an eye doctor that specifies the lens power needed to correct near vision. Unlike a standard eyeglass prescription that might include distance vision correction, reading glasses prescriptions are primarily focused on the “add” power—the magnification required for comfortable reading or other close-up tasks.

Most reading glasses prescriptions include the following key components:

• OD and OS – Right and left eye abbreviations
• Sphere (SPH) – The main lens power for nearsightedness or farsightedness
• Cylinder (CYL) – Correction for astigmatism (if present)
• Axis – The orientation of the cylinder correction (0–180 degrees)
• Add – The additional magnification power for reading (common in progressives or bifocals)

If you have a prescription that only shows a single number like +1.50 or +2.50, that’s your reading magnification. But if you see more details, don’t worry—we’ll walk through it step by step.

Understanding OD and OS: Right Eye vs. Left Eye

One of the first things you’ll notice on any prescription is the letters OD and OS. These are Latin abbreviations:

• OD stands for oculus dexter (right eye)
• OS stands for oculus sinister (left eye)

Sometimes you might also see OU, which stands for oculus uterque (both eyes). Understanding which eye is which is crucial because your eyes may require different lens powers. For example, your right eye might need +1.50 while your left eye needs +2.00.

When you shop for reading glasses, you’ll often see options like +1.00, +1.50, +2.00, and so on. If your prescription is the same for both eyes, a standard pair of off-the-shelf readers works fine. But if your eyes have different strengths, you may need custom lenses or progressives.

Breaking Down the Numbers: Sphere, Cylinder, and Axis

Now let’s dive into the three most common numbers on a prescription: sphere, cylinder, and axis.

Sphere (SPH)

The sphere value indicates the amount of lens power needed to correct nearsightedness (negative sign, e.g., -1.00) or farsightedness (positive sign, e.g., +1.50). For reading glasses, most prescriptions will have a positive sphere value because they are designed for close-up work.

If your sphere is -2.00, you are nearsighted and may need a different type of lens for distance, but your reading glasses may still have an “add” power. For pure reading glasses, the sphere is often the same as the magnification strength.

Cylinder (CYL)

The cylinder value corrects astigmatism, an irregular curvature of the cornea or lens that causes blurred vision at all distances. If you have astigmatism, your prescription will include a cylinder number (e.g., -0.75 or +1.25) and an axis. If the cylinder field is blank or says “DS” (diopters sphere), you have no astigmatism correction.

For many people, cylinder correction is essential for clear vision. If you have astigmatism, standard off-the-shelf readers won’t work—you’ll need custom lenses or progressives like the Next Level (Progressives), which can incorporate both sphere and cylinder in one lens.

Axis

The axis is a number between 0 and 180 that describes the orientation of the cylinder correction. It tells the lens maker where to place the cylindrical power in the lens. For example, an axis of 90 means the correction is vertical, while 180 is horizontal.

Without the correct axis, the cylinder correction won’t align properly with your eye’s irregular shape, leading to blurry vision. So if you see an axis number on your prescription, it’s just as important as the sphere and cylinder values.

What About the “Add” Power?

For people who already wear distance glasses and need reading help, the “Add” power is the extra magnification for near vision. This is common in progressive lenses or bifocals. The add power is always a positive number (e.g., +1.50 or +2.25) and is added to the sphere value for the reading portion of the lens.

If you’re shopping for pure reading glasses (not progressives), you’ll typically only need the sphere value—which is essentially your add power. For example, if your prescription says +1.50 in the sphere column for both eyes, a pair of +1.50 reading glasses will work perfectly.

How to Choose the Right Reading Glasses Based on Your Prescription

Once you understand your prescription, selecting the right glasses becomes straightforward. Here’s a quick guide:

Prescription Component	What It Means	How to Choose Glasses
Sphere only (no CYL)	Simple farsightedness or presbyopia	Choose standard reading glasses with matching magnification
Sphere + Cylinder + Axis	Astigmatism present	Need custom lenses or progressives; standard readers won’t work
Different OD and OS	Unequal vision between eyes	Consider custom readers or progressives with separate lens powers
Add power listed	Bifocal or progressive needed	Choose progressives or bifocals (e.g., Next Level (Progressives))

If your prescription is simple (sphere only, same for both eyes), you have a huge selection of stylish reading glasses. For instance, the Birdie (Blue Light) offers a chic cat-eye shape with blue light protection—perfect for reading on screens. Or try the classic Goldie (Blue Light) for a timeless look that works with any outfit.

Common Mistakes When Reading a Prescription

Even after you know the basics, it’s easy to misinterpret certain details. Avoid these common pitfalls:

• Confusing SPH with ADD – Some prescriptions list SPH and ADD separately. The ADD is the magnification for reading, not the distance sphere.
• Ignoring Cylinder – If you have astigmatism, skipping cylinder correction can cause headaches and eye strain.
• Mixing up OD and OS – Always double-check which eye is which. A simple mistake can lead to wrong lenses.
• Assuming all + numbers are the same – +1.50 is not the same as +2.00. Use exactly the strength your doctor prescribed.

When to Consider Blue Light or Progressive Lenses

Reading glasses aren’t just for paper books anymore. Many people spend hours on digital devices, which emit blue light that can contribute to eye strain and disrupted sleep. That’s where blue light reading glasses come in—they combine magnification with a blue light filter to protect your eyes during screen time.

Peepers offers a wide range of blue light readers, like the Tiki (Blue Light), which features a fun, retro-inspired design, and the Center Stage (Blue Light), a bold geometric frame that makes a statement. Both provide clear vision while filtering out harmful blue light.

If you need different prescriptions for distance and near, progressives are your best bet. The Next Level (Progressives) offer a seamless transition from far to near without the line in bifocals. They’re ideal for people who want one pair of glasses for all activities.

Final Tips for Ordering Reading Glasses Online

Once you’ve decoded your prescription, ordering reading glasses online is easy. Here’s what to keep in mind:

• Check the return policy – Make sure you can exchange if the strength feels off.
• Measure your pupillary distance (PD) – This ensures the optical center of the lens aligns with your pupil.
• Look for UV protection – Even reading glasses should block 100% of UV rays if you wear them outdoors.
• Consider blue light filtering – If you read on screens, blue light lenses reduce strain and improve sleep.

With these tips, you’ll be confident in choosing the perfect pair of reading glasses for your needs.

Ready to find your next pair? Explore the stylish and functional Le Fun Club (Blue Light) from Peepers—a playful design that combines reading magnification with blue light protection, perfect for your daily screen time and leisure reading.