You just got your eyes tested. The doctor hands you a slip with numbers, abbreviations, and two columns — and walks away. Sound familiar? Most people have no idea what their prescription actually means. With over 50 years of optical expertise, we've helped thousands of customers decode that little slip of paper. Here's everything you need to know in under 2 minutes.
A Quick Real-World Example
Here is what a typical prescription looks like:
| SPH | CYL | AXIS | ADD | |
|---|---|---|---|---|
| OD | -0.25 | -1.50 | 180 | +1.00 |
| OS | -0.50 | -1.75 | 180 | +1.00 |
This person is short-sighted in both eyes with mild astigmatism. They need single vision lenses — straightforward and the most common prescription type.
1. OD and OS — Your Two Eyes
Your prescription is always split into two sides. OD stands for Oculus Dexter — or simply your right eye (RE). OS stands for Oculus Sinister — or simply your left eye (LE). Every number on your prescription falls under one of these two columns.
Sometimes you'll see OU, which means both eyes together.
2. SPH (Sphere) — Your Main Power
This is the most important number on your prescription. SPH tells you how short-sighted or long-sighted you are.
A negative number (like -2.50) means you are short-sighted — you can see close clearly but struggle at distance. A positive number (like +1.75) means you are long-sighted — distance is fine but near vision is blurry. The higher the number, positive or negative, the stronger the lens you need.
3. CYL and AXIS — Your Astigmatism
CYL (Cylinder) measures astigmatism — a condition where your eye is slightly oval-shaped rather than perfectly round, causing blurred or distorted vision. AXIS always appears alongside CYL. It is a number between 1 and 180 that tells the lens maker the exact angle at which to place the astigmatism correction. It has no meaning on its own — it only works together with CYL.
4. ADD — For Reading Support
The ADD (Addition) value only appears if you need extra magnification for reading on top of your distance correction. This is common in people above 40 as the eye's natural focusing ability reduces with age. If you have an ADD value, you need progressive or bifocal lenses rather than standard single vision.
ikio Quick Tip: Don't Guess Your Lens Type
Once you have your prescription in hand, our Lens Wizard walks you through selecting the right lens type in 3 simple steps — no optical jargon, no confusion. It takes less than a minute.
At ikio™ eyewear, we believe buying glasses should feel as clear as the vision they give you. Got your prescription ready? Explore our full collection of frames here — starting at ₹1,099, with specs ready in minutes from our Koti lab.