Have you ever looked at your prescription and wondered what all those numbers and symbols mean? Terms like -2.50, +1.75, or CYL can seem confusing at first—but once you understand them, you gain real insight into how your eyes work.
Let’s break it down in a simple and clear way.
👓 What Are “Eye Powers”?
“Eye power” refers to the corrective strength of lenses prescribed to help you see clearly. These values are measured in diopters (D) and indicate how much correction your eyes need to focus light properly onto the retina.
🔍 Understanding the Basic Types of Eye Power
1. Myopia (Nearsightedness) – Negative Power (-)
If your prescription has a minus (-) sign, you are myopic.
- You can see near objects clearly
- Distant objects appear blurred
- Example: -2.00 D
👉 Why it happens: The eyeball is slightly longer than normal, so light focuses in front of the retina.
2. Hyperopia (Farsightedness) – Positive Power (+)
If your prescription has a plus (+) sign, you are hyperopic.
- You may see distant objects clearly
- Near vision can be blurry or strained
- Example: +1.50 D
👉 Why it happens: The eyeball is shorter, so light focuses behind the retina.
3. Astigmatism – Cylindrical Power (CYL)
If your prescription includes CYL, it means your cornea isn’t perfectly round.
- Vision can be blurred or distorted at all distances
- Example: CYL -1.00 @ 180°
👉 Why it happens: The cornea has an uneven shape, like a rugby ball instead of a football.
4. Axis – Direction of Astigmatism
The Axis (0° to 180°) tells us the orientation of astigmatism.
- It doesn’t affect strength, only direction
- Works together with CYL
5. ADD Power – For Reading (Presbyopia)
Usually seen in people over 40.
- Helps with near tasks like reading
- Example: ADD +2.00
👉 Why it happens: The natural lens loses flexibility with age.
📄 Example Prescription Breakdown
OD (Right Eye): -2.00 / -0.50 × 180
OS (Left Eye): -1.75 / -0.25 × 170
- First number → Spherical power (Myopia/Hyperopia)
- Second number → Astigmatism (CYL)
- Third number → Axis
🧠 Why Understanding Your Eye Power Matters
- Helps you choose the right glasses or contact lenses
- Allows you to track vision changes over time
- Makes you more aware of your eye health
