How to Read Contact Lens Prescription: A Simple Guide

By High-Quality Colored Soft Contact Lenses Online in Malaysia | Published: 2026-10-17

Category: How-to Guides

Learn how to read your contact lens prescription step by step. Understand parameters like power, base curve, and diameter so you can order colored contacts with confidence.

Quick Answer

Your contact lens prescription is a small card with numbers and abbreviations that tell you the exact lens specifications your eyes need. The key parameters are power (PWR or SPH), base curve (BC), diameter (DIA), and sometimes cylinder (CYL) and axis. To read it, find each label on your prescription and match the number to the corresponding lens option when ordering.

What Each Number on Your Prescription Means

A contact lens prescription typically includes several fields. The power (often labeled PWR or SPH) is measured in diopters and can be a minus sign (for nearsightedness) or a plus sign (for farsightedness). The base curve (BC) is the curvature of the lens, usually between 8.0 and 9.0 mm. The diameter (DIA) is the overall width of the lens, commonly around 14.0 to 14.5 mm. If you have astigmatism, you will also see cylinder (CYL) and axis numbers.

One common confusion is that a contact lens prescription is not the same as your glasses prescription. Contacts sit directly on your eye, so the numbers can differ slightly. Always use the values written on your contact lens prescription, not your glasses prescription, when ordering colored contacts.

Where to Find Your Prescription

After an eye exam, your optometrist will give you a contact lens prescription card or include it in your patient summary. It lists values for each eye separately—OD (right eye) and OS (left eye). If you have a glasses prescription but not a contact lens one, you need a separate fitting and prescription for contacts. Many online stores, including ours, require you to enter these values during checkout to ensure the lenses fit correctly.

Step-by-Step: How to Read Your Contact Lens Prescription

Step 1: Find the Power (SPH or PWR): Look for the number with a minus or plus sign, e.g., -2.50 or +1.00. This is the lens power needed to correct your vision. The number may be different for each eye. Common mistake: Using the power from your glasses prescription instead of the contact lens prescription. They can differ—always use the contact lens values.
Step 2: Check the Base Curve (BC): The base curve is usually a number like 8.6 or 8.7 mm. It describes the curvature of the lens. If the base curve is too flat or too steep, the lens may not sit comfortably on your eye. Checkpoint: If your prescription does not list a BC, the lenses you choose must have a BC that matches the one your eye doctor measured during the fitting.
Step 3: Note the Diameter (DIA): The diameter is the lens width, typically 14.0–14.5 mm. This affects how much of your iris the lens covers. For colored contacts, a larger diameter (e.g., 14.2 mm) gives a more noticeable color change. Common mistake: Assuming a larger diameter always looks better. It can also feel less comfortable if your eye opening is smaller. Stick to the diameter your doctor recommended.
Step 4: Look for Cylinder (CYL) and Axis (if you have astigmatism): If you have astigmatism, your prescription will include CYL (a number like -0.75) and Axis (a number between 0 and 180). These correct the irregular shape of your cornea. Checkpoint: Not all colored contacts offer astigmatism correction. If you need CYL and Axis, look for toric colored lenses or consult your eye doctor for compatible options.
Step 5: Verify Expiration and Doctor Signature: A valid contact lens prescription usually expires after one or two years. It must also be signed by your eye doctor. Using an expired prescription can lead to incorrect lens fit or eye health issues. Next step: If your prescription is expired, schedule an eye exam before ordering new colored contacts.

How Prescription Parameters Apply to Colored Contacts

CONS Mystery Box [BUY AND GET FREELENS]: CONS Mystery Box [BUY AND GET FREELENS] is a natural daily colour contact lens with option types for Lens Power and Duration. When ordering this mystery box, you need to select your lens power (the same value from your prescription's SPH or PWR field) and choose the duration (daily wear). This ensures the lens matches your vision correction needs.
Gloria Candle Brown 14.2mm, 3 Month 2Pcs: Gloria Candle Brown 14.2mm, 3 Month 2Pcs has a diameter of 14.2 mm and offers Lens Power options. The 14.2 mm diameter is a common size that fits most eyes. You still need to match the lens power from your prescription. If your prescription includes a base curve, check that this lens's BC (usually listed in the product specs) matches or is compatible.
Gloria Candle Brown 14.2mm, 3 Month 2Pcs