How to Read a Colored Contact Lens Prescription Correctly

By I-SHA Global | Published: 2026-10-15

Category: How-to Guides

Learn how to read a colored contact lens prescription, including base curve, power, and diameter, so you can order colored contacts correctly.

Quick answer

A colored contact lens prescription shows the same key numbers as a clear lens prescription: power (sphere), base curve, and diameter. Check that all three match your eye exam before ordering colored contacts. If any value is missing or expired, ask your eye care professional for an updated prescription.

Identify the key numbers on your prescription

Your prescription will list values for each eye, usually labeled OD (right) and OS (left). The main numbers are: Sphere (SPH) for power, Base Curve (BC) for the curve of the lens, and Diameter (DIA) for the lens width. Some prescriptions also include Cylinder (CYL) and Axis for astigmatism, but colored contacts typically only come in spherical powers. If your prescription includes CYL and Axis, you may need to ask your eye doctor whether spherical colored lenses are suitable for you.

Match base curve and diameter to your eye

Base curve and diameter affect how the lens sits on your eye. A base curve that is too flat or too steep can cause discomfort or blurry vision. Diameter is the overall width of the lens; a larger diameter can make the colored part more visible, but it must still fit your eye properly. Compare the BC and DIA on your prescription with the specifications of the colored lenses you want to buy. If they don't match exactly, consult your eye care professional before ordering.

Check the expiration date and prescription details

Contact lens prescriptions typically expire after one to two years. Ordering with an expired prescription is unsafe and may be illegal in some regions. Also verify that the prescription is for contact lenses, not eyeglasses—they are not interchangeable. Keep a copy of your prescription handy when ordering colored contacts online. If you're unsure about any term, ask your eye doctor to explain it.

Steps to read your prescription

Locate the sphere (power) for each eye: Find the SPH value for OD and OS. This number indicates the lens power, usually in diopters (e.g., -2.50). If it says Plano or 0.00, you have no refractive error and may only need non-prescription colored lenses, but check with your eye doctor. Checkpoint: Ensure the power matches your current vision needs.
Find the base curve (BC): The base curve is the curvature of the lens, measured in millimeters (e.g., 8.6). It should match the base curve of the colored lenses you plan to buy. A mismatch can cause discomfort or poor vision. Checkpoint: Compare with the product specifications before ordering.
Find the diameter (DIA): Diameter is the lens width in millimeters (e.g., 14.2). A larger diameter may cover more of your eye and change the color effect. Ensure it fits within the range your eye doctor recommends. Checkpoint: Do not exceed the recommended diameter for your eye.
Check for cylinder and axis (if present): If your prescription includes CYL and Axis, you have astigmatism. Most colored contacts do not correct astigmatism. Consult your eye doctor to see if spherical colored lenses are an option for you. Checkpoint: Do not order toric colored lenses unless specifically prescribed.
Verify the expiration date and prescriber information: Prescriptions expire, often after one to two years. Also confirm the prescription is for contact lenses, not glasses. Order only if the prescription is current and valid. Checkpoint: Never order with an expired prescription.

Product facts

One Pick Meari Sun Glow 1Day: One Pick Meari Sun Glow 1Day is made in Korea and designed by I-SHA Korea for a refined K-beauty color lens look with comfortable daily wear. This daily lens is a convenient option if you have a current prescription and want a subtle, warm-toned color for everyday wear.
REBORN RED Rosy Cream 1Month: REBORN RED Rosy Cream 1Month is made in Korea and designed by I-SHA Korea. It is one of I-SHA's best-selling color lens series, loved in Korea and Japan for its soft, refined color design and premium monthly-wear mood. A monthly lens can be cost-effective, but you must follow proper cleaning and storage routines to keep your eyes healthy.