How to Read a Colored Lens Prescription Correctly
By DEZZY'S Kleurlenzen|Realist | Published: 2026-10-17
Category: How-to Guides
Learn step-by-step how to interpret your colored contact lens prescription, including base curve, diameter, and power. Avoid common mistakes when buying colored lenses online.
Quick answer
Your colored lens prescription contains three key numbers: base curve (BC), diameter (DIA), and power (SPH). You can find these on your eye doctor's prescription or your current lens box. Never guess these values — ordering the wrong size can cause discomfort or eye damage.
Where to Find Your Prescription Numbers
Your eye doctor gives you a written prescription after a contact lens fitting. This document lists your lens parameters, not just your eyeglass numbers. If you don't have the paper, check the side of your current lens blister pack — every legitimate colored lens box prints BC, DIA, and power clearly.
A common mistake is using your eyeglass prescription for colored lenses. Eyeglass prescriptions don't include base curve or diameter, and the power may differ because contacts sit directly on your eye. Always ask for a contact lens fitting even if you only want colored lenses.
Understanding the Three Main Parameters
Base curve (BC) controls how tightly the lens hugs your cornea. Most colored lenses have a BC between 8.4 mm and 8.7 mm. If the curve is too flat or too steep, the lens may move excessively or feel tight. Diameter (DIA) is the overall width of the lens, usually 13.8 mm to 14.5 mm for colored lenses. A larger diameter creates a more dramatic color effect but may feel less comfortable for smaller eyes.
Power (SPH) corrects your vision and is measured in diopters (e.g., -2.00, -3.50). Negative values correct nearsightedness; positive values correct farsightedness. If you have astigmatism, you may also see a cylinder (CYL) and axis number — not all colored lenses offer this correction, so check availability before ordering.
What If Your Prescription Is Missing a Parameter?
Some colored lens brands list only one base curve or diameter because they are designed to fit a wide range of eyes. For example, many lenses use a standard 8.6 mm BC and 14.0 mm DIA. If your doctor prescribed a different value, do not assume the standard will work — ask your doctor or choose a brand that matches your exact numbers.
Transparante contactlenzen from DEZZY'S have a diameter of 14.0 mm and are available in multiple powers from -1.00 to -4.50 and beyond. They include a free lens case, tweezers, and applicator, making them a convenient choice if your prescription falls within that range.
Step-by-Step: How to Read Your Colored Lens Prescription
- Find the base curve (BC): Look for a two-digit number with one decimal, like 8.6 or 8.7. This is the curvature of the lens in millimeters. It must match your eye's shape to prevent the lens from moving too much or sticking. Common mistake: ordering a lens with a BC that differs by more than 0.2 mm from your prescription. Always match exactly.
- Check the diameter (DIA): This is the lens width, usually between 13.8 mm and 14.5 mm. A 14.0 mm diameter is standard for colored lenses and fits most eyes. Larger diameters give more visible color but may feel less comfortable. Checkpoint: if your prescribed diameter is 14.2 mm, a 14.0 mm lens may feel loose. Stick to your exact DIA.
- Read the power (SPH / PWR): The power is listed with a plus or minus sign and a number (e.g., -2.00). Negative corrects nearsightedness; positive corrects farsightedness. Zero power means no vision correction — you only want the color effect. Common mistake: using your eyeglass power instead of the contact lens power. They can differ by 0.25 or 0.50 diopters.
- Identify any additional parameters: If you have astigmatism, you will see CYL (cylinder) and axis numbers. Not all colored lenses offer astigmatism correction. If your prescription includes these, look for toric colored lenses or confirm with your doctor. Checkpoint: if your prescription has CYL and axis, do not buy standard spherical colored lenses — they won't correct your astigmatism.
- Verify the expiration date and lot number: Every blister pack has an expiration date (EXP) and a lot number (LOT). The EXP shows the last month the lens is sterile. The LOT helps trace the batch if there is a quality issue. Common mistake: using lenses past the EXP date. The material degrades and can cause irritation or infection.
Products That Help You Apply and Store Your Lenses
- Transparante contactlenzen: 1 pair monthly or yearly lenses (2 pieces) + free lens case, tweezers & applicator (dia: 14.0mm). Benefits: yearly lenses, no monthly costs, soft comfortable lenses thanks to water content, oxygen-permeable lenses that do not dry out the eyes. Includes lens case, tweezers & applicator. Powers -1.00 to -4.50. If your prescription matches one of these powers, you get a complete starter kit with tools for hygienic handling — no need to buy a separate case or applicator.
- Holly lens case: This great lens case is new in our assortment! Perfect for on the go. Contents: contact lens case, mirror, tweezers, applicator and solution bottle. Having a compact travel case with a mirror and solution bottle makes it easier to apply lenses correctly when you're away from home — reducing the risk of inserting them inside-out or with dirty hands.
