If you have ever felt uncomfortable wearing your contact lenses, the issue might not be the brand or material — it could be the base curve. This small number, often overlooked, is one of the most critical factors in how well your lenses fit.

What Is Base Curve?

Base curve (BC) is the measurement of the curvature of the back surface of a contact lens. It is expressed in millimeters and typically ranges from 8.0mm to 9.0mm for soft contact lenses.

Think of it this way: your eye has a specific curvature, and the contact lens needs to match it. If the base curve is too steep or too flat, the lens will not sit properly on your eye.

Why Base Curve Matters

Too Steep (Higher BC Number)

• Lens fits too tightly on the eye
• Reduced oxygen flow to the cornea
• Can cause dryness and discomfort
• Difficult to remove the lens

Too Flat (Lower BC Number)

• Lens slides around excessively
• Blurred or fluctuating vision
• Lens may fall out
• Irritation from constant movement

How to Find Your Base Curve

Your base curve is determined during a contact lens fitting with an eye care professional. They will measure the curvature of your cornea using a keratometer and recommend the appropriate lens base curve.

Standard base curve values:

• 8.3mm – 8.6mm: Most common range for colored contact lenses
• 8.7mm – 8.9mm: Often used for larger diameter or specialty lenses
• 8.0mm – 8.2mm: Less common, used for steeper corneas

Base Curve and Colored Contact Lenses

When choosing colored contact lenses, many buyers focus on diameter and color but ignore base curve. This is a mistake.

At MIOMI, our standard colored contact lenses are manufactured with a base curve of 8.6mm, which fits the majority of wearers comfortably. For OEM/ODM partners, we can customize the base curve to match your target market requirements.

Can You Change Your Base Curve?

No — you should always wear the base curve prescribed by your eye care professional. Switching to a different base curve without professional guidance can lead to serious eye health issues.

Key Takeaway

Base curve is not a number to guess about. Always follow your prescription. For brand owners building a contact lens line, offering the right base curve options for your target market is essential for customer satisfaction and safety.

Need help selecting the right specifications for your market? Contact us — we will guide you through every parameter.