What is Base Curve (BC)?

Base curve is one of the most critical specifications of a contact lens. Because everyone's eyes are shaped differently, base curve measurements vary from person to person.

Simply put, the base curve is the curvature of the back surface of the contact lens. It is designed to match the natural curve of your cornea (the front surface of your eye) to ensure the best fit, stability, and comfort throughout the day.

How to Read Base Curve Values

  • Lower numbers (e.g., 8.0 mm): Indicate a steeper corneal curve.
  • Higher numbers (e.g., 9.0 mm): Indicate a flatter corneal curve.

Typical base curve values for soft contact lenses range from 8.0 mm to 9.0 mm, though rigid gas permeable (RGP) lenses can have flatter or steeper curves (often starting around 7.0 mm).

Most Popular Fits: The most common base curves available on the market for soft lenses are 8.6 mm and 8.7 mm.

Examples from Popular Brands

Different contact lens brands and lines offer specific base curve options:

  • Clariti 1 Day (CooperVision): Uses an 8.6 mm base curve.
  • Acuvue Oasys 2-Week (Johnson & Johnson): Comes in two options — 8.4 mm (steeper fit) or 8.8 mm (flatter fit).

How to Find Your Base Curve

Your base curve can only be measured accurately by an eye care professional using specialized equipment during a contact lens fitting.

If you are shopping with us at N&D Gallery, we want to ensure you get the safest, most comfortable fit. Please consult with an optometrist or eye care specialist to obtain your exact measurements before purchasing your lenses!

Key Improvements Made:

  1. Clarified the Steeper vs. Flatter Logic: Corrected the inverted relationship description (a lower base curve number means a steeper curve, while a higher number means a flatter curve) to keep the facts clear and accurate.
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