The base curve radius (BCR) is generally very similar to which keratometry reading?

The base curve radius (BCR) is generally very similar to which keratometry reading?

• A. Steeper K Reading
• B. Flatter K Reading
• C. Average K Reading
• D. Maximum K Reading

Answer: (B)

Base curve radius is the back-surface curvature of a rigid contact lens and is chosen to match the cornea’s flatter curvature. Keratometry gives two principal readings: a flatter meridian with a lower diopter value and a steeper meridian with a higher diopter value. The base curve is generally set to be very close to, or slightly flatter than, the flatter keratometry reading because this provides a stable, comfortable fit with proper central clearance and controlled edge lift. If the base curve matched the steeper keratometry reading, the lens would tend to bear centrally and fit too tightly.

Base curve radius is the back-surface curvature of a rigid contact lens and is chosen to match the cornea’s flatter curvature. Keratometry gives two principal readings: a flatter meridian with a lower diopter value and a steeper meridian with a higher diopter value. The base curve is generally set to be very close to, or slightly flatter than, the flatter keratometry reading because this provides a stable, comfortable fit with proper central clearance and controlled edge lift. If the base curve matched the steeper keratometry reading, the lens would tend to bear centrally and fit too tightly.