For Ks less than 45.00 D, we often select a base curve that is

For Ks less than 45.00 D, we often select a base curve that is

• A. Flat
• B. Slightly steeper
• C. The same as Ks
• D. Very steep

Answer: (A)

Ks measures how curved the front of the eye is: lower values mean a flatter cornea, higher values mean a steeper one. When fitting soft lenses, the base curve should follow the corneal shape so the lens sits evenly and moves appropriately with blinking. A flatter cornea (Ks under 45.00 D) is best matched with a flatter base curve, which means a larger radius. This gives a gentler, more even bearing across the cornea, promotes comfortable wear, and maintains good tear exchange. If the base curve were steeper than the cornea, the lens would push on the cornea, creating a tight fit and less comfortable wear. The same or only a slightly steeper curve wouldn’t accommodate the flatter shape as well, and a very steep curve would be even more uncomfortable on a flat cornea. So, choosing a flatter base curve aligns with the flatter corneal shape to achieve a stable, comfortable fit.

Ks measures how curved the front of the eye is: lower values mean a flatter cornea, higher values mean a steeper one. When fitting soft lenses, the base curve should follow the corneal shape so the lens sits evenly and moves appropriately with blinking. A flatter cornea (Ks under 45.00 D) is best matched with a flatter base curve, which means a larger radius. This gives a gentler, more even bearing across the cornea, promotes comfortable wear, and maintains good tear exchange. If the base curve were steeper than the cornea, the lens would push on the cornea, creating a tight fit and less comfortable wear. The same or only a slightly steeper curve wouldn’t accommodate the flatter shape as well, and a very steep curve would be even more uncomfortable on a flat cornea. So, choosing a flatter base curve aligns with the flatter corneal shape to achieve a stable, comfortable fit.