what is bc in contact lenses

BC stands for Base Curve, which is the measurement of the back curvature of the contact lens. The BC of your contact lenses should match your eyes natural curve as closely as possible to ensure a better fit when you are wearing your contact lenses. It also means your contact lenses will be less likely to fall out. The base curve determines what type of fit is required for the lens to meet the curve of your eye. BC values range from about 8.0 to 10.0, and the doctor fits the lens with the curvature most appropriate for your eye. If your prescription does not contain a BC value, this is likely because your brand of lens only comes in one base curve.