What does the base curve mean in contact lenses?

[Marmarth]

What is the use of it when choosing contact lenses?

[Marienthal]

Base curve is a part of your contact lens prescription. The BC number on contact lenses refers to the radius of the sphere that the back of the contact lens describes. It matches the curve of your cornea.

[Marienville]

Base curve in a contact lens means the curve of your eye. This number determines the size of your lens according to the shape and size of your eyes.Most base curves are shown as 8.0 to 9.5.