Which base curve would loosen the fit of a 8.70 soft lens if the diameter is kept constant?

When considering how to alter the fit of a soft contact lens, the base curve is a crucial factor. The base curve refers to the curvature of the lens and affects how tightly or loosely it conforms to the shape of the cornea.

Opting for a base curve that is larger than the original will lead to a looser fit. This is because a larger base curve results in a lens that has a flatter profile, which means it will align less closely with the natural curvature of the cornea. In this case, changing to a base curve of 8.90 from an 8.70 soft lens offers just this effect. The change to a flatter curve causes the lens to sit more loosely on the eye.

On the other hand, selecting a smaller base curve would cause the lens to fit more snugly against the cornea, thus tightening the fit. The choices that involve base curves of 8.30, 8.40, and 8.60 would result in a tighter fit since they are smaller radii compared to the original lens. Each of these options represents a curve that would align more closely with a typical corneal shape, thereby reducing the space between the lens and the corneal surface, which is not conducive to