A lens fit characterized by apical touch indicates what type of corneal surface?

When a lens fit is characterized by apical touch, it refers to the relationship between the contact lens and the cornea where the lens makes contact at the apex of the cornea, often indicating a specific contour of the corneal surface. This scenario is commonly associated with an irregular surface, which could be due to conditions like keratoconus or other corneal dystrophies. In these cases, the normal smooth and spherical contour of the cornea is altered, leading to varying curvature that can cause the lens to touch at the apex rather than distribute evenly across the entire surface.

An irregular corneal surface creates a situation where the contact lens does not lay flat across the cornea; instead, it may sit in such a way that only the most protruding area, the apex, touches the lens. This is starkly different from regular, smooth corneal surfaces where lens fitting would ideally achieve more uniform contact across the entire lens. Therefore, the term "apical touch" directly signifies that the cornea is not perfectly spherical or regular in shape, thereby confirming that the correct answer pertains specifically to an irregular surface.