What happens when a lens fits flatter than K in terms of its lacrimal lens?

When a lens fits flatter than the K value (the radius of curvature of the cornea), it results in a thinner center. The lacrimal lens refers to the tear film that forms between the contact lens and the cornea. When a lens is placed on the eye and is flatter than the corneal curvature, it creates a larger tear film layer in the periphery. As a result, the central section of the lens must compensate for this by becoming thinner to maintain proper alignment and fit over the cornea.

This phenomenon occurs because the lens shape and relationship to the corneal curvature influence the tear film. If the center of the lens is flatter, there is less curvature to match the cornea’s natural shape, leading to a lower central thickness. Balancing the lens’s design with the shape of the eye is crucial for optimal vision and comfort. A lens that is too thick in the center could cause discomfort and disrupt the stability of the tear film, hence the importance of understanding this relationship.