A lot of apical vaulting in an RGP lens indicates what kind of fit?

When a lot of apical vaulting is observed in a rigid gas permeable (RGP) lens, it signifies a steep fit. Apical vaulting refers to the distance between the back surface of the lens and the apex of the cornea when the lens is on the eye. If the lens exhibits significant vaulting, it suggests that the curvature of the lens is steeper than that of the cornea. In this scenario, the lens is not making adequate contact with the cornea at the center, allowing for a space that results in excessive vaulting.

This type of fit is critical because while a steep fit can provide benefits like promoting tear exchange and reducing the risk of corneal abrasion, it may also lead to issues such as lens movement or discomfort if the fit is too steep. Understanding apical vaulting helps practitioners assess lens fitting and make necessary adjustments to the curvature or diameter of the lens to achieve optimal contact and performance on the eye.