What action can increase tear exchange in RGP lenses?

Decreasing the lens diameter can indeed increase tear exchange in RGP (rigid gas permeable) lenses due to the way these lenses interact with the eye's natural tear film. A smaller lens diameter allows for more mobility of the lens on the cornea, which can facilitate the movement of tears between the lens and the eye's surface. This movement helps in flushing out stagnant tears and allows fresh tears to flow beneath the lens, improving overall comfort and enhancing visual performance.

A larger lens might limit this movement and, consequently, the ability to exchange tears effectively. Therefore, adjusting the lens diameter for optimal fitting can be a key strategy in managing tear exchange and promoting the health of the cornea beneath the contact lens.