What adjustment should be made if an RGP lens is too flat?

When an RGP (rigid gas permeable) lens is too flat, the appropriate adjustment involves changing the curvature of the lens. A flatter lens does not conform adequately to the tear film and the shape of the cornea, which can lead to poor fitting and discomfort for the wearer.

Changing the curvature means adjusting the back surface of the lens to become steeper. This improvement in the curvature can enhance the lens's alignment with the cornea, providing better stability, comfort, and visual acuity. A steeper lens can create more appropriate apical clearance allowing for optimal tear flow underneath the lens, which is essential for oxygen supply and comfort.

Other options do not address the problem effectively. Reducing the diameter does not directly affect the fit related to curvature. Enlarging the optical zone alters visual performance but does not improve fit related to corneal shape. Increasing lens thickness might be done for other reasons, but it does not address the immediate issue of an inadequate curvature resulting from a lens being too flat. Therefore, changing the curvature ensures that the lens adequately fits the individual's corneal profile, improving the overall performance and comfort of the lens.