To increase tear exchange on a RGP lens, which action is NOT recommended?

Increasing tear exchange on a rigid gas permeable (RGP) lens is crucial for maintaining ocular health and comfort, as it allows for better nutrient exchange and debris removal under the lens. Of the options presented, increasing the sagittal depth is not recommended for this purpose.

When you increase the sagittal depth of a lens, you effectively increase the lens's overall height, which can reduce the space between the lens and the cornea. This reduced space would limit the amount of tear film that can exchange under the lens, as there is less room for tears to flow in and out. Adequate tear exchange is vital for preventing dryness and discomfort, so increasing the sagittal depth would be counterproductive in achieving that goal.

In contrast, flattening the peripheral curves, reducing the overall lens diameter, or decreasing the optic zone are all actions that can enhance tear exchange. By altering these features, the lens can fit more appropriately on the eye and create a better tear film reservoir, allowing for more effective tear movement under the lens. Thus, the option of increasing sagittal depth is not conducive to improving tear exchange and is the least recommended action.