If a rigid gas permeable lens is too tight, what should be decreased?

When a rigid gas permeable (RGP) lens is deemed to be too tight, the appropriate adjustment to alleviate the tight fit is to decrease the base curve. The base curve of the lens is the curvature on the back surface that conforms to the front of the cornea. If the base curve is too steep relative to the corneal curvature, it creates excessive suction and tightness on the eye. Decreasing the base curve will make the lens flatter, allowing for better movement and reducing the potential for discomfort or corneal distortion.

Modifications to the optical zone, diameter, or thickness do not directly address the fit of the lens in relation to the cornea's curvature. While these factors can influence lens fit and performance, they are not the primary adjustments made to accommodate a lens that is too tight. Thus, focusing on the base curve is the most effective way to ensure proper lens fit and comfort.