Which of the following will NOT increase the movement of a tight fitting gas permeable lens?

Enlarging the posterior optic zone of a tight-fitting gas permeable lens will not increase lens movement. A larger posterior optic zone creates a greater area of contact with the cornea, which can lead to a more stable fit and reduced movement. A tight-fitting lens is designed to align closely with the natural curvature of the cornea, and by increasing the size of the posterior optic zone, the lens may actually enhance the centration and stability of the lens on the eye rather than promote mobility.

In contrast, decreasing the sagittal vaulting or decreasing the posterior optic zone can remove some of the stability imposed by the lens's shape, allowing it to move more freely on the eye. Therefore, option B is the correct answer because increasing the posterior optic zone leads to decreased movement of the lens rather than an increase.