Gas Permeable Contact Lenses – Introduction Practice Test

When a cornea is irregular, you want a lens that stays centered and provides a smooth optical surface. Using a larger GP lens diameter increases the bearing area over the cornea and extends toward the sclera, which helps the lens seat more securely and resist movement or decentration as the eye blinks and shifts. That steadier alignment also creates a larger tear reservoir beneath the lens, which helps mask surface irregularities and improve vision by smoothing the optical path. The trade-off is that bigger lenses can be a bit more challenging to handle, requiring careful insertion, removal, and cleaning to avoid damage or trapping debris. So the main advantage of a larger diameter in irregular corneas is improved lens stability and tear reservoir coverage, leading to less movement and better centration.