Which technique involves base down prism at the bottom of a front surface toric GP lens to minimize rotation with blinking?

Which technique involves base down prism at the bottom of a front surface toric GP lens to minimize rotation with blinking?

• A. Prism ballasting
• B. Edge lifting
• C. Prism cladding
• D. Rim thinning

Answer: (A)

Stability of a front-surface toric GP lens relies on how weight and lid interaction keep the lens oriented. Placing a small prism with its base at the bottom creates a ballast effect that makes the lower portion of the lens heavier. This vertical ballast leverages gravity and the lower lid to encourage the lens to settle in a base-down position, which minimizes rotation whenever the eye blinks. The tiny prism adds just enough prismatic effect to oppose any tendency of the toric orientation to drift, so the axis stays aligned with the eye’s meridians. Other techniques adjust edge or rim features to influence how the lens sits, but this approach specifically uses base-down prism to produce a stable, bottom-heavy orientation that resists rotation.

Stability of a front-surface toric GP lens relies on how weight and lid interaction keep the lens oriented. Placing a small prism with its base at the bottom creates a ballast effect that makes the lower portion of the lens heavier. This vertical ballast leverages gravity and the lower lid to encourage the lens to settle in a base-down position, which minimizes rotation whenever the eye blinks. The tiny prism adds just enough prismatic effect to oppose any tendency of the toric orientation to drift, so the axis stays aligned with the eye’s meridians. Other techniques adjust edge or rim features to influence how the lens sits, but this approach specifically uses base-down prism to produce a stable, bottom-heavy orientation that resists rotation.