How does prism ballast work in contact lenses?

Prism ballast works by maintaining the proper position of contact lenses on the eye through the application of added weight. This design is particularly beneficial for certain types of lenses, such as those used for vision correction in cases of strabismus or for toric lenses that require precise alignment for optimal visual acuity. By incorporating weight into a specific area of the lens, typically the lower part, prism ballast helps the lens remain stable and aligned with the pupil, thereby ensuring consistent visual performance and comfort for the wearer.

The other options do not accurately describe the function of prism ballast. Adjusting lens curvature pertains to the optical design of the lens itself rather than position stabilization. Increasing oxygen permeability relates to materials used in contact lens manufacturing rather than the ballast feature, and preventing color distortion does not pertain to the ballast function, which is solely focused on position maintenance.