What type of lens design includes prism ballast, double slab-off, and peri-ballast?

The correct answer is that soft toric lenses include prism ballast, double slab-off, and peri-ballast designs. These design features are specifically implemented in soft toric lenses to help stabilize the lens on the eye and maintain its proper orientation.

Prism ballast is a technique that adds weight to the bottom of the lens, allowing gravity to keep the lens in the correct position as the wearer moves their head or eyes. This is particularly important for toric lenses, which are designed to correct astigmatism and must remain oriented correctly to provide optimal vision.

Double slab-off is another design feature that modifies the edges of the lens to reduce lens thickness and improve comfort while also maintaining the necessary weight distribution for stabilization. Peri-ballast refers to modifications made in the peripheral areas of the lens to enhance stability while minimizing discomfort.

These features are tailored to the unique needs of individuals with astigmatism, making soft toric lenses the correct categorization for this type of design. Other lens categories such as hard contact lenses, spherical lenses, and multifocal lenses do not typically incorporate these specific design features aimed at stabilization for toric correction.