What are the main types of contact lenses?

The primary types of contact lenses include soft lenses, rigid gas permeable (RGP) lenses, and hybrid lenses. Soft lenses are made from flexible plastics that allow oxygen to pass through to the cornea, providing comfort and ease of adaptation for most wearers. Rigid gas permeable lenses, on the other hand, are made from more durable materials that maintain their shape on the eye while still allowing oxygen to reach the cornea. These lenses often provide sharper vision compared to soft lenses for some patients. Hybrid lenses combine a central rigid gas permeable zone with a soft skirt around the edges, aiming to provide the benefits of both types in a single lens.

The other answer choices do not cover the main categories of contact lenses appropriately. While hard (or RGP) lenses and soft lenses are mentioned, they miss the hybrid category. Spherical and cylindrical descriptors focus on lens shapes and types, not the categories of contact lenses, and do not account for the materials or types used. Lastly, single vision and bifocal lenses refer to specific lens functionalities related to corrective vision, rather than categorizing lens types based on their construction or fitting characteristics.