Contact lenses can be grouped into which two major categories?

Contact lenses can be grouped into two major categories based on the materials used to manufacture them: rigid lens materials and soft lens materials. Rigid lenses, often referred to as gas permeable lenses, are made of firm materials that allow oxygen to pass through to the eye, providing clear vision with a stable fit. These lenses are known for their durability and are suitable for specific vision corrections and conditions.

Soft lenses, on the other hand, are made from flexible, hydrophilic (water-attracting) materials, making them more comfortable for many wearers. They conform to the shape of the eye and are available in various designs, including those specifically for astigmatism or presbyopia.

This categorization is fundamental in optometry because it helps practitioners determine the most appropriate lens type based on a patient's lifestyle, comfort needs, and vision correction requirements. The other choices pertain to specific classifications within the broader categories or specific functions of lenses, which do not encompass the fundamental material distinction that is foundational to contact lens fitting and selection.