What is the primary difference between hard and soft contact lenses?

The primary difference between hard and soft contact lenses lies in their material and flexibility. Hard lenses, often referred to as rigid gas permeable (RGP) lenses, are manufactured from a firm, durable material that does not bend or flex. This rigidity allows them to maintain their shape on the eye, providing a consistent refractive surface. Their design often results in clearer vision for patients, especially those with certain vision conditions, as they can correct higher levels of astigmatism.

On the other hand, soft lenses are made from a pliable, hydrophilic (water-attracting) material that allows them to conform to the shape of the eye. This flexibility makes soft lenses generally more comfortable for wearers, as they move with the eye during blinking and are less likely to dislodge. The snug fit also allows for better oxygen permeability, contributing to the overall comfort of the wearer.

This distinction in material and functionality is crucial for selecting the appropriate type of contact lens based on individual needs, comfort levels, and the specific vision correction required. The other options do not accurately summarize the fundamental difference, such as the misconception about thickness, vision quality comparisons, or disposability, which can vary within each lens type and wear schedule.