What characteristic of a material with a lower DK value indicates its rigidity?

A material with a lower DK value, which signifies a lower oxygen permeability, typically indicates a certain rigidity. Such rigidity means that the material is less compliant and does not flex easily under pressure or stress. This characteristic limits the ability of the lens to adapt to the movements of the eyelid blinking or changes in the eye's shape, resulting in a more stable but less flexible material.

In contact lens materials, DK value is critical because it affects how much oxygen can pass through to the cornea. While lower DK values can also be associated with other properties, the rigidity aspect is most closely related to the decreased likelihood of flexing. Thus, materials with lower DK values provide enhanced stability and less deformation when subjected to external forces, making them less flexible overall.