What do Dk and Dk/t measure in GP lens materials, and why are they important for corneal health?

What do Dk and Dk/t measure in GP lens materials, and why are they important for corneal health?

• A. Dk is tear permeability; Dk/t is permeability divided by tear volume.
• B. Dk is the material’s oxygen permeability; Dk/t is permeability divided by lens thickness, representing oxygen delivered to the cornea; higher values reduce hypoxic stress.
• C. Dk measures water content; Dk/t measures lens elasticity.
• D. Dk describes lens oxygen supply to the air; Dk/t is nothing to do with oxygen.

Answer: (B)