Which factor is not a primary determinant of a lens's oxygen permeability?

Which factor is not a primary determinant of a lens's oxygen permeability?

• A. Water content
• B. Lens color
• C. Thickness
• D. Dk value

Answer: (B)

Oxygen permeability of a lens is governed by how easily oxygen can diffuse through the material and how thick the diffusion path is. The material’s intrinsic permeability (Dk) sets the baseline rate, and a thinner lens lengthens the oxygen supply to the cornea less than a thicker one, increasing transmissibility. Water content can influence Dk in hydrogel lenses because more water within the polymer can raise oxygen solubility and diffusion, altering the effective permeability. Lens color, however, is cosmetic and does not meaningfully change the diffusion pathways or oxygen solubility in the lens material, so it does not determine oxygen permeability.

Oxygen permeability of a lens is governed by how easily oxygen can diffuse through the material and how thick the diffusion path is. The material’s intrinsic permeability (Dk) sets the baseline rate, and a thinner lens lengthens the oxygen supply to the cornea less than a thicker one, increasing transmissibility. Water content can influence Dk in hydrogel lenses because more water within the polymer can raise oxygen solubility and diffusion, altering the effective permeability. Lens color, however, is cosmetic and does not meaningfully change the diffusion pathways or oxygen solubility in the lens material, so it does not determine oxygen permeability.