Which statement about Dk and scratch resistance is correct?

Which statement about Dk and scratch resistance is correct?

• A. Lower Dk more scratch resistant
• B. Higher Dk more scratch resistant
• C. Dk has no effect on scratch resistance
• D. Scratch resistance depends on thickness

Answer: (A)

Dk measures how easily oxygen passes through a lens material, while scratch resistance is a surface property tied to the material’s hardness and how well the surface is finished. In many GP materials, higher Dk materials are more flexible and tend to be softer, making them more susceptible to surface scratches. Conversely, lower Dk materials tend to be stiffer and harder, which helps resist scratching. So the idea that a lower Dk is associated with greater scratch resistance best fits how these properties interact. Thickness isn’t the primary factor for scratch resistance; it affects handling and durability more generally, not the inherent resistance of the surface to scratching.

Dk measures how easily oxygen passes through a lens material, while scratch resistance is a surface property tied to the material’s hardness and how well the surface is finished. In many GP materials, higher Dk materials are more flexible and tend to be softer, making them more susceptible to surface scratches. Conversely, lower Dk materials tend to be stiffer and harder, which helps resist scratching. So the idea that a lower Dk is associated with greater scratch resistance best fits how these properties interact. Thickness isn’t the primary factor for scratch resistance; it affects handling and durability more generally, not the inherent resistance of the surface to scratching.