How does decreasing water content in a hydrogel lens affect oxygen availability?

How does decreasing water content in a hydrogel lens affect oxygen availability?

• A. Less oxygen
• B. More oxygen
• C. No change
• D. Variable

Answer: (A)

Oxygen availability through a hydrogel lens hinges on how easily oxygen can diffuse through the hydrated network. In hydrogels, oxygen dissolves and moves primarily through the water-filled spaces, so the lens’s oxygen permeability (Dk) is heavily influenced by how much water the lens contains. More water means more pathways and higher solubility for O2, leading to greater oxygen transmission to the cornea. When water content is reduced, there’s less water to dissolve oxygen and fewer diffusion routes, so the overall oxygen permeability drops. With the lens thickness fixed, this results in less oxygen reaching the cornea. Thus, decreasing water content lowers oxygen availability.

Oxygen availability through a hydrogel lens hinges on how easily oxygen can diffuse through the hydrated network. In hydrogels, oxygen dissolves and moves primarily through the water-filled spaces, so the lens’s oxygen permeability (Dk) is heavily influenced by how much water the lens contains. More water means more pathways and higher solubility for O2, leading to greater oxygen transmission to the cornea. When water content is reduced, there’s less water to dissolve oxygen and fewer diffusion routes, so the overall oxygen permeability drops. With the lens thickness fixed, this results in less oxygen reaching the cornea. Thus, decreasing water content lowers oxygen availability.