Which statement correctly explains why a clinician might select a silicone hydrogel with higher Dk/t for a patient who needs extended wear?

Which statement correctly explains why a clinician might select a silicone hydrogel with higher Dk/t for a patient who needs extended wear?

• A. It lowers the risk of infection by making the lens thicker
• B. It reduces the need for daily cleaning
• C. It increases oxygen delivery to the cornea
• D. It eliminates the need for follow-up

Answer: (C)

The key idea is oxygen delivery to the cornea. When a lens is worn for extended periods, the cornea depends on oxygen passing through the lens material. Silicone hydrogels have much higher oxygen permeability, and a higher Dk/t means more oxygen can reach the cornea despite continuous wear. This helps prevent hypoxia-related issues like corneal edema and reduces stress on the corneal tissue during overnight use. So choosing a silicone hydrogel with high Dk/t directly supports corneal health under extended wear conditions.

The other options don’t address oxygen delivery. Making the lens thicker doesn’t inherently lower infection risk, and the Dk/t value doesn’t determine cleaning frequency or eliminate the need for follow-up care.