I often hear about water content and Dk/t value when buying lenses. What do these terms mean, and which one is more important?

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Accepted Answer

Water content refers to how much water the lens material contains. Higher water content may feel comfortable initially, but in some users it can also dehydrate faster. Dk/t refers to oxygen transmissibility, meaning how easily oxygen passes through the lens to the cornea. Both are important, but for long wearing comfort and eye health, oxygen transmission is often a key factor.

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Question: I often hear about water content and Dk/t value when buying lenses. What do these terms mean, and which one is more important?