What effect does Sorbic Acid have on contact lenses?

Sorbic Acid is a preservative commonly used in various products, including contact lens solutions, due to its antimicrobial properties. The correct answer relates to its potential side effects on contact lenses. When Sorbic Acid is used in certain solutions, one effect observed is that it can lead to a yellowish or brown discoloration of the lenses over time. This occurs because Sorbic Acid can interact with the materials used in the lenses, resulting in a change in their color.

While Sorbic Acid does serve to prevent microbial growth, which is beneficial, that specific effect does not describe the primary result on the lenses themselves. The other options about enhancing hydration and improving visibility are not relevant to the chemical properties of Sorbic Acid as they pertain to lens material or performance. Thus, the primary characteristic linked to Sorbic Acid and contact lenses is the discoloration, which is why that answer is recognized as the correct one.