Which statement best describes first-generation SiHy lenses?

Which statement best describes first-generation SiHy lenses?

• A. They require plasma surface treatment and have high oxygen permeability, low water content, and high modulus
• B. They require no surface treatment and have high oxygen permeability
• C. They are classified by macromers with no surface treatment and high water content
• D. They are conventional hydrogels

Answer: (A)

First-generation silicone hydrogel lenses deliver high oxygen transmission by incorporating silicone into the polymer. That silicone content makes the material highly permeable to oxygen, but it also makes the bulk surface very hydrophobic, which can lead to poor wettability and comfort unless the surface is modified. Plasma surface treatment was commonly used to increase surface energy and improve tear film spreading on these lenses, helping them feel more comfortable despite their silicone-rich composition. Because the bulk material relies on silicone, these lenses tend to have low water content and a higher modulus, meaning they’re relatively stiff compared with conventional hydrogel lenses. So the statement that best describes them is the one noting the need for plasma surface treatment and the combination of high oxygen permeability with low water content and high modulus. The other descriptions don’t fit because they ignore the need for surface modification, misstate water content, or incorrectly classify the material as conventional hydrogels.

First-generation silicone hydrogel lenses deliver high oxygen transmission by incorporating silicone into the polymer. That silicone content makes the material highly permeable to oxygen, but it also makes the bulk surface very hydrophobic, which can lead to poor wettability and comfort unless the surface is modified. Plasma surface treatment was commonly used to increase surface energy and improve tear film spreading on these lenses, helping them feel more comfortable despite their silicone-rich composition. Because the bulk material relies on silicone, these lenses tend to have low water content and a higher modulus, meaning they’re relatively stiff compared with conventional hydrogel lenses. So the statement that best describes them is the one noting the need for plasma surface treatment and the combination of high oxygen permeability with low water content and high modulus. The other descriptions don’t fit because they ignore the need for surface modification, misstate water content, or incorrectly classify the material as conventional hydrogels.