What was the down side of using silicone/acrylate in hard lenses?

What was the down side of using silicone/acrylate in hard lenses?

• A. Increased oxygen permeability
• B. Prone to non-wetting, deposits, warpage, crazing, and brittleness
• C. Lower density
• D. Excellent wettability

Answer: (B)

The main trade-off with silicone/acrylate hard lens materials is that, while they deliver high oxygen permeability, they tend to be hydrophobic and less wettable by tears. That poor wettability means the tear film doesn’t spread nicely over the lens surface, leading to non-wetting and reduced comfort or fluctuating vision. The silicone-rich surface also makes the lens more prone to deposits from tear film and the environment, which can further impair comfort and clarity. In addition, the material’s silicone content and rigid nature can cause warpage over time and under handling, and it can develop microcracks (crazing) along with overall brittleness, decreasing durability and increasing the risk of fracture. So these drawbacks—the non-wetting tendency, deposit buildup, warpage, crazing, and brittleness—are the downsides that come with silicone/acrylate hard lenses. The other properties listed describe advantages or unrelated traits, not downsides.

The main trade-off with silicone/acrylate hard lens materials is that, while they deliver high oxygen permeability, they tend to be hydrophobic and less wettable by tears. That poor wettability means the tear film doesn’t spread nicely over the lens surface, leading to non-wetting and reduced comfort or fluctuating vision. The silicone-rich surface also makes the lens more prone to deposits from tear film and the environment, which can further impair comfort and clarity. In addition, the material’s silicone content and rigid nature can cause warpage over time and under handling, and it can develop microcracks (crazing) along with overall brittleness, decreasing durability and increasing the risk of fracture. So these drawbacks—the non-wetting tendency, deposit buildup, warpage, crazing, and brittleness—are the downsides that come with silicone/acrylate hard lenses. The other properties listed describe advantages or unrelated traits, not downsides.