Which statement is true about hydrogel lens water interaction?

Which statement is true about hydrogel lens water interaction?

• A. They have pores in cross-linked polymers, allowing water to enter
• B. They are completely water-insoluble
• C. They repel water
• D. They dissolve in water

Answer: (A)

Hydrogel lenses are hydrophilic, cross‑linked polymer networks that swell by taking in water. Water molecules enter the gel through spaces within the network—the pores or free-volume created by the cross‑linked structure. This water uptake increases the lens’s water content and causes swelling, but the cross-links hold the network together so the material doesn’t dissolve. That balance—water entering the network while the gel remains intact—explains why these lenses are hydrated but not dissolving. They aren’t water-repellent, and they aren’t completely water-insoluble since they do absorb significant water. The idea that water can enter through pores in a cross‑linked polymer best captures how hydrogel lenses interact with water.

Hydrogel lenses are hydrophilic, cross‑linked polymer networks that swell by taking in water. Water molecules enter the gel through spaces within the network—the pores or free-volume created by the cross‑linked structure. This water uptake increases the lens’s water content and causes swelling, but the cross-links hold the network together so the material doesn’t dissolve. That balance—water entering the network while the gel remains intact—explains why these lenses are hydrated but not dissolving. They aren’t water-repellent, and they aren’t completely water-insoluble since they do absorb significant water. The idea that water can enter through pores in a cross‑linked polymer best captures how hydrogel lenses interact with water.