Which type of contact lens has the greatest wettability?

• A. Hydrogel lens
• B. Silicone hydrogel lens
• C. Hydrogel/SiHy lens
• D. Rigid gas permeable lens

Answer: (C)

Wettability is all about how well tears spread and form a thin, stable film on the lens surface. This depends on surface energy and hydrophilicity—the more water-loving the surface, the lower the contact angle and the easier the tear film spreads.

A hydrogel/SiHy lens blends hydrophilic hydrogel characteristics with the oxygen-permeating silicone network. The hydrophilic components draw in and retain water at the surface, giving a higher surface energy and a more wettable, tear-friendly surface. At the same time, the silicone-containing part provides oxygen permeability, but the key for wettability is that the surface remains intrinsically hydrophilic rather than primarily hydrophobic.

Pure hydrogel lenses are very hydrophilic, but silicone hydrogel lenses often rely on silicone components that can reduce surface wettability unless specially treated. Rigid gas permeable lenses are less wettable because their hard, smooth surface does not promote tear spread as readily as a hydrophilic, water-loving surface.

So, the hydrogel/SiHy lens offers the greatest wettability by combining a hydrophilic surface with efficient oxygen transport, supporting better tear film spread and comfort.