What material was used for contact lenses before 1930?

Before 1930, contact lenses were primarily made from glass. This material was used to create hard lenses, which were heavy and could be somewhat uncomfortable for wearers. The glass lenses were typically based on the same principles as eyeglasses, with the curvature designed to correct refractive errors.

The other materials listed did not become prevalent until after this time period. PMMA (polymethyl methacrylate), for example, was developed later and became widely used for soft and hard lenses due to its improved comfort and lighter weight compared to glass. Plastic and other types of polymers also came into play after 1930, enhancing the usability and comfort of contact lenses, but prior to then, glass was the dominant material.