 Early corneal lenses of the 1950s and 1960s were relatively expensive and fragile, resulting in the development of a market for contact lens insurance.Replacement Lens Insurance, Inc. (now known as RLI Corp.) phased out its original flagship product in 1994 after contact lenses became more affordable and easier to replace.One major disadvantage of PMMA lenses is that they allow no oxygen to get through to the conjunctiva and cornea, causing a number of adverse and potentially serious clinical effects.