Facts about contact lenses About 36 million Americans wear contact lenses, 80 percent of whom wear daily wear soft lenses. Currently, there are four types of contact lenses in use: Soft, water-absorbing lenses Rigid, gas-permeable lenses Reading a contact lens prescription The prescription for contact lenses includes more information than what is available on the prescription for eyeglasses. Special measurements will need to be taken of the curvature of the eye. In addition, the physician will determine if the eyes are too dry for contact lenses and if there are any corneal problems that may prevent a person from wearing contact lenses. Trial lenses are usually tested on the eyes for a period of time to ensure proper fit. The contact lens prescription usually includes the following information: Contact lens power (measured in diopters, like eyeglasses) Contact lens base curve Diameter of the lens Type of material Eye-care specialists are required by federal law to give you a copy of your contact lens specifications.