title: Hard contact lenses. Medical aspects.
abstract: Hard lenses, corneal and scleral, are still useful in correcting ametropia. They offer better visual acuity and increased field of vision in high myopia, irregular astigmatism, and aphakia. Since their chemical and physical properties are reliable they are likely to be used for some time to come.
mesh_terms: D003261:Contact Lenses / Q000009:adverse effects; D003316:Corneal Diseases / Q000209:etiology; D006801:Humans; D055095:Optics and Photonics; D014786:Vision Disorders / Q000628:therapy