A bifocal<unk>  eyeglass lens A pair of contact lenses, positioned with the concave side facing upward A<unk>  is a lens (i.e. a transmissive optical device) that is typically worn in front of the eye to improve daily vision. The most common use is to treat refractive errors: myopia, hypermetropia, astigmatism, and presbyopia. Glasses or "spectacles" are worn on the face a short distance in front of the eye. Contact lenses are worn directly on the surface of the eye. Intraocular lenses are surgically implanted most commonly after cataract removal but can be used for purely refractive purposes.
Corrective lens
Trifocal lenses
Boston keratoprosthesis
Multifocal intraocular lens
Browline glasses
Pre-Descemet's Endothelial Keratoplasty
Artificial iris
Windsor glasses