title: An extended wear hard contact lens in aphakia.
abstract: In reviewing the literature, there are several reports of limited success with both hard and soft contact lenses for continuous or extended wear. Aphakia is the most common indication for continuous wear, especially in monocular aphakes who are unable to insert and remove their lenses for various reasons. Because of its unusual oxygen permeability, silicone is the logical choice of material for an extended wear lens. However, because of the problems in manufacture, as well as its hydrophobic characteristics, poor centering, and problems with proper edging, no silicone lens has had wide clinical application to date. This paper reports on a preliminary study in a group of 21 aphakic patients fitted with the Polycon lens made of a new material consisting of polymethylmethacrylate in combination with silicone. Although gas permeable, the oxygen permeability is probably not adequate to maintain corneal metabolism without some interchange of oxygen containing tears. However, a significant proportion of the patients were able to wear this lens for an extended period of time without removal.
mesh_terms: D000368:Aged; D001036:Aphakia, Postcataract / Q000628:therapy*; D003261:Contact Lenses / Q000592:standards*; D003263:Contact Lenses, Hydrophilic / Q000592:standards; D003315:Cornea / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008689:Methacrylates; D008875:Middle Aged; D010101:Oxygen Consumption; D012828:Silicones; D013997:Time Factors
chemical_list: D008689:Methacrylates; D012828:Silicones