An extended wear hard contact lens in aphakia. 1979

J W Espy

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.

UI MeSH Term Description Entries
D008297 Male Males
D008689 Methacrylates Acrylic acids or acrylates which are substituted in the C-2 position with a methyl group. Methacrylate
D008875 Middle Aged An adult aged 45 - 64 years. Middle Age
D010101 Oxygen Consumption The rate at which oxygen is used by a tissue; microliters of oxygen STPD used per milligram of tissue per hour; the rate at which oxygen enters the blood from alveolar gas, equal in the steady state to the consumption of oxygen by tissue metabolism throughout the body. (Stedman, 25th ed, p346) Consumption, Oxygen,Consumptions, Oxygen,Oxygen Consumptions
D003261 Contact Lenses Lenses designed to be worn on the front surface of the eyeball. (UMDNS, 1999) Lenses, Contact,Contact Lens,Lens, Contact
D003263 Contact Lenses, Hydrophilic Soft, supple contact lenses made of plastic polymers which interact readily with water molecules. Many types are available, including continuous and extended-wear versions, which are gas-permeable and easily sterilized. Lenses, Contact, Hydrophilic,Soft Contact Lenses,Hydrophilic Contact Lens,Soft Contact Lens,Contact Lens, Hydrophilic,Contact Lens, Soft,Contact Lenses, Soft,Hydrophilic Contact Lenses,Lens, Hydrophilic Contact,Lens, Soft Contact,Lenses, Hydrophilic Contact,Lenses, Soft Contact
D003315 Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous CORNEAL EPITHELIUM; BOWMAN MEMBRANE; CORNEAL STROMA; DESCEMET MEMBRANE; and mesenchymal CORNEAL ENDOTHELIUM. It serves as the first refracting medium of the eye. It is structurally continuous with the SCLERA, avascular, receiving its nourishment by permeation through spaces between the lamellae, and is innervated by the ophthalmic division of the TRIGEMINAL NERVE via the ciliary nerves and those of the surrounding conjunctiva which together form plexuses. (Cline et al., Dictionary of Visual Science, 4th ed) Corneas
D005260 Female Females
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000368 Aged A person 65 years of age or older. For a person older than 79 years, AGED, 80 AND OVER is available. Elderly

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