Flexure and residual astigmatism with cellulose acetate buterate (CAB) contact lenses on toric corneas. 1982

M G Harris, and K E Sweeney, and S Rocchi, and D Pettit

Thin contact lenses flex on toric corneas, thus changing the residual astigmatism. Our study evaluated the flexure and induced astigmatism of CABCURVE cellulose acetate buterate (CAB) contact lenses on toric corneas and compared the results with those found for polymethyl methacrylate (PMMA) and Polycon lenses. Ten subjects (20 eyes) with corneal toricities ranging from 1.12 to 3.12 D wore six CABCURVE lenses with center thicknesses from 0.10 to 0.20 mm. Flexure and induced residual astigmatism were measured on all corneas with all lenses in a double-masked fashion. We found that all the CABCURVE lenses flexed on the toric corneas and altered residual astigmatism. Both flexure and induced residual astigmatism increased as center thickness decreased, and were greater than with PMMA or Polycon lenses of similar dimensions. These findings should be considered when deciding which lens type to fit on patients with toric corneas.

UI MeSH Term Description Entries
D008297 Male Males
D008768 Methylmethacrylates The methyl esters of methacrylic acid that polymerize easily and are used as tissue cements, dental materials, and absorbent for biological substances.
D002482 Cellulose A polysaccharide with glucose units linked as in CELLOBIOSE. It is the chief constituent of plant fibers, cotton being the purest natural form of the substance. As a raw material, it forms the basis for many derivatives used in chromatography, ion exchange materials, explosives manufacturing, and pharmaceutical preparations. Alphacel,Avicel,Heweten,Polyanhydroglucuronic Acid,Rayophane,Sulfite Cellulose,alpha-Cellulose,Acid, Polyanhydroglucuronic,alpha Cellulose
D003261 Contact Lenses Lenses designed to be worn on the front surface of the eyeball. (UMDNS, 1999) Lenses, Contact,Contact Lens,Lens, 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
D000328 Adult A person having attained full growth or maturity. Adults are of 19 through 44 years of age. For a person between 19 and 24 years of age, YOUNG ADULT is available. Adults
D001251 Astigmatism Unequal or irregular curvature of the CORNEA (Corneal astigmatism) and/or the EYE LENS (Lenticular astigmatism) resulting in REFRACTIVE ERROR. Corneal Astigmatism,Hyperopic Astigmatism,Lenticular Astigmatism,Mixed Astigmatism,Myopic Astigmatism,Oblique Astigmatism,Astigmatism, Corneal,Astigmatism, Hyperopic,Astigmatism, Lenticular,Astigmatism, Mixed,Astigmatism, Myopic,Astigmatism, Oblique,Hyperopic Astigmatisms,Mixed Astigmatisms,Myopic Astigmatisms,Oblique Astigmatisms
D012828 Silicones A broad family of synthetic organosiloxane polymers containing a repeating silicon-oxygen backbone with organic side groups attached via carbon-silicon bonds. Depending on their structure, they are classified as liquids, gels, and elastomers. (From Merck Index, 12th ed) Silicone

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