Flexure And Residual Astigmatism Of Opus III Lenses On Toric Corneas.
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Flexure And Residual Astigmatism Of Opus III Lenses On Toric Corneas.
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The study of hard lens flexure and residual
astigmatism began in 1961 with a paper by Neal Bailey. Since then a number of studies using the new RGP materials have been conducted (eg. Harris, 1970; Harris & Rodoya, 1982; Harris, 1982; Herman, 1983; Kochanny, 1984; Pole). The results of these studies indicate that rigid contact lenses flex on toric corneas, thus inducing residual astigmatism. The amount of flexure and residual astigmatism is dependent thickness, on the degree of and the effective corneal toricity, lens base curve to cornea fitting relationship. Pole found that lenses fit steeper than 'k' flexed significantly more than lenses fit on 'k' and flatter than 'k'. A comparative study done by Kochanny revealed that the three most popular RGP materials, Boston, polycon and silcon flexed approximately 0.250/diopter of corneal toricity. The present study was designed to measure the flexure and residual astigmatism of the Opus III lens material. The Opus III is a new generation of styrene based gas permeable hard lenses. The lens is composed of tertiary butyl styrene copolymerized with four other monomers, including silicon, to increase 02 permeability. The Dk value of the new material is 14 x 10-" @ 35°C with a wetting angle of 46 via the captive bubble technique |
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http://hdl.handle.net/2323/4598
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Author (aut): Rautio, Jeffery E.
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This paper is submitted in partial fulfillment of the requirements for the degree of Doctor of Optometry. 11 pages.
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English
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