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The CONTEX OK™ (siflufocon A) Rigid Gas Permeable Contact Lens for Orthokeratology is indicated for use in the reduction of myopic refractive error in non-diseased eyes. The lens is indicated for daily wear in an orthokeratology fitting program for the temporary reduction of myopia of up to 3.00 diopters. The lens may be disinfected using a chemical disinfection system only. Note: To maintain the orthokeratology effect of myopia reduction lens wear must be continued on a prescribed wearing schedule.

The CONTEX OK™ (orthokeratology) contact lens is a rigid gas permeable contact lens in a reverse geometry design. The lens material siflufocon A, is a fluoro silicone acrylate polymer which contains D & C Green #6 as a color additive. The CONTEX OK™ (orthokeratology) contact lens has the following dimensions: Chord Diameter................Approximately 6.5 to 13.0 mm Center Thickness for Low Minus Lens..................................0.10 to 0.30 mm for Plus Lens:........................................0.20 to 0.70 mm Base Curve........................................6.50 to 11.00 mm Secondary Curves........................ 0.1 to 2 mm. Flatter or Steeper than Base Curve Peripheral Curves........................ 0.1 to 2 mm. Flatter or Steeper than Base Curve Powers........................................-10.00 to +5.00 Diopters Aspheric Lens Eccentricity ................................................................................................................................................... (Oblate, Prolate or Tangent Conic) The physical properties of the lens are: Refractive Index...... 1.43 (Nd at 25°) Light Transmittance... > 92.5% (370-760 nm) Wetting Angle ... 24.0 (Contact Receding Angle) Specific Gravity.... 1.25 Hardness.... 82 Water Content... <1% Oxygen Permeability.....(cm²/sec) (ml O₂ x Hg) 81 x10⁻¹¹Dk at 35°C CONTEX OK™ (orthokeratology) contact lenses produce a temporary reduction of myopia by changing the shape (flattening) of the cornea, which is elastic in nature. Flattening the cornea reduces the focusing power of the eye, and if the amount of corneal flattening is properly controlled, it is possible to bring the eye into correct focus and compensate for myopia. Contact lenses rest directly on the corneal tear layer and can influence the corneal shape. After the contact lens is removed, the cornea retains its altered shape for part or all of the remainder of the day. A retainer lens must be used each day to maintain the corneal flattening, or the myopia will revert back to the pre-treatment level.

The AIRPERM (siflufocon A) Rigid Gas Permeable Spherical, Aspherical, Toric and Multifocal Contact Lens is indicated for daily wear for the correction of refractive ametropia (myopia, hyperopia, astigmatism and presbyopia) in non-aphakic persons with non-diseased eyes. The lens may be disinfected using a chemical disinfection system only.

THE AIRPERM (siflufocon A) RIGID GAS PERMEABLE MULTIFOCAL CONTACT LENSES FOR DAILY WEAR is an aspheric type multifocal which contains an aspherical (conicoid) curve on either the front or back surface. The lens is manufactured by the same method, i.e., lathing, as that used for the AIRPERM (siflufocon A) RIGID GAS PERMEABLE ASPHERIC CONTACT LENSES FOR DAILY WEAR except that the eccentricity of the lens periphery is made higher in order to impart a multifocal effect into the contact lens. The eccentricity for the aspheric single vision lenses varies from 0 to 0.8 and for the multifocal lenses varies from 0.9 to 1.5. All parameters of the AIRPERM (siflufocon A) RIGID GAS PERMEABLE MULTIFOCAL CONTACT LENSES FOR DAILY WEAR are described and measured in exactly the same way as those for the AIRPERM (siflufocon A) RIGID GAS PERMEABLE ASPHERIC CONTACT LENSES FOR DAILY WEAR. The lenses have the following parameters: Chord Diameter Approximately 6.5 to 11.5 mm, Center Thickness for Low Minus Lens: 0.05 to 0.30 mm, for Plus Lens: 0.10 to 0.70 mm, Base Curve 6.50 to 9.00 mm, Powers -20.00 to +12.00 Diopters, Add Powers +1.00 to + 3.00, Eccentricity 0.1 to 1.5. The physical properties of the lens are: Specific Gravity 1.25, Refractive Index 1.43 (589 nm at 25°), Light Transmittance Clear > 92% (380-780 nm), Tinted >88.0% (380-780 nm), Wetting Angle (CLMA Method) 24.0 ± 2, Water Content <1%, Oxygen Permeability 81 x 10-11Dk at 35°C (cm²/sec) (ml O2 x Hg) Polarographic method of I Fatt, Hardness (Shore) 82. The Airperm (siflufocon A) Multifocal Rigid Gas Permeable Contact Lens is available in the lens material siflufocon A a fluorosilicone acrylate polymer which contains D & C Green #6 as a color additive. The aspheric multifocal functions on the basis of a variation in optical power in the form of increasing plus power from the lens center to the periphery. This serves as a bifocal or multifocal add. The aspheric surface is a member of the conicoid family and is defined by the apical radius and eccentricity, e. The eccentricity value describes the rate of flattening of the posterior aspheric surface or the rate of steepening of the anterior surface. The amount of reading addition is the result of the relationship between the apical radius and the eccentricity value.