PureVision Toric contact lenses from Bausch and Lomb are designed to correct the vision of patients suffering from astigmatism.  The lenses can be worn as daily lenses and some patients may be able to wear them as extended wear lenses for up to a month, depending on advice from their eye care practitioner. PureVision Toric lenses are manufactured with the AerGel silicone hydrogel lens material to improve oxygen transmission and with a light blue visibility tint to help locate the lenses in the solution.

Lens Material
The lens material, balafilcon A, is a copolymer of a silicone vinyl carbamate, N-vinyl-pyrrolidone, a siloxane crosslinker and a vinyl alanine wetting monomer.

Lens Parameters
Base Curve:	8.7mm
Diameter:	14.0mm
Sphere Powers:	-0.25D to -6.00D in 0.25D steps
Cylinder Powers:	-0.75D, -1.25D and -1.75D
Center Thickness:	0.10mm at -3.00D (varies with power)

Lens Properties
Specific Gravity:	1.064
Refractive Index:	1.426
Light Transmittance:	C.I.E. value - at least 95%
Water Content:	36%