PureVision 2 HD lenses are continuation of the latest in a line of advanced silicone hydrogels designed to provide the patient with the highest level of visual performance as well as maintaining the health of the cornea. These lenses are made with advanced technology allowing for optimum comfort and wearability through the course of wear by providing high levels of oxygen and moisture. PureVision 2 HD also possess an aspheric design which results in “HD” or high-definition vision causing less peripheral distortion and making these ideal lenses for higher power prescriptions.
The technology used in the manufacturing process of PureVision 2 HD is nothing less than remarkable. These lenses are comprised of a base matrix of AerGel, the lightest solid substance known to man made up of 99.8% air with extremely resilient properties allowing for conveyance of much needed moisture and oxygen to the eye.
Additionally, these lenses are not only coated but designed with a surface compounding process known as Performa surface. During this stage of manufacturing, the lens is bombarded with electrically charged gas ions; embedding them in the actual matrix of the lens surface and turning silicon into a silicate. The resultant lens is one resistant to debris and protein buildup as well as a highly viscous surface designed to provide the patient with optimum comfort.
PureVision 2 HD lenses also provide six times the amount of oxygen of conventional planned replacement lenses as well as assisting in the maintenance of the fluid equilibrium of the corneal tear film reducing the likelihood of hypoxic stress to the eye allowing the corneas to remain healthy during extended wearing time.
All spherical lenses are designed using a radius of curvature which provides the lens with the power required to correct vision, i.e., nearsightedness, farsightedness, astigmatism, presbyopia. The problem encountered with higher power prescriptions results in a higher order aberration known as spherical aberration in which the light rays at the periphery of the lens are refracted back toward the optical center; paraxial region with the least amount of deviation from the lens’s prescribed power resulting in peripheral distortion.
PureVision 2 HD lenses are designed using an aspheric design. Asphericity reduces the radius of curvature allowing a flatter surface along any meridian of the lens. This has a two-fold effect: first, it provides the patient with a wider field of view and minimizes distortion along the peripheral edge especially in low light situations when the pupil dilates to allow more light to reach the retina exacerbating the aberration. Secondly, since the radius of curvature is allowed to remain fairly flat along the surface, the edge of the lens coming into contact with conjunctival tissue is allowed to more freely move allowing for comfortable wear.
Asphericity, AerGel, and state-of-the-art manufacturing allow PureVision 2 HD lenses to prevent the buildup of proteins, allow more oxygen transmissibility, prevents the colonization of bacteria and a buildup of allergens while providing a high definition view of the patient’s world. This makes these lenses uniquely suited to not only prevent many of the complications associated with contact lens wear, but also provide comfort to the wearer throughout the day.