SOFT CONTACT LENSES

Biofinity

 

CooperVision Biofinity™ Silicone Hydrogel
Patented Aquaform™ technology optimizes the relationship between water and oxygen to deliver excellent comfort, health, and performance CooperVision announced today that its Biofinity™ silicone hydrogel contact lenses are now available for daily wear in the United States. Designed with patented Aquaform™ technology, Biofinity monthly replacement lenses are made with a unique lens material offering higher water content, a lower modulus, and high oxygen transmissibility. These characteristics translate into maximum comfort, optimal health, and excellent performance for the patient.
Biofinity lenses use CooperVision-patented Aquaform technology to create a naturally wettable silicone hydrogel contact lens. Aquaform minimizes concerns over lens dehydration because it establishes hydrogen bonds with water molecules to create a naturally hydrophilic contact lens that retains water within the lens. In addition, wettability is inherent within the material itself, eliminating the need for additives, coatings, wetting agents, or surface treatments.
Aquaform technology also incorporates longer-chain siloxane molecules, which means less siloxane needs to be incorporated into the lens material to achieve high levels of oxygen transmissibility.

The result is a softer, more wettable material that gives better all-day comfort. The aspheric front surface lens design improves visual performance, and the single base curve and back surface design enables fast, easy alignment and a quicker fitting process. A patented molded round edge reduces conjunctival interaction, resulting in continuous wearing comfort for the patient.
“The wettability and high modulus issues associated with silicone hydrogel lens wear are irrelevant with Biofinty. Aquaform technology optimizes the relationship between oxygen and water, creating a softer, more flexible lens material that stays moist and comfortable all day long,” said James Gardner, director, spherical lens marketing, CooperVision. “Biofinity will offer patients a level of comfort never thought possible with a silicone hydrogel lens.”
Biofinity is manufactured from comfilcon A material. The water content of Biofinity is 48 percent, Dk is 128, and Dk/t is 160. The lens features sphere powers from -0.25 to -6.00D, a base curve of 8.6, and a diameter of 14.
In addition, CooperVision will continue to advance its silicone hydrogel portfolio with the introduction of a two-week silicone hydrogel sphere in 2008, as well as a silicone hydrogel toric lens in late 2008. The company will also continue to pursue FDA-clearance for Biofinity as an extended-wear (overnight wear) lens, with approval expected in the second half of 2008.
 
Modulus and Design

The stiffness of a contact lens is determined by the lens modulus and lens thickness. The higher the modulus and the thicker the lens, the stiffer the contact lens. As an example, rigid gas permeable lenses are stiff due to a high modulus value. There is also a general relationship between Dk and modulus. Oxygen permeability tends to be increased in lenses that contain higher levels of silicone. Silicone, in turn, tends to make lenses stiffer. Hence, higher Dk values are inclined to correspond with high modulus (MPa) values. (See figure 1).
In response to this association, there is considerable interest in the new silicone hydrogel, Biofinity (CooperVision), which is due to come to the market sometime within the next year. This lens combines a high Dk (128) with relatively low modulus (0.75), which appears to offer the right combination of Dk to modulus.
It is well established that comfort is of major importance to contact lens wearers. One of the disappointments associated with certain silicone hydrogel lenses is that they appear to do little to solve end-of-day dryness symptoms. In a retrospective study of 334 individual wearing trials of one month or more involving 184 subjects, the comfort levels of six lenses were evaluated. Patients were asked to evaluate overall comfort, dryness and end-of-day comfort on a scale of one to 100, in which the higher the rating, the better the comfort.

Of the six lenses tested, two were silicone hydrogels, and four were conventional hydro-gels. Considering that patient comfort is a major marketing fixation of silicone hydrogels, it was surprising how poorly they fared against the conventional hydrogels in terms of comfort. (See figure 2)
Again, practitioners have high hopes for the next generation of silicone hydrogel lenses. In a clinical trial of Biofinity (comfilcon A) versus the Focus Night & Day and PureVision, Biofinity’s performance was superior in terms of comfort, vision and overall preference. (See figure 3)
Figure 2 INITIAL COMFORT ONE MONTH COMFORT ONE-MONTH DRYNESS