Contact Lens Design & Materials
New Entries into the SiHy Daily Disposable Category
BY NEIL PENCE, OD, FAAO
While practitioners are aware of the significant advantages of daily disposable (DD) contact lenses in terms of convenience and ocular health, the primary expectation of patients is one of exceptional comfort. Several new DD lenses have been introduced recently. While the higher oxygen and accompanying health benefits are nice attributes, the anticipated success of both will rest more on providing excellent comfort.
Acuvue Oasys 1-Day
Johnson & Johnson Vision Care has added Acuvue Oasys 1-Day with HydraLuxe technology to its family of DD lenses. The platform of the lens is the same silicone hydrogel (SiHy) material as other Acuvue Oasys products: senofilcon A with 38% water content and a Dk of 100. This does not mean that they are exactly the same material, however, as slight changes or enhancements can occur while still remaining within the U.S. Food and Drug Administration tolerance guidelines. The manufacturer suggests that slight modifications in cross-linking within the material have occurred, which may impact the binding of moisture within or on the lens.
Acuvue Oasys 1-Day has a larger diameter (14.3mm) compared to the traditional Acuvue Oasys and comes in two base curves (8.5mm and 9.0mm). The larger diameter may affect lens centration as well as lens comfort and allows larger optic zones to be utilized. Any resulting optical effects might be most evident in low lighting conditions. The material maintains a Class 1 ultraviolet (UV) blocking rating. The new lens has been rolled out with a wide power range from –12.00D to +8.00D.
Changes in the lens packaging solution attempt to more closely mimic natural tears. These changes, combined with the cross-linking changes, could result in altered moisture effects and retention attributes. Updated manufacturing techniques may provide a smoother surface, which, combined with the enhanced wetting attributes, is designed to achieve the ultimate goal of a very comfortable lens throughout a full day.
CooperVision has introduced MyDay DD contact lenses manufactured in stenfilcon A, a SiHy material that has a 54% water content and a Dk of 80. The lens has an overall diameter of 14.2mm, comes in one base curve (8.4mm), and also has UV blocking characteristics. MyDay has been released with a power range of –10.00D to +6.00D.
Similar to the company’s Biofinity SiHy material, the MyDay lenses have good wetting characteristics without the need for surface coatings or treatments. This is aided in part by the relatively low amount of silicon in the lens (reported by the company as 4.4% of the lens in the wet state). It also allows the lens to have a low modulus and to still provide a higher amount of oxygen transmission compared to hydrogel daily disposables, with a Dk/t of 100 for a –3.00D lens.
While new to the United States, MyDay has been available in parts of Europe for more than a year, and reports from users there suggest a high level of lens comfort. This is another welcome addition to the DD lenses available in the United States.
In related news, Alcon announced the availability of plus powers for its SiHy DD. Having more fitting options in higher-Dk/t DD lenses for a wider range of patients helps us to more safely meet the comfort and health needs for patients who often wear DD lenses for very long days, even with occasional naps. CLS
Dr. Pence serves as associate dean, Clinical and Patient Services, Indiana University School of Optometry in Bloomington, Ind. He is a consultant or advisor to Alcon and Vistakon and has received travel funding from B+L. You can reach him at email@example.com.