contact lens materials
Silicone Hydrogels Updated to Enhance Comfort
BY NEIL PENCE, OD, FAAO
In the July 2008 Contact Lens Materials column, we recapped introductions or changes over the previous year in the silicone hydrogel category. Likewise, over the past 12 months, further product features were introduced that expand the category and address the critical issue of lens comfort, particularly in dry eye patients.
Lens Revision, Introduction
CIBA Vision debuted in early spring 2009 a revised version of its previous Night & Day lens. The new product, Air Optix Night & Day Aqua, has completely replaced the original version. The new lens is in the same material and parameters as the original Night & Day, but incorporates CIBA's patented Aqua moisture system to improve initial lens comfort and duration of lens wettability. A light blue visibility tint has been added, as well as an "OK" eversion mark. Other, smaller lens markings that are visible with the slit lamp remain the same as the previous lens (CIBAZ453 for an 8.4mm base curve, −3.00D lens, for example).
Early 2009 also saw the introduction of a new astigmatic silicone hydrogel lens. The Biofinity Toric (CooperVision) launched in sphere powers from plano to −6.00D with −0.75D, −1.25D, and −1.75D cylinder powers in 10 degree steps around-the-clock. The lens design is patterned after the Biomedics Toric and has extended wear approval for up to seven days. CooperVision anticipates introducing a −2.25D cylinder power and plus sphere powers later this year.
The biggest silicone hydrogel news in 2009 may be the introduction of a second and third multifocal contact lens into this category. Vistakon now has the Acuvue Oasys for Presbyopia lens, made from the same material as its other Oasys lenses. This lens was initially introduced in sphere powers from plano to −6.00D with two add powers labeled "low" and "mid." Vistakon seems to be introducing the lens in a relatively gradual, sustained type rollout.
The second multifocal slated for summer release is the CIBA Vision Air Optix Aqua Multifocal. This lens is in the Air Optix Aqua material and utilizes the same wetting system and additives to the blister solution as well. The lens will be released with sphere powers ranging from +6.00D to −10.00D. Three add powers are available, and the lens has a center-near design.
Existing Lens Changes
Within the last year, a few existing silicone hydrogel contact lenses have experienced some changes to wear indications and parameters. CooperVision received FDA approval to add the indication for extended wear to the Biofinity lens. Since late 2008, Biofinity has been approved for up to one week of overnight wear.
CooperVision extended the range of available minus powers for its second silicone hydrogel contact lens, Avaira, to −12.00D. Additionally, the company has stated that plus powers for Avaira are expected by fall 2009.
Evolving Lens Category
The silicone hydrogel lens material category continues to be one of tremendous growth, and with the increasing multifocal options it should become the dominant material fit in nearly all segments of the soft contact lens market. Further innovations in silicone hydrogel technology should allow continued comfort and wearability for dry eye patients. Additionally, the expansion of parameters in presbyopic designs will allow these materials to be available to a population at high risk for dry eye symptoms. CLS
Dr. Pence is director of the Contact Lens Research Clinic, Indiana University School of Optometry in Bloomington, Indiana. He is a consultant or advisor to B&L, CIBA Vision, and Vistakon, and has received research funding from AMO.