Contact Lens Design & Materials
What’s New in Silicone Hydrogel Lenses?
BY NEIL PENCE, OD, FAAO
Silicone hydrogel materials continue to dominate the soft contact lens market. They offer superior oxygen transmission, the benefits of which are well documented. Until some next-generation material comes along, silicone hydrogels are expected to maintain their dominant market share. Therefore, I believe that new introductions into this material category continue to be newsworthy.
The proliferation of new parameters in mass-produced silicone hydrogels now offer wide availability for patients needing standard spherical, astigmatic, or multifocal designs. Happily, advances have also recently been made for patients who are less well served—those needing custom soft lens designs, and those benefiting from daily disposables.
Contamac’s Definitive material will soon have company in the custom, lathe-cut silicone hydrogel lens segment with the recent FDA clearance of Lagado LSH (Lagado/Menicon). Lagado LSH is a latheable silicone hydrogel material with a water content of 49 percent. Approved custom lens laboratories will be able to produce a wide array of custom lens parameters and designs in this new material, giving us more options for providing higher oxygen transmission to patients who need custom soft lenses. Expect to see a number of made-to-order options from custom lens laboratories before the end of this year.
New Daily Disposable Lenses
In the daily disposable lens segment, Acuvue TruEye (Vistakon) had the category to itself for several years. Sauflon then introduced the Clariti 1day, which is only recently finding some use in North America. It is a 56-percent water content silicone hydrogel lens meant for single, daily disposable use.
Alcon introduced Dailies Total1 in Europe this past year and has now brought it to the United States and Canada. Dailies Total1 is a daily disposable lens with a novel water gradient characteristic. The core of the lens is a 33-percent water silicone hydrogel material that provides excellent oxygen transmission as well as the structure for the fitting and handling characteristics of the lens. From there the lens transitions to an outer, thin surface gel of sorts in which the water content is more than 80 percent, resulting in a very wettable surface that has a low coefficient of friction. More details on the lens structure are available in my Contact Lens Design & Materials column from the June 2013 Special Edition of Contact Lens Spectrum.
Alcon is positioning Dailies Total 1 as a premium contact lens option. Some practitioners may see the lens only as a niche product. Others may be concerned about the price. Younger practitioners would not know (and some old enough to know may have forgotten), but daily disposable lenses were first introduced with pricing at just over $2 a day. As costs moved toward $1 a day, daily disposable prescribing in the United States has increased; but for patients who struggle with comfortable wear or who have dropped out of wear entirely, cost may not be a large issue.
Still to Come
A fourth daily disposable silicone hydrogel lens is on the horizon: CooperVision recently announced its MyDay daily disposable lens, which will be launched in Europe later this year and in other markets in 2014. Clearly, the desire of some for more silicone hydrogel choices within the daily disposable lens category is quickly being satisfied. CLS
For references, please visit www.clspectrum.com/references.asp and click on document #213.
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 B+L, Alcon, and Vistakon and has received research funding from AMO. You can reach him at email@example.com.