Quest for Improved Contact Lens Materials Continues
By Cary Herzberg, O.D.

Silicone hydrogel certainly have been among the most exciting innovations in contact lens material technology. Contact lenses made from the material differ from conventional hydrogel contact lenses in their enhanced wettability, performance and reduction of lipids. They may even become a separate contact lens category as listed by the FDA. Further, the material offers therapeutic benefits as well: 

• It increases the accuracy of IOP measurements compared with the possibility of a lesser accurate mmHg reading due to a conventional hydrogel contact lens�s water content and thickness.
• It provides enhanced drug delivery to the cornea.
• In a piggyback lens system with a GP contact lens, silicone hydrogels correct poor visual acuity and reduce corneal distortion.

Meet the latest advances

Following are my picks for impressive recent advances in contact lenses using silicone hydrogel material.

The hyper-oxygen transmissibility of CIBA Vision�s Night & Day contact lens with a Dk/t of 175 makes it a good choice for many patients. As of the fourth quarter of 2004, the company added �breathable contact lenses� on its package. The complete line of CIBA silicone hydrogels has different wearing schedules for daily wear and up to 30 days of continuous use.

Combining the best features of a silicone hydrogel with a GP material is Lagado Corporation�s ONSI-56 contact lens which can be designed as a spherical, aspheric, toric or bifocal design. It hydrates like a hydrogel lens while offering the visual clarity of a GP contact lens.

Johnson & Johnson, the first company to introduce a disposable soft contact lens, launched their Acuvue with Hydroclear contact lens last year. The internal wetting agent in this silicone hydrogel lens offers such advantages as low dehydration, a soft and flexible material with the highest UVA and UVB blocks, and low protein deposits. The company also promises �end of day comfort� with this newest addition to this Johnson & Johnson�s Vision Care division.

CIBA Vision recently introduced its new O2OPTIX silicone hydrogel contact lens for daily wear. The lens offers oxygen transmissibility of 138 Dk/t @ -3.00 -- five times more oxygen than the leading soft contact lens and 62% higher than the next daily wear silicone hydrogel lens, CIBA says. The company is also seeking approval for overnight wear, as well as readying a toric version for release.

Are you in the loop?

To make sure your practice is on top of the latest in contact lens technology, consider upgrading your contact lens technician, if you have not done so already, to a member or Fellow in the Contact Lens Society of America (call (703) 437-5100 or go to www.clsa.org). And use the many laboratory and on-line in office, training, patient, staff and doctor education resources of the Contact Lens Manufacturers Association & the GP Lens Institute at: www.rgpli.org. or 1-800-344-9060. Join the American Optometric Association�s Contact Lens and Cornea Section; if a Fellow in the American Academy of Optometry, pursue your Diplomate in the Cornea and Contact Lens Section.