contact lens materials

Hybrids Are in the News — and Not Just for Cars

BY NEIL PENCE, OD, FAAO

The term “hybrid” has certainly gotten much attention in recent years, mainly as it relates to the combination of gas and electric motors to power certain vehicles more economically.

Those of us in the eyecare industry know about other “hybrids“ in the news — and of course in this case we are talking about contact lenses.

Current Hybrid Lenses

Hybrids refer to contact lenses that have a rigid GP central portion surrounded by a soft lens material skirt. The earliest lenses in this category were introduced as Saturn contact lenses by Preci-sion-Cosmet in the early to mid-1980s. This initial lens concept went through several generations of development and several changes of ownership before arriving at what is offered today as the SoftPerm lens from CIBA Vision. Among the changes in the SoftPerm lens from the original Saturn design was the addition of peripheral curves onto the GP portion and changes to the peripheral curves of the soft skirt.

Activity in the area of hybrid contact lenses increased with the formation of SynergEyes, Inc. The company introduced the SynergEyes A hybrid lens, which became the first in a family of lenses that include SynergEyes KC (for keratoconus), SynergEyes Multifocal (an annular, center-near design), and SynergEyes PS (for post-surgical fittings). One advancement that all of these lenses offer is the option of choosing among different peripheral curves (either two or three options depending on the design) for the soft lens skirt portion. This adds another fitting parameter apart from just the base curve of the GP central portion to allow better refinement of the fit.

Recent Hybrid Developments

Of recent note are a number of new developments from SynergEyes. These include:

1. Increased center thickness of the GP lens portion in the company's Enhanced Profile (EP) version, available in each of the different SynergEyes lens designs. An EP lens provides a center thickness that is 0.09mm thicker than that of the standard lens for each design. This is helpful in reducing some flexure in highly astigmatic corneas. Due to the effect of the soft lens skirt, the increased GP thickness does not significantly alter the fit, centration or comfort of the EP lenses.
2. Introduction of a +0.75D add power to the SynergEyes Multifocal, which accompanies the +1.25D, +1.75D, and +2.25D add powers previously offered. The new add can relieve accommodative strain in early or emerging presbyopes while having little effect on distance vision.
3. Introduction of the Clear-Kone design for keratoconus, which is designed to better vault advanced keratoconic corneas without bearing. This new option may allow better success in some of the most challenging cases.
4. FDA approval to begin clinical trials of hybrid contact lenses utilizing a soft silicone hydrogel material for the skirt portion of the lens. SynergEyes hopes to launch products with this new skirt material in the first half of 2010. Limiting limbal encroachment or neovascularization is very important in post-surgical cases or in eyes that may eventually need corneal surgery.

A Good Option to Consider

As you can see, hybrids are in the news — not just for cars, but for contact lens applications as well. With more options becoming available and the potential to provide significantly increased levels of oxygen to the peripheral cornea, hybrid lenses warrant your consideration for a place in your contact lens armamentarium. 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.