The Return of Hybrid
BY PATRICK J. CAROLINE, FAAO, & MARK P. ANDRé, FAAO
Figure 1. DV's corneal topography demonstrating approximately 2.00D of with-the-rule corneal astigmatism
For many of us, the ultimate "dream" lens for managing regular and irregular astigmatism has always been a combination GP and soft lens design. Surprisingly, the history of these lenses dates back to 1977 when Precision-Cosmet acquired the rights to a rigid-soft bonding technology developed by Erickson and Neogi. This evolved into the first commercially available hybrid contact lens, the Saturn II, in 1985. Sola-Barns Hind purchased the technology and in 1989 it released a new and improved design called the SoftPerm lens. This design featured an 8mm Opus III rigid lens center (Dk/14) in a bi-curve design and a soft 25-percent-water peripheral skirt. The soft peripheral skirt remained its original 25-percent-water HEMA-based material.
In 2001, a California-based research group began developing a new high-Dk hybrid contact lens that would become the SynergEyes lens. The lens incorporates an 8.2mm high-Dk rigid center (Paragon HDS 100, Dk 100) and a 30-percent-water non-ionic soft lens skirt. The overall lens diameter is 14.5mm.
The first of three contact lens designs, SynergEyes A, received FDA approval in September. Two more designs are currently in investigation: the SynergEyes KC, an aspheric lens specifically for keratoconus and post-LASIK ectasia, and SynergEyes PS, for patients who have highly oblate corneas following refractive surgery.
A New Alternative
Figure 2. The desired 30 microns of apical clearance.
We've successfully used the SynergEyes contact lens design for patients in which more traditional GP and soft lens designs failed to provide adequate comfort and/or vision. An example is patient DV, a 22-year-old male competing in college level tennis. He had moderate with-the-rule corneal astigmatism and wore toric soft contact lenses with only moderate visual success (Figure 1).
We diagnostically fit DV with the SynergEyes A contact lens from the 24-lens diagnostic set. We selected a base curve with a radius approximately 0.30mm steeper than flat K (flat K = 7.90mm, base curve 7.60mm).
Studies have shown that it's important that the base curves of SynergEyes contact lenses vault the corneal apex (Figure 2); paradoxically, it's the apical vaulting that prevents late onset tightening. The lens is available in two standard skirt curve radii, 1.0mm and 1.3mm flatter than the base curve radius (Figure 3).
Today, DV wears his contact lenses 16 hours a day and enjoys consistent 20/15 visual acuity. CLS
Figure 3. Profile view of a well-fit Synerg-Eyes lens. Note the apical clearance.
Patrick Caroline is an associate professor of optometry at Pacific University and is an assistant professor of ophthalmology at the Oregon Health Sciences University. He is also a consultant to Paragon Vision Sciences and SynergEyes, Inc. Mark André is director of contact lens services at the Oregon Health Sciences University and serves as an assistant professor of optometry at Pacific University. He is also a consultant for Alcon Labs, CooperVision and SynergEyes, Inc.