The new gas permeable contact lenses

May 15, 2007

High and hyper Dk values provide us with the opportunity to use larger lens designs, which are especially helpful for post-graft patients or those with large cones or pellucid marginal degeneration.

Key Points

If your patient is primarily interested in crisp, clear vision, then he or she will be delighted with GP lenses. Historically, the drawback with GP lenses has been comfort. Today, GP lenses never have been more comfortable, and the comfort level is only expected to keep getting better. Contact lens manufacturers are on a mission to improve oxygen transmissibility and wetting angles. In fact, since 1998, the FDA has approved high Dk lenses for extended wear up to 7 days.

The first use of GP lenses overnight was for orthokeratology, also called Ortho-K. Although many eye-care professionals thought that consumers would flock to optical dispensaries to be fitted with this alternative to refractive surgery, growth has been slow. In fact, in 1998, 16% of the contact lens-wearing population was using GP products. According to the Contact Lens Council, in 2000, the number of GP users declined to 15% of the overall 34 million contact lens wearers. That small decline in GP usage should not be taken as a sign of their demise, but rather as the motivation for current technological advancements.

If you tried fitting a multifocal GP lens more than 5 years ago and were not impressed, the latest designs make it well worth another try. Eye-care professionals now can choose from a variety of lens designs-simultaneous or alternating (also called translating), aspheric or spherical-and the lenses can correct up to 2.75 D add power.