Article Date: 9/1/2001

RGP insights

What Your Laboratory Can Do For You

BY EDWARD S. BENNETT, OD, MSED
September 2001

One of the least understood and, I suspect, least utilized resources is the rigid gas permeable contact lens laboratory. Many practitioners, notably recent graduates, often are not aware of the benefits and resources that laboratories provide.  I surveyed several Contact Lens Manufacturers Association (CLMA) member laboratories to find out what they can do for you.

RGP Laboratory Services

Without doubt, consultation is the most important service RGP labs provide. According to Kevin Hing at Danker Laboratories, "Design consultation is mission critical because it simultaneously provides practitioner success and education about RGP fitting. This, in turn, increases practitioner confidence and comfort in trying rigid gas permeable lenses for other patients." Most laboratories have highly trained ­ often NCLE-certified ­ consultants to answer questions about lens materials, designs (especially bifocals) and troubleshooting.

Labs can also provide same-day shipping whenever possible, reasonable warranty programs, loaner specialty design diagnostic fitting sets and information on new RGP lens designs and products. In addition, several laboratories provide educational programs and workshops to schools of optometry.

RGP Manufacturing Advances

CNC lathing equipment for automated production of base curve, secondary and periphery curves, including custom aspheric front and back surfaces, has resulted in higher quality lenses which are more reproducible and require less polishing. In addition, lathing produces more comfortable lenses by controlling both edge thickness and edge lift and allowing thin lens designs that have less lens mass and better centration. This is complemented by soft pad polishing and increased interferometer use to verify optical quality throughout the production process.

Toric RGP designs are more accurately produced due to manufacturing enhancements including the use of oscillating diamond generators. In addition, more and more laboratories use corneal topography information to assist in fabricating specific lens designs. Pam Scoggins at ABBA says, "With today's lathing equipment and advanced polymers, we can produce aspheric and translating bifocals that are more comfortable, deliver exceptional visual acuity and provide high reproducibility."

The Future of RGP Technology

Several RGP laboratories mentioned two areas of great potential growth for rigid gas permeable contact lenses and manufacturing: myopia control and bifocal designs. According to Hing, "We have seen a significant increase in demand for specialty RGPs, particularly multifocals. Orthokeratology is still a new field in the United States, but upcoming FDA approval of lens designs in high Dk materials such as Boston XO and Paragon HDS may stimulate practitioner interest and acceptance of the procedure."

Likewise, if current studies, including the Contact Lenses and Myopia Progression (CLAMP) study, show that rigid gas permeable contact lenses slow down myopia progression in young people, RGPs should receive positive consumer publicity. The newer thin lens designs with aspheric or pseudo-aspheric peripheral systems should continue to enhance comfort and acuity.

According to CLMA President Keith Parker, "The average consumer today is much more educated and, when presented with the options of improved visual acuity, corneal health combined with the benefits of myopia management, he will more often than in the past choose the gas permeable option."

Dr. Bennett is an associate professor of optometry at the University of Missouri-St. Louis and executive director of the RGP Lens Institute.


Contact Lens Spectrum, Issue: September 2001