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Troubleshooting contact lens fitting, new specialty lenses
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NEW YORK – The latest in silicone hydrogel and specialty contact lenses were featured Saturday at the Fifth Annual PRIMARY CARE OPTOMETRY NEWS Symposium held here.
David Geffen, OD, and Jennifer Smythe, OD, explored troubleshooting techniques for common silicone hydrogel challenges and highlighted emerging new specialty lenses entering the market.
Power-related issues
Dr. Smythe discussed several power-related problems encountered with non-silicone hydrogels, citing myopic shifts or “myopic creep” induced by low-Dk lenses. She referenced an extended-wear clinical trial that found that at 9 months, low-Dk extended-wear lenses were associated with a 0.3-myopic shift.
“What that might mean is, you might not want to send a patient off with a year’s supply of these lenses, because you may need to problem-solve,” she said. “You want to have that patient back for a 1-month follow-up.”
She also discussed topographical changes with silicone hydrogel lenses that may be caused by inverted lenses. She said inverted lenses do not necessarily cause symptomatic discomfort, but may cause topographical changes similar to gas-permeable lens corneal reshaping. She said although this effect is temporary, practitioners and patients should be vigilant about proper lens insertion.
Lens care issues
Dr. Smythe said because silicone hydrogels are lipophilic, lipid deposits tend to be a problem with the lenses. These lipid deposits also serve as a reservoir for lens care products, she said. “These are difficult to remove without active cleaning,” she said. “We really do have a reason to tell patients that they need to rub those lenses.”
She added that practitioners should recommend that patients use lens care products that are Food and Drug Administration-approved for use with silicone hydrogel lenses. Among these are Aquify, the new Complete, new Replenish and ReNu with MoistureLoc.
“If there is a problem, you have to look at the solution/lens combination, not just the lenses,” she said. Specialty lenses
Dr. Geffen addressed some of the exciting new developments in the area of specialty lens technology. He discussed the new Nike MaxSight, a lens developed by Nike and Bausch & Lomb specifically for sports. The lens, which comes in gray/green and dark amber, selectively filters specific wavelengths of light. Dr. Geffen said the lens filters out 95% of UVA and UVB and filters out 90% of blue light.
He discussed the phenomenon of chromatic aberration, citing that the typical eye participating in sports has 2.3 D of chromatic aberration. “This lens decreases that aberration by 50%,” he said.
When asked whether the MaxSight could have an application for low vision, Dr. Geffen said the lens is most likely too dark for the typical low vision patient to wear functionally. He added that a possible yellow lens may be developed that could be more compatible with the low vision patient.
Dr. Geffen also discussed the iZon Wavefront-Guided Spectacle Lenses by Ophthonix (San Diego) and iZon Wavefront-Guided Contact Lenses by Definition (Optical Connection, San Jose, Calif.).
Dr. Geffen said 80% of myopes have significant higher-order aberration, as do 70% of emmetropes. “This technology has the potential to achieve improved overall visual acuity and greatly reduce aberrations,” he said. The contact lenses should be available nationwide in late 2006, he said.