contact lens care
Caring for Silicone Hydrogel Contact Lenses Part 3
In parts 1 and II of this three-part series, I described the properties of the silicone hydrogel materials and discussed the lens care systems that the FDA has approved for them. In this column I'll highlight the known incompatibilities between certain care products and certain silicone hydrogel materials.
Two care system contraindications appear on contact lens package inserts:
1. The Advanced Medical Optics (AMO) UltraCare Disinfecting System or any of its components (Ultra-care Disinfecting Solution, Ultra-care Neutralizing Tablets, Lens Plus Daily Cleaner and Ultrazyme Enzymatic Cleaner) with PureVision (Bausch & Lomb) lenses. NOTE: This precaution is specific to Ultracare and PureVision. Other hydrogen peroxide systems are acceptable for use with PureVision and other silicone hydrogel materials. Clear Care (CIBA Vision) has received specific FDA indication for use with silicone hydrogels.
2. Solo-care (CIBA) with Acuvue Advance (Vistakon) lenses. It alters the parameters of this lens. NOTE: The other polyhexamethylene biguanide (PHMB) systems ReNu MultiPlus (B&L), Complete (AMO) and Aquify MPS (CIBA) do not cause this effect with Acuvue Advance. Solo-care is no longer on the market.
Researchers Study Solutions
Although there are many anecdotal reports regarding silicone hydrogel-solution-cornea interactions, following are the results from various well-controlled, randomized studies of silicone hydrogel materials and care systems:
Jones et al (2002) discovered that, in 50 patients fit with PureVision lenses, 37 percent of patients using ReNu MultiPlus demonstrated corneal staining consistent with a solution-based toxicity reaction, while two percent of patients using Opti-Free Express (polyquaternium-1, Alcon) developed similar staining.
Amos (2004) studied patients wearing Night & Day (CIBA) lenses and found marginally less overall staining for patients using AOSept Plus (hydrogen peroxide, CIBA) than for patients using Opti-Free Express. In addition, no AOSept patients exhibited atypical staining, as opposed to two of 25 (eight percent) using Opti-Free Express.
Jones (2004) fit 20 lens-related dry eye patients in both PureVision and Night & Day lenses and alternated each group with ReNu MultiPlus and AOSept. He found no significant difference from baseline staining in patients using AOSept, but 47 percent of ReNu-PureVision and 21 percent of ReNu-Night & Day eyes showed staining.
Lastly, Amos (2004) studied two PHMB-based regimens ReNu MultiPlus and Aquify MPS when used with Night & Day. At the end of one month, Amos found that 24 percent of the patients using ReNu MultiPlus exhibited atypical staining, as opposed to none of the Aquify MPS patients.
Again, this study illustrates that PHMB is not the real culprit. Rather, it's a more complex solution-material interaction that we don't yet completely understand.
Don't Assume Anything
The bottom line is, if any unusual sign or symptom occurs after switching a patient to a silicone hydrogel material, don't assume the cause is the material alone. Consider a material-solution interaction and then report your findings. Help us add to the growing body of knowledge concerning these new materials, the silicone hydrogels.
For references, visit www.clspectrum.com/references.asp and click on document #117.
Dr. Gromacki is in group practice in Burke, Virginia, and has served as a faculty member at the University of Michigan Department of Ophthalmology and Visual Sciences.