Commenting on the FDA Panel Meeting on Lens Solutions
BY MILTON HOM, OD, FAAO
Decades ago, the Incredible Shrinking Man was a classic sci-fi movie about a man slowly diminishing in size. He joins the circus, fights oversized spiders and forages for food while continually shrinking. At the end of the movie, he diminishes into nothingness. The recent FDA Ophthalmic Devices Panel meeting called to discuss issues related to contact lens care solutions had me thinking the same thing about lens care and no rub labeling. The font size of the no rub type on many lens care solution cartons seems to be getting smaller.
Are we witnessing the incredible shrinking no rub label? At one time prominent, it seems most manufacturers have backed off from promoting no rub. No rub has changed from a highly beneficial feature to an option, and now it may become extinct.
The Importance of Rubbing
As I have lectured across the country, I've found that audiences are overwhelmingly in favor of rubbing and rinsing. Surveys have shown that more than 70 percent of eyecare practitioners prefer a rub-and-rinse regimen. At the FDA Panel meeting, Charlotte Joslin, OD, presented a statement from the American Academy of Optometry strongly urging the FDA to require "rub and rinse" on labels of all multipurpose solution systems. Dr. Joslin stated that a full rubbing, rinsing and disinfection regimen removes bacteria, fungi and Acanthamoeba from lens surfaces. Not rubbing and rinsing allows more microbes to survive on the lens surface. While reading Dr. Joslin's remarks, it reminded me of Radford's work (1995), which found a 3.5-fold risk for Acanthamoeba keratitis (AK) amongst those cleaning with a surfactant cleaner less than twice a week.
But remember, there are two sides to every story. Looking closer at the article by Joslin and co-workers on the association of solution use and AK (2007), the authors suggest there is a "pattern of risk" with certain behaviors, including lack of rubbing; however, they did not find a significant relationship between no rub and AK. My thinking is that rubbing and rinsing steps may offer a nice safety net for disinfection, especially in view of noncompliant behaviors with many of our patients.
Time and Corneal Staining
Another wrinkle in the discussion about solution-related corneal staining emerged at the Panel meeting. The Panel members were asked to discuss their recommendation for an additional clinical study follow-up visit at two hours to assess corneal staining. Some leading eyecare practitioners and experts presented that there is no evidence of a correlation between corneal staining and eventual microbial keratitis. For me, this issue had already been resolved by Fleiszig's definitive work, which showed that the presence of corneal staining is not a direct link to microbial keratitis.
The two-hour time point was the centerpiece of the industry-sponsored Andrasko (2007) and Garofolo (2005) studies. Following the same methods as Andrasko, a new study by Kislan (AOA Poster session 2008) shows that Opti-Free Express and Opti-Free Replenish stained much more at the 30-minute time point than what Andrasko reported at two hours. During the public portion of the meeting, some argued that assessing corneal staining at two hours was an arbitrary time point, and this was not considered a valid predictor of any future corneal event. In the end, the Panel recommended that the FDA should not require a two-hour assessment in an application nor in any lens or lens care guidance because of the insufficient data available at this time.
One area of agreement at the meeting was the importance of Acanthamoeba testing. But if you ask which solution is effective, there is great confusion. Almost every manufacturer will claim effectiveness for their system. Peroxides are effective, but only when soaked in 3% concentration for six hours. Unfortunately, some peroxide systems are neutralized within minutes, so effectiveness has been questioned.
I think ReNu MultiPlus probably has the best data to date showing multipurpose solution effectiveness against Acanthamoeba. These data show a significant log reduction against trophozoites and cysts within the four-hour recommended soak time than solutions with a six-hour recommended soak time. ReNu MultiPlus also demonstrated efficacy even in rigorous conditions including a high inoculum of organisms and a high concentration of organic soil — quantities much greater than those likely to be encountered by lens wearers.
Change is in Order
Although the Ophthalmic Devices Panel's recommendations may not necessarily reflect the views of the Food and Drug Administration, my hope is that the recent meeting will result in updated requirements and labeling for contact lens solutions.
Contact lenses are a wonderful invention, and our vision continues to be enriched because of them. CLS
Dr. Hom received a grant from Bausch & Lomb for this article.
To obtain references for this article, please visit http://www.clspectrum.com/references.asp and click on document #153.
Dr. Hom is the author of Manual of Contact Lens Prescribing and Figure 3e and Mosby's Ocular Drug Consult. He practices in Azusa, Calif.