continuous wear colloquy
Who Wants to Know About CW? Just About Everyone
BY LORETTA B. SZCZOTKA-FLYNN, OD, MS, FAAO
Continuous wear (CW) contact lenses remain a hot topic. So who's discussing this modality, you wonder? Not just practitioners, but everyone from federal agencies to the public.
The FDA is most interested in the post-approval studies required of lenses that have already received marketing approval for 30-day wear (CIBA Vision's Focus Night & Day, Bausch & Lomb's PureVision and Menicon's Menicon Z). Each must be studied on approximately 5,000 subjects to gather information on the rate of microbial keratitis associated with each product.
The FDA also has MedWatch, a passive reporting system for medical device problems. You can access MedWatch via the FDA's Web site (www.fda.gov/medwatch). Of course, the FDA also continually works with manufacturers on new pre-market approval applications for other 30-day CW lenses and reviews the pre-approval study data.
The National Eye Institute, a division of the National Institutes of Health (NIH), is most interested in the pathology associated with continuous wear. The NIH is funding at least six studies on the clinical or basic science aspects of corneal infection or inflammation associated with overnight contact lens wear. NIH-funded investigators are actively exploring the development of new hyper-Dk materials, alteration of epithelial homeostasis with extended contact lens wear, Pseudomonas aeruginosa binding to corneal epithelium, analysis of "protector proteins" for combating keratitis, and epidemiologic risk factors for mechanical and inflammatory complications with silicone hydrogel lenses.
Interest in Clinical Aspects
The vision science community is specifically interested in published independent research related to continuous wear. A search of PubMed (www.ncbi.nlm.nih.gov/PubMed) revealed at least 15 peer-reviewed papers relating to silicone hydrogel lenses and extended wear published in 2004 in journals including Eye & Contact Lens, Eye and British Journal of Ophthalmology.
Optometry and Vision Science has issued a "Call for Papers" for a feature issue entitled "Contact Lenses: New Materials and Designs, and The Cornea's Response To Their Applications" for spring 2005. This issue reflects the tremendous level of research activity in cornea and contact lenses addressing the pathophysiology of disease, or new material applications and corneal re-shaping strategies that impact the clinical outcomes of extended wear.
Sharing Information Globally
Practitioners around the world are interested in gaining more knowledge on silicone hydrogel lenses. Professional meetings and education continue to highlight extended wear as a topic. Additionally, the Web site www.siliconehydrogels.org came into being. The site features synopses of research, online posters, a section highlighting everyday uses of silicone hydrogels, and a global surveillance section for microbial keratitis. For example, the global surveillance section collects anecdotal reports of microbial keratitis (57 cases have been reported worldwide as of July), together with sections on differential diagnoses, treatment plans and printable patient education pieces.
Patients Want to Know
Lastly, and most importantly, patients are listening. Media campaigns and Internet sites have made an impact as patients come to us asking to sleep in the new "breathable" lenses. It's refreshing to see excitement in our field and a new technology that draws patients into our offices.
Dr. Szczotka-Flynn is an associate professor at Case Western Reserve University Dept. of Ophthalmology and Director of the Contact Lens Service at University Hospitals of Cleveland.