CONTACT LENSES TODAY

March 30, 2003

Contact Lenses Today® is edited by Dr. Joseph T. Barr and the staff of Contact Lens Spectrum. This week CLToday® reaches 10,805 readers in 74 countries.

A Future Without Eye Drops?
Anuj Chauhan and Derya Gulsen, of the University of Florida, have developed a technique to encapsulate a test drug in nanoparticles and mix them into contact lens materials. The particles are so small that they don't cloud the finished lenses and they provide slow release of the drug, distributing it into the thin tear layer between the eye and the contact lens. Chauhan has applied for a patent on the technique and estimates that a commercial product is about a decade away. He doesn't expect cost to be prohibitive.

PALs Versus SVLs for Slowing Myopia
Gwiazda, et al., collected data from 469 African-American, Asian, Caucasian and Hispanic children with moderate amounts of myopia OU at four U.S. clinical centers. The children, who ranged in age from six through 11 years, were randomly assigned to receive either progressive-addition lenses (PALs, n=235) or single-vision lenses (SVLs, n=234) and were followed for three years. The results from this trial, called the Correction of Myopia Evaluation Trial (COMET) revealed that the difference in progression of myopia between the PAL and the SVL groups after three years was 0.20D. The treatment effect occurred in the first year of the COMET and was sustained at the same level over the next two years. The results of the COMET suggest that PALs should not be prescribed routinely for slowing myopia progression in children. This study is published in the most recent issue of Investigative Ophthalmology & Visual Science.

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Contact Lens Profitability Varies
CIBA Vision's most recent e-mail survey revealed that 30% of the approximately 160 eyecare practitioners who responded saw their profit per contact lens patient (including professional fees and materials) increase over the past three years because of adjustments in professional fees and in the mix of lenses they use to fit patients. Thirty-seven claimed their profitability stayed the same and 33% said that their per-patient profit declined, attributing the drop to lens material costs and managed care pressures.

OCI Continues Launch of Aberration Control Disposable Lens Line
In January 2003, Optical Connection, Inc. launched the first of its aberration-control contact lenses, Definition AC, in North America. The second launch made Definition AC Toric lenses available in North America. Now the company is producing Definition AC Multifocal disposable contact lenses using its advanced ContinuFlow Moulding System. The lenses consist of four zones of nonlinear multiaspheric power progressions. For more information on any of these lenses, visit http://www.opticonnection.com.

Abstract: Proof That Washing and Changing Lenses is a Good Idea
Researchers in Chandigarh, India, concluded that rinsing contact lenses decreases the chance of colonization by Acanthamoeba catellani and that older lenses have higher chances of colonization. The researchers investigated the adhesibility of Acanthamoeba catellani trophozoites and cysts to hydrogel contact lenses and to human corneas by preparing 120 segments of unworn contact lenses and eight radial segments of corneal buttons from enucleated eyes. Under varying conditions, the investigators added cysts and trophozoites to the lens and corneal segments and checked adhesion at zero, three and 24 hours after the exposure. The trophozoites adhered equally well to the lens and cornea segments. Washing the lenses significantly decreased the adherence of the trophozoites after three hours of incubation. Adherence to unwashed, unworn lenses was much lower than to unwashed, worn lenses.
Sehgal, R; Saini, J; Singh, KD; Bhatti, HS. Acanthamoeba Adherence to Soft Contact Lens and Human Corneal Stroma. Indian J Pathol Microbiol 2002 Jan;45(1):63-7.

Editor's Commentary: The Future: Is It Now?
In 1988, the year after the 100-year celebration of the contact lens, we published a special issue of Contact Lens Spectrum on the future of contact lenses. Since then we've seen great strides toward optimizing contact lenses. These strides include high technology, mass production of quality disposable lenses, super high Dk/t lenses, improved astigmatic and presbyopic treatments and as you see in our first story, and have seen in other stories, a couple of other things we predicted. Eye drops to improve lens wear used before, after or during lens wear are here and will evolve further.

Fitting Tip: An Easy Way to Determine Reading Add
You can more accurately determine the amount of reading addition prescribed for a presbyope by simply handing the patient some reading material and closely observing the distance that he holds it. It's always amazing to see how variable these ranges are from patient to patient. Rather than just prescribing for a typical 16" to 18" reading range behind the phoropter, discussing requirements for the workplace, for hobbies and observing habitual tendencies will allow you to prescribe the add with the least compromise.
-- Michael Feldman, O.D., F.I.O.S.
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