Silicone hydrogel contact lenses, even more than conventional soft contacts, require a rubbing step when cleaning and disinfecting the lenses with “no-rub” contact lens solutions, says a prominent contact lens specialist.

Michael A. Ward, MMSc, FAAO, instructor in ophthalmology at Emory University School of Medicine (Atlanta, Ga.) and director of Emory Eye Center’s Contact Lens Service, says adding the manual cleaning step maximizes comfort, improves vision and reduces the risk of contact lens-related eye infections.

Researchers are finding that one-step (”no-rub”) contact lens solutions often do not completely remove environmental debris, skin oils and make-up from the surface of contact lenses. These lens deposits can cause eye discomfort and vision problems, and may also decrease the effectiveness of lens disinfectants and lead to serious problems, including bacterial and fungal eye infections and Acanthamoeba keratitis.

Silicone hydrogel lenses, which allow more oxygen to reach the cornea than regular soft contacts, are as likely as regular soft lenses to accumulate lens deposits if they are not properly cleaned and disinfected after each wearing period.

If patients at Emory Contact Lens Service are not compliant with a rub-and-rinse lens care regimen and lens deposits are noted, switching to a hydrogen peroxide-based lens care system often solves the problem, Ward told online newsletter Contact Lenses Today (Oct 22).

Another option for people who are prone to contact lens deposits or fail to care for their lenses properly is to switch to daily disposable contacts, which are designed to be discarded after a single use.

What is the best method for cleaning and disinfecting your contact lenses?

In a recent issue of Contact Lens Spectrum, two prominent researchers addressed this issue in a point-counterpoint debate.

Charlotte Joslin, OD, PhD, epidemiologist and assistant professor of ophthalmology and visual sciences at the University of Illinois at Chicago, prefers hydrogen peroxide-based contact lens solutions. She says that a recent study found that only a two-step hydrogen peroxide lens care system was effective against a microorganism that can cause a serious eye infection called acanthamoeba keratitis.

In addition to being proven effective against Acanthamoeba organisms, two-step hydrogen peroxide-based (HPB) contact lens care solutions also are the most effective against bacterial and fungal eye infections, according to Dr. Joslin. She also said that there have been two worldwide recalls of (non-hydrogen peroxide) multipurpose contact lens solutions due to outbreaks of amoeba and fungal eye infections associated with the use of these one-step solutions.

Dr. Joslin’s argument was countered by Craig A. Woods, PhD, research manager at the Centre for Contact Lens Research, School of Optometry, University of Waterloo (Ontario, Canada).

Dr Woods believes multipurpose contact lens care solutions offer the best combination of safety, cost and effectiveness.

He says that one-step (”no rub”) multipurpose solutions are less expensive and easier to use than HPB disinfecting solutions, and contact lens wearers are more likely to use them properly. He says that there have been “only rare reports” of complications associated with multipurpose solutions, and that they are proven safe and effective.

Dr. Woods also says that hydrogen peroxide-based lens care systems require contacts to be exposed to the hydrogen peroxide solution for a significant amount of time, and that single-step HPB systems may not allow sufficient time for complete disinfection.

He says that while the recent outbreaks of eye infections that caused global recalls of certain multipurpose care solutions were “horrendous for the individuals involved,” he believes these were isolated incidents and not representative of the overall performance of multipurpose disinfecting solutions.

The full point-counterpoint discussion of contact lens care solutions featuring Drs. Joslin and Woods appears in the June 2009 issue of Contact Lens Spectrum.

Soon there may be a novel way to reduce the risk of contact lens-related eye infections: antibacterial contact lenses.

Researchers in Australia have discovered that incorporating melimine, a cationic peptide, into the the lens material of silicone hydrogel contact lenses reduced the incidence of contact lens induced acute red eye (CLARE) and contact lens induced peripheral corneal ulcers (CLPU) in rabbit and guinea pig eyes fit with contact lenses and exposed to common infection-causing bacteria.

Peptides are naturally occurring organic molecule formed by the linking of two to 50 amino acids. (Larger sequences of amino acids are called proteins.)

Cationic peptides range in size from 12 to 50 amino acids and have a broad spectrum of antimicrobial activity, including protection from bacteria, viruses and fungi. “Cationic” refers to the positive charge of the molecules, which enables them to interact with and affect negatively charged bacterial membranes.

The researchers concluded that incorporating the cationic peptide melimine into contact lenses may prevent the growth of bacteria on contacts and reduce the incidence and severity of contact lens-related eye infections.

Additional studies are needed to confirm the effectiveness of this approach and the feasibility of commercially developing such lenses.

Source: In vivo performance of melimine as an antimicrobial coating for contact lenses in models of CLARE and CLPU. Investigative Ophthalmology & Visual Science. (Published online ahead of print August 26, 2009.)

Rinsing silicone hydrogel contact lenses with an approved contact lens solution after removing them from the eye removes more than half the protein that accumulates on the lenses, according to a new study.

Researchers at The Ohio State University College of Optometry found that rinsing silicone hydrogel contacts thoroughly as part of a “no rub” lens care system removes protein deposits from the lenses significantly better than foregoing the rinse step.

Subjects participating in the study were fit with silicone hydrogel lenses manufactured by CIBA Vision and then wore the lenses on a daily wear basis for five days. They were instructed to use Aquify Multi-Purpose Disinfecting Solution (CIBA Vision) after each day of wear, following the manufacturer’s “no rub” care instructions.

The study participants then returned to the clinic and their lenses were removed by a gloved examiner. One lens was rinsed with the contact lens care solution and the other was not. Protein was then chemically removed from all lenses and quantified.

More than 50 percent more protein was chemically extracted from the lenses that did not undergo the rinse step after removal from the eye.

The results of the study suggest silicone hydrogel lenses have significantly less protein build-up if they are thoroughly rinsed with a multi-purpose contact lens care solution when removed from the eye. Including this rinse step as part of a “no rub” care system therefore may decrease the risk of contact lens discomfort and contact lens-related eye infections.

A full report of the study appears in the August 2009 issue of Optometry and Vision Science.