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.)

The University of Alabama at Birmingham is taking part in a premarket research study of new contact lenses. The research team is evaluating contacts designed for people with presbyopia — an inescapable, age-related condition that causes a loss of near vision after age 40.

In addition to correcting presbyopia, the lenses are made of a “super breathable contact lens material and are much healthier for the eye,” says Dr. Adam Gordon, associate professor and director of the Cornea Contact Lens Clinic at the University.

Gordon says the new multifocal contact lenses will “revolutionize the way people see and encourage the evolution of contacts away from monovision lenses.”

He says that while patients who wish to wear multifocal contacts should understand the limitations of these lenses, he believes the new lenses being studied will be an “improvement in both vision and comfort” for contact lens wearers with presbyopia.

At least 60 percent of contact lenses prescribed in the United States are silicone hydrogel contacts or daily disposable contacts, according to a recent study conducted by the Centre for Contact Lens Research (Ontario, Canada).

The researchers surveyed 158 eye doctors regarding the types of contact lenses they prescribed for a total of 1,654 patients. The survey was part of a larger study designed to assess patient and eye care practitioner compliance with recommended replacement frequency of contact lenses.

The study found:

• Silicone hydrogel lenses were prescribed for 45 percent of patients and daily disposable contacts were prescribed for 16 percent.
• A very large majority of the contact lenses (92 percent) were prescribed for correction of myopia.
• Toric contact lenses for astigmatism were prescribed for 16 percent of patients and multifocal contacts were prescribed for 3 percent.

Also, 12 percent of patients reported wearing their lenses overnight as extended wear contacts. Even among patients wearing daily disposable lenses, 19 percent reported wearing their contacts overnight occasionally, frequently or almost every night.

Source: What contact lens materials are patients wearing? Contact Lens Spectrum. August 2009.

Colored contacts that enhance or alter the color of one’s eyes are most popular among young females, according to a study appearing in Contact Lens & Anterior Eye, the official journal of the British Contact Lens Association.

According to the researchers, annual survey data regarding contact lens fittings show that those wearing the colored soft lenses are more likely to be female (4.6 percent of all soft lenses fitted versus 1.6 percent for males) and younger than those wearing non-tinted soft contacts.

The mean age of people wearing colored lenses is 27 years (range: 16 to 38 years), whereas the mean age of those wearing non-tinted lenses is 33 years (range: 20 to 46 years), according to the survey data.

People wearing color contact lenses also tend to wear the lenses more on a part-time basis and replace them less frequently than non-tinted lenses, the researchers said.

Source: Patterns of fitting cosmetically tinted contact lenses. Contact Lens & Anterior Eye. (Corrected proof, published online June 19, 2009)