Infections of the cornea - the clear, outermost layer of the
eye - are a potentially serious complication of contact lens wear. Many
different risk factors have been identified, including poor contact lens
cleaning and disinfection routines.
Millions of people worldwide use multipurpose disinfecting solutions
to disinfect, clean, rinse, and store their contact lenses. However,
these solutions may not always be effective against bacteria and other
‘Protamine - a natural protein with a proven safety record - may be useful in developing new types of disinfectant solutions for contact lenses.’
Protamine - a natural protein with a proven safety record - may be
useful in developing new types of disinfectant solutions for contact
lenses, revealed a study published in the November issue of Optometry and Vision Science
, official journal of the American Academy of Optometry. The journal is published by Wolters Kluwer.
In laboratory tests, protamine solutions perform at least as well as
current disinfectant solutions in killing microbes that can cause
contact lens-related infections, suggested the report by Mahesh K.
Bandara, and colleagues of University of New South Wales, Sydney.
But more research will be needed to assess the safety and effectiveness
of protamine-containing solutions before they are adopted for broader
use in contact lens care.
Protamine Kills Microbes - Including Causes of Contact Lens Infections
The researchers performed a series of experiments to evaluate the
antimicrobial effects of protamine solutions, with and without additives
commonly used in contact lens disinfectant products. Originally derived
from salmon, protamine is already used for other medical purposes -
especially as an antidote to the anti-blood clotting drug heparin.
Following industry standards, the study tested protamine solutions
for antimicrobial activity against a standard laboratory panel of
microbes, as well as against organisms isolated from patient samples.
Potential toxic effects on cultured cells were evaluated as well.
The results showed significant antimicrobial effects of protamine
solutions. The effects were "dose-dependent" - the higher the protamine
concentration, the greater the microbe-killing effectiveness. Protamine
killed a wide range of bacteria, yeasts, and fungi, including common
causes of contact lens-related infections.
Against most organisms, protamine was even more effective in
solutions containing common additives. In standard tests, the
antimicrobial effects of protamine were comparable to those of
commercially available contact lens disinfectant solutions. All
solutions tested had minimal toxicity indicating that they also had a
good safety profile.
With its broad spectrum of antimicrobial activity and long
history of medical use, protamine could be a useful alternative for use
in contact lens care products.
"This study highlights the potential for protamine to be used for
the development of effective multipurpose disinfection solutions," Dr.
Bandara and colleagues conclude. At least in laboratory studies,
protamine solutions have a "progressive dose-dependent killing effect"
on bacteria and other organisms that can cause corneal infections.
"Protamine represents a new strategy and a very different type of
compound to help defend against ocular infections related to contact
lens use," comments Michael Twa, Editor-in-Chief of Optometry and Vision Science
Further research will be needed to evaluate protamine's stability,
compatibility with contact lens materials, and safety for use with
contact lens care products and the eye.