According to a new study, a naturally occurring material has been found to be an effective disinfectant for contact lenses worn by millions of people worldwide.
Microbial keratitis is one of the most severe potential complications for contact lens wearers, involving an infection of the cornea caused by bacteria, most commonly Pseudomonas aeruginosa.
Prior studies have shown that existing disinfection solutions are not effective in preventing biofilms, which are bacterial accumulations that adhere to the lenses‘ surface.
Hydroquinone, an organic compound found in the bark of some trees, has been known to have bactericidal effects against Pseudomonas aeruginosa and several other clinically important pathogens, including Staphylococcus aureus, Escherichia coli, and Klebsiella pneumoniae.
A team from the University of Portsmouth in England and the Naresuan and Pibulsongkram Rajabhat Universities in Thailand has investigated the potential use of multi-purpose solutions (MPS) containing hydroquinone as a disinfectant for contact lenses.
They studied the antibacterial, anti-adhesion, and anti-biofilm properties of MPS formulated with hydroquinone and compared them with two commercial MPS, Opti-free Replenish and Q-eye. The natural compound killed 99.9% of the bacteria at the time of disinfection.
An article published in „Antibiotics“ states that these findings could be helpful in the development of novel disinfectants to combat P. aeruginosa bacteria.
Commercial disinfection solutions, composed of a range of chemicals, can sometimes cause reactions with painful side effects.
We wanted to show that new active ingredients from natural products could be an excellent way to limit or reduce the risk of contact lens contamination.
It is exciting to see how this research has progressed, from discovery to exploring potential applications.“
Dr. Robert Baldock, School of Pharmacy and Biomedical Sciences, University of Portsmouth
Up to 3.5 million corneal infections are reported annually, which in extreme cases can lead to permanent eye damage and vision loss. The risk of microbial keratitis doubles when someone wears contact lenses overnight and/or for longer than the recommended daily wear time.
According to the World Health Organization (WHO), corneal blindness resulting from microbial keratitis is becoming one of the leading causes of vision impairment. The WHO has also categorized multi-resistant P. aeruginosa as one of the most concerning pathogens.
Drug-resistant bacteria occur in more than 2.8 million infections and are responsible for 35,000 deaths annually. Antimicrobial resistance occurs when germs change over time and no longer respond to drugs, making the treatment of infections challenging.
Amoxicillin and trimethoprim are commonly prescribed antibiotics to which certain strains of P. aeruginosa have become resistant.
Hydroquinone is already known as an effective treatment for malaria in humans and is also used in the Netherlands to treat nocturnal leg cramps. There is currently limited research on its drug-resistant properties.
The lead author, Sattaporn Weawsiangsang, from the Faculty of Allied Health Sciences at Naresuan University, is currently a visiting researcher at the University of Portsmouth.
She said: „Our initial results suggest that soaking contact lenses in a multi-purpose solution containing hydroquinone may be helpful in preventing contaminations and infections.“
„However, further studies are needed to determine if hydroquinone itself has any side effects or toxicity.“
„We are continuing to test the compound on a range of cells, and so far, the results are really promising. This potential development could contribute to the creation of new disinfectants from natural products that effectively combat P. aeruginosa infections and reduce corneal diseases.“
The article concludes with a recommendation for further research to investigate the effectiveness of hydroquinone on various contact lens materials and against other pathogenic microorganisms.
Weawsiangsang, S., et al. (2024). Hydroquinone Improves the Efficacy of Contact Lens Solutions to Inhibit Adhesion and Biofilm Formation of Pseudomonas aeruginosa. Antibiotics. doi.org/10.3390/antibiotics13010056.