Paromita Mondal, B. Optom Student

NSHM Knowledge Campus, Durgapur, India

Microbial keratitis is an acute and localised corneal infection and can have a significant and negative influence on visual function. Certain viruses, bacteria, fungi, and amoebae can be the source of infection. It has been seen that ocular surface disorders, contact lens wear, diabetes, eye trauma or surgery, and lowered immune system are the common factors that can also put individuals at increased risk. There are around 1.2 to 2 million occurrences of corneal blindness due to ocular trauma and corneal ulcers occur each year, 90% of them are in underdeveloped nations depicting.⁽¹⁾ Although, it is uncommon in developed countries, it remains a leading cause of permanent blindness in developing countries like India.

Treatment of microbial keratitis is difficult to manage for eye care professionals as it requires a competent plan to protect eyesight. It is expected that only 50% of eyes would recover with a favourable visual result if the diagnosis and beginning of adequate antibiotic therapy are delayed.⁽²⁾ As the first point of contact, optometrists must comprehend when to refer patients and when not to do so in order to save the sight but treating ocular infection is a major issue across the world because of following reasons:

• Delayed diagnosis
• Diverse variety of pathogen
• Limited access to clinical services
• Ineffective medications
• Rising antibiotic resistance due to developing patterns of bacterial resistance and non-compliance

As a response, there is an increasing demand for a treatment strategy that delivers wide and quick antimicrobial efficacy while minimising toxicity and bacteria resistance. Ease of use, convenience, and therapy availability are additional important motivators worth investigating beyond routine eye drop treatment regimens.

As investigated by Marasini, S. et al., light-based anti-infective technology presents an exciting possibility as it is safe and effective in treating acute and chronic infections. ⁽³⁾ Ultraviolet C (UVC) is a component of the electromagnetic spectrum with wavelengths ranging from 200 to 280 nm, and the mechanism of UVC inactivation of microorganisms is to destroy the genetic material in the cell’s nucleus or nucleic acids in the virus. ⁽⁴⁾ He demonstrated that UVC can minimise morbidity and the number of eyes lost while inflicting no harm to healthy tissue and can be treated at an early stage without knowing what the organism was or if antibiotic resistance was present. Early studies show that relatively low doses of UVC at 265 nm are effective against a variety of bacteria in vitro and in vivo (1 second of treatment). ⁽²⁾

Marasini, S et. al., demonstrated that twice daily 15 second exposures of low intensity (1.93mJ/cm2) 265 nm UVC can safely ⁽⁴⁾ and effectively ⁽⁵⁾ manage highly pathogenic bacterium P. aeruginosa ocular infection. In this preclinical study cornea was demonstrated to heal completely usually within 24 hours of treatment in an in-vivo infection model.

With such ground-breaking innovative anti-infective therapies under research, the future is looking progressively brighter for patients affected by microbial keratitis.

References

1. Whitcher, J. P., & Srinivasan, M. (1997, August 1). Corneal ulceration in the developing world—a silent epidemic. British Journal of Ophthalmology, 81(8), 622–623. https://doi.org/10.1136/bjo.81.8.622
2. Marasini, S., Dean, S. J., Swift, S., & Craig, J. P. (2022, February). Efficacy of antimicrobial UVC in treating infectious keratitis: an in vivo study. Contact Lens and Anterior Eye, 45(1), 101643. https://doi.org/10.1016/j.clae.2022.101643
3. Marasini, S., Zhang, A. C., Dean, S. J., Swift, S., & Craig, J. P. (2021, July). Safety and efficacy of UV application for superficial infections in humans: A systematic review and meta-analysis. The Ocular Surface, 21, 331–344. https://doi.org/10.1016/j.jtos.2021.03.002
4. Marasini, S., Mugisho, O. O., Swift, S., Read, H., Rupenthal, I. D., Dean, S. J., & Craig, J. P. (2021, April). Effect of therapeutic UVC on corneal DNA: Safety assessment for potential keratitis treatment. The Ocular Surface, 20, 130–138. https://doi.org/10.1016/j.jtos.2021.02.005
5. Marasini, S., Dean, S. J., Swift, S., Perera, J., Rupenthal, I. D., Wang, T., Read, H., & Craig, J. P. (2022, July). Preclinical confirmation of UVC efficacy in treating infectious keratitis. The Ocular Surface, 25, 76–86. https://doi.org/10.1016/j.jtos.2022.05.004