Brief Lay Background
Microbial keratitis is an infection of the cornea (the transparent front part of the eye) that may lead to ulcers, scarring and blindness.
There are several disease causing micro-organisms, or ‘pathogens’, which can be bacterial or fungal. In the UK, most cases (90%) are caused by bacteria, with the biggest risk factor being contact lens use.
Microbial keratitis is an ocular emergency and if improperly treated, it can quickly lead to vision impairment, require a corneal transplant or result in eye loss. Globally, around 60% of those with microbial keratitis are left with some impaired vision.
What problem/knowledge gap does it help address
Outcomes are poor due to limitations in healthcare access, poor diagnostic performance and limited treatment options. Current treatments often require hourly administration of eye-drops, meaning that doses are easily missed, and that most of the drug will run out of the eye before it has a chance to work.
A new treatment for microbial keratitis being investigated uses a photosensitiser – a dye that emits ‘reactive oxygen species’ when a specific light is shone onto them. Reactive oxygen species are able to cause damage to any surrounding cells or pathogens. This technique – borrowed from treating another corneal condition called keratoconus – has shown mixed results for microbial keratitis.
Aim of the research project
To develop and test the new photosensitiser therapy in experimental models of microbial keratitis.
Key procedures/objectives
- Grow a variety of microbial keratitis pathogens on a model eye to understand how the pathogens interact with corneal cells.
- Determine optimal dosage by applying the photosensitiser to the corneal infection using different delivery methods, such as eye drops or contact lenses.
- Assess any changes in corneal cells and tissues.
Potential impact on people with sight loss
Delaying treatment for microbial keratitis worsens patient outcomes, compounded by poor diagnostics that fail to identify pathogens in 50% of UK cases and the rise in antimicrobial resistance. If found to be effective, photodynamic therapy using the new photosensitiser could be initiated before a specific diagnosis, as the photosensitiser could be effective against antimicrobial resistant bacteria and fungi.
The current antimicrobial dosing regime causes more than 80% of people being treated for fungal keratitis to be hospitalised for an average of 18 days. A new therapy could reduce the risk of progression, scarring and improve patient overall wellbeing.
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