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Myrnah, the ophthalmic clinical officer in Thyolo, attends to a patient

Microbial keratitis is an infection of the cornea that may lead to ulcers, scarring and loss of sight. The risk factors and organisms that cause microbial keratitis are unknown in Malawi meaning that treatment is limited and outcomes are poor. One of the barriers to identifying the organisms responsible has been the difficulty in collecting samples from the cornea. This has depended on the use of sharp instruments and specialist equipment, which are not available in resource deprived settings as you find in Malawi. St Paul's Eye Unit doctor, Tobi Somerville, has been working in collaboration with the Department of Eye and Vision Science at the University of Liverpool, testing a novel method for identifying the cause of the infection.

She spent three months at the Malawi-Liverpool Wellcome Trust Clinical Research Programme in Blantyre, running a pilot study collecting corneal samples at Lions SightFirst Eye Hospital and Thyolo District Hospital. She used a ‘corneal impression membrane’ technique, developed by Professor Stephen Kaye which involves applying filter paper to the front of the eye. The paper is then placed in broth and transported to the laboratory for microbiological identification.

Tobi tested 72 patients with microbial keratitis, taking both corneal impression membranes and conjunctival swabs. The results showed high levels of Gram +ve bacteria, and more surprisingly low levels of fungal infections. In addition, a much higher isolation rate (the proportion of samples in which microbes were positively identified) was achieved than the 20-30% typically achieved through traditional corneal scraping methods.

Tobi (centre) with Dave (left) and Myrnah, both ophthalmic clinical officers in ThyoloWith the help of a dedicated team of Malawian ophthalmic registrars at Lions SightFirst Eye
Hospital, Tobi plans to bring the study cohort up to 200 patients, but the results so far are very encouraging. A corneal sampling method that enables comparative isolation rates and does not require specialist equipment or training offers an alternative to existing techniques. If this can be implemented in Malawi and other resource deprived settings it will considerably increase our understanding of the microbiological profile of microbial keratitis and enable targeted diagnostic and treatment strategies to be developed.

Professor Kaye is also working with Eye & Vision Science staff on a second microbial keratitis project; an antimicrobial contact lens which can incorporate antibiotics and antifungals into the surface, and can be used to prevent and treat microbial keratitis.
 
This is the third research project St Paul's staff have been working alongside the Department of Eye and Vision Science staff in Malawi. The others include tackling diabetic retinopathy and diagnosing cerebral malaria in comatose children.

Further information

Dr Somerville’s project is being funded by Fight For Sight and the British Council for the Prevention of Blindness.

Professor Kaye is also working with Eye & Vision Science staff on a second microbial keratitis project; an antimicrobial contact lens which can incorporate antibiotics and antifungals into the surface, and can be used to prevent and treat microbial keratitis.

To discover other work being conducted in Malawi by St Paul's staff read: diabetic retinopathy in Malawi and diagnosing cerebral malaria in comatose children.