New research has developed a novel sensor device (microbiosensor) that alerts contact lens wearers when it is unsafe to put contact lenses in their eyes. This new device could reduce the incidence of severe eye infections which occur when dirty contact lenses are worn. These findings are presented at ASM's 55th Interscience Conference of Antimicrobial Agents and Chemotherapy (ICAAC/ICC).
"We have devised a real-time sensing device, embedded within a contact lens case, which is capable of signaling the presence of abnormally high levels of live bacteria," said Nishal Govindji-Bhatt, Post-doctoral Research Associate at the University of Manchester. This technology has potential for use as a research tool in clinical studies to monitor levels of bacterial growth associated with contact lens wear, and as a new approach to reducing eye infection and the use of antibiotics.
"The aim of the study was to develop a sensor (Microbiosensor) embedded in the base of a contact lens case that changes color when a high level of bacteria is present," said Govindji-Bhatt. This would alert the contact lens wearer that they should not put the contact lens in their eyes.
The chosen tetrazolium dye, commonly called MTT, caused a color change when the bacterial level reached just over a million counts in 1 mL of solution within 8 hours. In tests, the Microbiosensor performance was not altered by the contact lens solution.
Contact lens cases should be kept clean and free from bacterial contamination, which can be achieved with the use of disinfectants (contact lens solution). "If this cleaning regime is not followed regularly and correctly, contact lenses can become covered in bacteria and when put into the eye it can cause severe eye infection and in rare cases, a loss of vision," said Govindji-Bhatt.
As part of the research, the sensor was fine-tuned with a range of chemical compounds called tetrazolium dyes, set in a semi-solid surface and embedded into contact lens cases. "We tested if a color change from yellow to dark blue would take place when harmful levels of bacteria were present, and ensured that the color change could be clearly seen by the user," said Govindji-Bhatt.
Govindji-Bhatt and Curtis Dobson, along with a team of researchers at the University of Manchester conducted this work with funding from the Biotechnology and Biological Sciences Research Council and Medical Research Council. Additional authors include Nicholas Goddard and Phil Morgan.