Glaucoma occurs when the optic nerve becomes damaged, usually by a build-up of fluid in the front part of the eye which causes intra-ocular pressure (IOP).
Glaucoma effects around 70 million people globally and is often identified during routine eye tests, by which time lasting damage may already have been caused.
The new contact lenses contain micro-sensors which monitor changes in IOP over a period of several hours, sending the data collected wirelessly so it can be analysed by an ophthalmologist.
The research has been carried out by Professor Hamdi Torun, of Northumbria University; and Professors Günhan Dündar and Arda D. Yalcinkaya, of Boğaziçi University, in Istanbul. Their work, detailed in a paper published in Contact Lens and Anterior Eye, set out the findings from their initial pilot study with six participants.
Having determined that the technology works, they now plan to carry out a further study with a larger group of participants, which will take place over the next year. The lenses will then be made commercially available through their spin-off company GlakoLens.
According to the team, one benefit of using the GlakoLens contact lenses is that measurements can be taken more easily over a longer period of time, giving a more accurate diagnosis.
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In a statement, Professor Torun said: “IOP can vary greatly over a 24-hour period, so it is important to monitor the patient either at intervals or ideally continuously for a whole day to get the best insight into the health of their eyes.
“Traditional methods for measuring IOP involve initially going to a clinic for a single measurement in a day, the result of which can be misleading due to the natural variation of IOP.
“If a variation is detected, further investigation is then needed which requires hospitalisation for a whole day, during which repeated measurements are taken using a technique called Goldmann applanation tonometry, which involves numbing the eye with drops and then using a small cone to touch the cornea to measure the pressure.
“However, studies have shown that waking patients up at night to carry out measurements can make the results less accurate, in addition to obvious discomfort to the patients and the economic cost to the healthcare system.
“The benefit of the contact lenses we have developed is that once placed in the eye, the patient can then go about their day as normal while their IOP measurements are recorded and sent to a doctor for analysis once the 24-hour period of testing is complete.”
The new system has been tested with six healthy volunteers, during which time they were asked to drink 1.5 litres of water and lie flat to intentionally increase their IOP levels.
Previous products to measure IOP have used an electrically active silicon chip, which results in a thicker, less comfortable lens. The chip also makes the lens less flexible and can restrict vision, making it more difficult to carry out daily activities.
The GlakoLens contact lenses use an electrically passive sensor embedded in a disposable soft contact lens, and a wearable electronic readout system to collect, store and process the data.
As well as diagnosing glaucoma, the team said there is potential for the lenses to be used to detect other health conditions by measuring glucose, lactic acid and other molecules in the eye.
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