Glaucoma affects around 70 million individuals worldwide and can cause permanent loss of vision if not treated, but around half of those living with the condition are not aware of it.
Generally developing slowly over time, many cases of glaucoma are noticed during routine eye tests, by which time lasting damage may already have been caused.
But this could change in the future as academics from the UK and Türkiye have developed a contact lens that can detect changes in eye pressure which signal possible glaucoma.
Glaucoma happens when the optic nerve, which connects the eye to the brain, becomes damaged, generally by a build-up of fluid in the front part of the eye which increases pressure inside the eye and is known as intra-ocular pressure (IOP).
The new contact lenses contain micro-sensors that monitor changes in IOP over several hours, sending the data collected wirelessly so it can be examined by an ophthalmologist and a diagnosis given.
The research has been carried out by Professor Hamdi Torun, of North Umbria University; and Professors Günhan Dündar and Arda D. Yalcin kaya, of Boğaziçi University, in Istanbul, and has been published in Contact Lens and Anterior Eye, the official Journal of the British Contact Lens Association.
Having determined that the technology works successfully, they plan to conduct a further study with a larger group of participants, which will take place over the next year. The lenses will be available commercially through their spin-off company GlakoLens.
One of the benefits of using the GlakoLens contact lenses to diagnose glaucoma instead of carrying out a traditional examination is that measurements can be taken more easily over a longer period, giving a more exact diagnosis.
Intra-ocular pressure, or IOP, can differ greatly over a 24-hours, so it is important to observe 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, which can be misleading due to the natural variation of IOP.
If a variation is noticed, further investigation is then needed which requires hospitalization 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.
Though, studies have shown that waking patients at night to carry out measurements can make the results less precise, in addition to obvious worry to the patients and the economic cost to the healthcare system.
The advantage of the contact lenses we have developed is that once positioned in the eye, the patient can go about as normal, while their IOP measurements are recorded and sent to a doctor for investigation once the 24-hour period of testing is complete, says Professor Hamdi Torun, of North Umbria University
The new system has been tested with six healthy volunteers, during which time they were asked to drink 1.5 liters of water and lie flat to intentionally increase their IOP levels.
While this is not the first time contact lenses have been developed to measure IOP, earlier products have used an electrically active silicon chip, which results in a thicker and less comfortable lens. The chip also makes the lens less flexible and can limit vision, which makes it more difficult to carry out day-to-day activities.
The GlakoLens contact lenses use an electrically passive sensor which is fixed in a disposable soft contact lens and a wearable electronic readout system to store, collect, and process data– making the lens more comfortable and letting the patient go about their day as normal.
As well as diagnosing glaucoma, there is also potential for the lenses to be used to detect other health conditions by measuring glucose, lactic acid, and other molecules present in the eye.
As Professor Torun says, we believe this technology has huge potential and could not only save the sight of patients in the early stages of glaucoma but also provide early diagnosis of other diseases in the future.
