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Contact Lenses to track Blood sugar

Blood Glucose is a kind of sugar that is carried by the blood to all cells of the body in order to supply energy so that a human being can perform his/her daily tasks. But the glucose level in the blood needs to be maintained at a safe range in order to reduce the risk of heart diseases and diabetes. A condition in which the blood glucose level increases is known as Hyperglycemia. Common symptoms of hyperglycemia are dry mouth, increased thirst, fatigue, headaches, and blurred vision, etc.

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The blood glucose level in the body changes throughout the day, for example, after a meal, it rises and gets stabilized in an hour. To maintain blood glucose level within the safe range, one has to check his glucose level at regular intervals of time. Traditionally blood glucose level was monitored by Glucometers which comes with lancets or needles, a logbook to record results and test strips. To use this device, a patient needs to withdraw blood from the finger about five times a day and about 1800 times annually, these obligations create phobia in the patients. To overcome this problem, a contact lens has been designed which allows non-invasive monitoring of blood glucose level.

Canan Asli Yildirim’s new patent application WO2017116350A1 titled “A contact lens design sensing tear glucose level” discloses a non-invasive blood sugar level monitoring device i.e. Contact lenses with biosensors disposed within. The contact lens does not directly determine the blood sugar from the tears, rather it keeps monitoring the condition of hyperglycemia and signals the patient to draw blood samples only when it is needed.

According to another embodiment of the patent, the contact lens has embedded biosensors. These biosensors change color to signal high or low sugar levels in the blood. When the tear glucose level reaches approximately greater than 6,25-7.0 mg/dl, (blood glucose level > 125-140 mg/dl), a signal is provided with a color change between 380 – 720 nm and a color change occurs preferably at a linear scale proportional with the glucose concentration. This biosensor layer is applied on the surface of the lens or it can be embedded in the polymer material which can affect oxygen transmissivity of the product.

Figure 1 is the newly designed contact lens with metal particles. Boronic acid containing fluorophore/azobenzene dye which is positioned around the metal particles.

This new technology of contact lens may seem to be a small innovation, but its true value is understood by patients who don’t need to frequently prick their fingers in order to withdraw blood samples to know the condition of hypoglycemia (low blood sugar) or hyperglycemia (high blood sugar). What remains to see is what other innovations can we come up with to help patients.

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