Google has come up with another wearable eye device, this time a lens made out of soft contact material that might help diabetes patients keep track of their glucose levels.
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The company revealed a functional prototype Jan. 16 that doctors are saying has the potential to replace not only the current continuous glucose monitors implanted under the skin, but perhaps one day even the painful finger-pricking blood tests.
The so-called smart lens, a tiny wireless computer chip that contains a glucose sensor and an antenna thinner than a strand of hair, is implanted between soft contact lens material, which is worn on the surface of the eye. The lens is powered by tapping into radio waves in the air and is designed to send data to a smart phone or other device.
"Glucose levels change frequently with normal activity like exercising or eating or even sweating. Sudden spikes or precipitous drops are dangerous and not uncommon, requiring round-the-clock monitoring," say Google [x] co-founders Brian Otis and Babak Parviz in a statement sent to ABCNews.com.
"Although some people wear glucose monitors with a glucose sensor embedded under their skin, all people with diabetes must still prick their finger and test drops of blood throughout the day. It's disruptive, and it's painful. And, as a result, many people with diabetes check their blood glucose less often than they should."
"At Google[x], we wondered if miniaturized electronics — think: chips and sensors so small they look like bits of glitter, and an antenna thinner than a human hair — might be a way to crack the mystery of tear glucose and measure it with greater accuracy."
The gold standard for testing the presence of glucose is doing a quick blood test. But traces of glucose can also be found in bodily fluids under the skin and in the eyes.
But because changes in glucose levels can be so abrupt, there may be a lag time in detection in the eyes, according to endocrinologists consulted by ABCNews.com.
The company said these are "early days" in its research. More would need to be known about the correlation between tear and blood glucose and what the lag time is in detection, as well as how the environment, such as heat and wind, can affect tears.
Dr. Gerald Bernstein, director of the Friedman Diabetes Institute at Beth Israel Medical Center in New York City, said the idea is "terrific, if it can be done." The key is whether the device measures just the tears on the outside of the eye or the aqueous humor, the thin, watery fluid that fills the space between the cornea and the iris.
Aqueous fluid is "a more predictable reflection of the blood sugar," he said. "And don't forget, this is bodily fluid and not exactly what is in the blood."
The concept is not new, according to Bernstein. Several years ago, he consulted with an Albuquerque, N.M., company to measure glucose in the aqueous humor.
"They found that they were able to have a statistically significant correlation [with blood glucose]," he said.
Those scientists used a low-level laser that could safely send light through the fluid in the front chamber of the eye to record the blood sugar. It was used for patients undergoing surgery so doctors could continuously read blood sugar levels.
"It's not an easy thing to do," Bernstein said of the Google [x] device. "Do I think this is the ultimate answer? Probably not. But I do think it's something worth pursuing. It is a lot more convenient than the current continuous monitor, which does the same thing."
An estimated 3 million Americans have type 1 diabetes, according to the The American Diabetes Association. It is usually diagnosed in children and young adults, and was previously known as juvenile diabetes.
In this form of diabetes, the body does not produce insulin, the hormone that is needed to convert sugar, starches and other food into energy.
"It's one of those things that get a lot of attention," Dr. Alvin C. Powers, director of the Vanderbilt Diabetes Center in Nashville, said of the Google [x] lens.
"Ninety-nine percent of people with diabetes don't use a subcutaneous sensor," he said. "Those people are pricking their finger [to measure glucose in the blood] because a device under the skin is very expensive and has to be calibrated on a regular basis. The same would be true of the contact lens approach – you would have to have it calibrated to make sure it was meaningful."
One of the advantages of the eye fluid monitor is that it provides a continuous reading, "as opposed to a prick, which only tells you what it is when you prick," said Powers. "Blood glucose is labile and changes in a matter of minutes."
The subcutaneous device is implanted under the skin with a needle.
"It's not as easy as putting it in a contact lens," he said. A smart lens could perhaps equilibrate quickly -- "not seconds, but probably minutes ... and it could potentially be faster than subcutaneous glucose."
But blood glucose can rise or fall quickly, said Powers, and "just how faithfully [a smart lens] does that when there is a blood glucose change, that has to be worked out."
"[Google] would have to prove that the eye fluid would equilibrate with the blood and have the same dynamic," he said. "But it's too early to tell if one is better than the other."
And, he cautioned, there is "more than a little work to be done" before the Google [x] lens can be used clinically. "There are still a number of issues using the glucose sensors and adapting them. It will take some validation studies."