Photo by: Cobrakarin
As it is with so many innovations, the idea for contact lenses can be traced back to the great Leonardo da Vinci. He was, as usual, way ahead of his time: Although Leonardo conceived of contact lenses in the 1500s, they weren’t commercially developed for several hundred more years.
Leonardo’s idea certainly caught on: According to recent estimates, contact lenses are worn by 135 million people around the world—a figure that includes more than 35 million Americans.
Their primary use is, of course, to enhance vision, but they are worn for several other reasons. One is aesthetic. Although it seems to be “cooler” now than at any time in recent history to wear glasses—thank you Bono and Tina Fey—millions of people don’t want anything to do with them. Contact lenses also have other benefits—they don’t steam up, they aren’t affected by wet weather and they offer users a wider field of vision than glasses.
For years, researchers have been eyeing other uses for contact lenses, with one of the most promising being drug delivery. Eye drops are the most frequently used mechanism for delivering drugs to the eye, but they are inherently inefficient: either our tears wash away most of the medicine before it can be absorbed or it ends up in a tissue. In addition, some eye-drop regimens are very challenging, requiring administration several times a day. It is very easy for patients, especially elderly ones, to simply forget to take their medicine.
So, researchers are looking into whether or not drugs designed to treat eye disease can be delivered via contact lenses instead of drops—a method that could be very efficient, and one that would free patients from have to remember to dose themselves.
Work to develop contact lenses that function as efficient drug-delivery vehicles is underway on several fronts. One promising effort was described in a recent article in Medill Reports, which is published by Northwestern University. The article profiles a Harvard Medical School team that since 2007 has been developing a contact lens to deliver antibiotics to the eye.
The Harvard team’s mission was “to design a lens that was comfortable, compatible with the body and deliver a constant amount of medicine.” The solution it came up with sounds pretty sophisticated: “a biodegradable dual-polymer delivery system within a lens built from pHEMA, the plastic material used in manufacturing today’s lenses.”
To test its invention, the team infused the lens with a common antibiotic and dropped it rather ominous-sounding solution “teeming with staph bacteria recovered from patients with cornea, eyelid and tear-duct infections.” The results were promising: “The contact successfully released its medicine at a constant rate, sometimes for as long as 100 days, and cleared the infection.”
The article goes on to discuss other potential uses for contact lenses that sound as though they sprang from the mind of an over-caffeinated science fiction writer, including serving as “bionic eyes” and monitoring blood pressure or insulin. Amazing ideas worthy of Leonardo da Vinci himself.
