‘Futuristic’ contact lens gains FDA marketing approval

Tonometry on a contact lens? Not quite, but close.

Recently green-lighted for stateside marketing by the U.S. Food and Drug Administration (FDA), a novel, hi-tech contact lens provides clinicians' continuous, 24-hour ocular measurements that may help identify the best time of day to measure glaucoma patients' intraocular pressure (IOP).

Known as the Sensimed Triggerfish, this sensor-laded, soft silicone contact lens collects minute measurements of patients' eye volume, transmitting the data wirelessly through an adhesive antenna and data-recorder apparatus directly to the clinician's computer. The device shows the range of time throughout the day when eye pressure may be increasing, according to an FDA news release, but does not actually measure IOP.

Glaucoma, the second leading cause of blindness in the U.S., is a group of eye disorders leading to progressive damage of the optic nerve. This damage leads to irreversible vision loss, often with no advanced warning. Glaucoma currently cannot be prevented, but early diagnosis and treatment can keep it controlled, making IOP a critical measurement.

Elevated IOP is the main risk factor for glaucoma; however, IOP varies throughout the day and may not be abnormally high when the patient presents for an eye exam. Tonometry takes a snapshot of IOP at the time, but diurnal variations can yield higher results as IOP tends to increase as patients lay and rest, notes Thomas Quinn, O.D., AOA Contact Lens and Cornea Section past-chair, in a previous interview with AOA Focus. The Triggerfish's continuous monitoring feature ensures clinicians are measuring IOP at the correct time.

Noting a 2010 study in this area, Dr. Quinn says biosensors embedded in a contact lens proved a viable method of measuring IOP, though the trial lens proved bulky and uncomfortable for the average patient.

"There are some real basic considerations that can't be overlooked—a patient can't wear a contact lens that's three times bigger, for instance—as we get excited about this new technology," Dr. Quinn said. However, that's a problem potentially remedied in this latest device, as the FDA notes supporting clinical data includes studies on the tolerability of the contact lens.

Contact lenses of the future, today

AOA Focustook a look into the near future of contact lens technology with the award-winning feature article, Get smart: Contact lenses of the future, today, in which Dr. Quinn continued his discussion about the role of contact lens technology in glaucoma care. Excerpted from the feature article:

• Advances (in contact lens technology) could prove promising for glaucoma patients, relegated to daily medications to alleviate intraocular pressure, often via prescription eye drops they personally administer. And therein lies the rub: Patient compliance with regard to self-administered drops is far from perfect.
• According to a 2008 study in the Canadian Journal of Ophthalmology, of 500 glaucoma patients tracked, about 25% reported missing one eye drop weekly, mainly due to forgetfulness and lack of proximity to drops. Furthermore, almost 7% reported missing their eye when administering drops, and about 34% demonstrated improper technique.
• Drug-eluting lenses could help with much of that. Dr. Quinn says, for example, drug concentration spikes in the tear film after drop placement, but declines with each blink and may reach a period with no effective medication action occurring.
• "It goes up and down, but if we had it delivered through a contact lens, it would allow for a steady stream of delivery—a continuous therapy—that will end up with happier, healthier eyes, more quickly," Dr. Quinn says.

Reading more about hi-tech contact lenses in the July/August 2014 edition of AOA Focus.