Triggerfish: Smart Contact Lens for Glaucoma Monitoring

Last month, the FDA (US Food and Drug Administration) granted a marketing license to a Swiss-based company called Sensimed for its smart contact lens that aims to tackle current limitations in monitoring intraocular pressure (IOP) in patients with glaucoma.

This sensor device is currently being utilized throughout Europe and has been studied in the US, but will hopefully start to be more widely available to practitioners and patients shortly for glaucoma monitoring.

Current Glaucoma Statistics

Glaucoma is the second leading cause of blindness in the world according to the World Health Organization (WHO). It is estimated that over 3 million Americans currently have glaucoma, but only approximately half of those know that they have it. In the US, more than 120,000 people are blind from glaucoma. 

These statistics are due mainly to the fact that there are virtually no symptoms associated with primary open angle glaucoma until the disease has entered the advanced stages. There is usually no pain and no noticeable vision loss; therefore, many people may go many years without proper diagnosis and treatment of this condition. Once optic nerve damage and vision loss has occurred, it cannot be regained. The goal of treatment for glaucoma is to prevent or slow the progression of the disease as much as possible, but even with proper medication and surgery, there is still a subset of the population who will continue to experience vision loss. 

The Role of Intraocular Pressure (IOP)

Although intraocular pressure is only one factor that plays into the diagnosis and management of glaucoma, it is typically one of the most important ways that we as eye care practitioners manage and monitor our glaucoma patients. We use IOP to gauge the effectiveness of the medications that we prescribe, or to determine the benefit of a surgical or laser procedure. We typically set a target pressure for our patients based on what we believe the IOP needs to stay below to prevent further damage, and we adjust the target pressure based on visual field and imaging studies. 

As described, IOP is an extremely important component in managing glaucoma, however there are limitations to this measurement. We all know that IOP varies throughout the day and has peaks and troughs that are related to our activities and circadian rhythm, but we are currently only able to measure IOP in our office at a single point in time. This is not ideal as there is so much more valuable information related to IOP that we are currently unable to obtain. 

Sensimed Triggerfish Smart Contact Lens

Wouldn’t it be great if there was a way to constantly monitor IOP throughout the day and night without the patient having to come into your office? The Sensimed Triggerfish device is a disposable soft silicone contact lens that has a sensor imbedded within the material. The contact lens is worn for a maximum of 24 hours and transmits data wirelessly from the sensor to an adhesive antennae worn around the eye. The patient also wears a portable data recorder that receives information from the antennae and can transfer the data via Bluetooth to the eye care practitioner's computer. The lens measures for 30 seconds every 5 minutes and readings taken during blinks and other noise are filtered out, leaving 288 readings for a 24-hour period. This gives us 288 readings rather than the 1 that glaucoma patients traditionally have taken!

One very important item to consider is that the Triggerfish device does not actually directly measure and record intraocular pressure, the sensor measures changes in the surface of the eye that correlate with IOP. There is not currently any reliable method of translating the output of the gauge to the actual IOP, but the measurements do produce a graph that can accurately portray the intraocular pressure fluctuation over time. This is still very useful information. If you think about it, the specific number doesn’t particularly matter as there is no definite introacular pressure in which damage does or does not occur; information about spikes or the lack thereof is more valuable in many cases. 

We’ve all heard about this technology being studied, but it now seems as though we are getting closer and closer to having it available to our patients! 

-Dr. Dexter