Glaucoma affects about 4 percent of the population over 40 years of age, and is an asymptomatic, progressive and irreversible disease which leads to blindness unless adequate treatment is provided early on. For those unlucky to have a severe form or remain undiagnosed, the disease takes a great on their vision and quality of life.
The disease is diagnosed by measuring intraocular pressure (IOP), a simple test performed by most opthamologists during office hours. However, these static measurements of IOP do not tell the full story of what is happening in the eye over time. A more effective test is to measure intraocular pressure dynamically, as this will correspond more closely to the risk of optic nerve damage. However, there has not been a cost-effective method to perform this measurement for most patients. Until now, that is.
Sensimed, a Swiss medical technology company, has released details of a continuous IOP monitoring platform that uses a soft, disposable contact lens containing a pressure sensor and are recruiting patients for a trial in the United States. The device is already marketed in Europe. There are four key components of the telemetric pressure measuring system, which they call Triggerfish™:
- A micro-electronic mechanical system sensor (MEMS) and a telemetry microprocessor are embedded in a soft, hydrophilic, disposable soft contact lens. All sensor elements are embedded in the lens outside the patients line of sight. MEMS devices are microscopic electronic devices that can detect tiny movements and are the basis of the accelerometers and gyroscopes built into most smartphones.
Antenna & Data Cable:
- A circular antenna is taped around the eye which sends energy and receives info and is connected to the portable controller (see diagram below)
- A battery powered recorder stores measurements and wirelessly uploads to opthamologist’s desktop application
- Data analysis and bioinformatics software on the opthamologist’s computer.
The company is soliciting patients diagnosed with primary open angle glaucoma (POAG) for a San Diego-based clinical trial to assess the safety and effectiveness of the Triggerfish device in recording of relative fluctuation in IOP.
In a recent uncontrolled trial of the Triggerfish platform published in the Journal of Glaucoma (1) this past May, ten healthy volunteers wore the system for a 24 hour period, with assessments of best-corrected visual acuity, surface wetting ability, and mobility of the Sensor were assessed after 5 and 30 minutes, 4, 12 and 24 hours.
Subjective wearing comfort was scored by users and activities documented in a notebook. Subject comfort scored high and did not fluctuate significantly over time. Best-corrected visual acuity was significantly reduced during sensor wear. Three subjects developed a mild, transient corneal abrasion. In all but one patient the Triggerfish device obtained usable data of a telemetric signal recording with sufficient sensitivity to depict ocular pulsation.
Sensimed is based in Lausanne, Switzerland and has been marketing its device in Europe since it was approved by regulators there in 2009. Triggerfish is still pending FDA approval.
(1) De Smedt, Stefan MD; Mermoud, André MD; Schnyder, Corinne MD. “24-hour Intraocular Pressure Fluctuation Monitoring Using an Ocular Telemetry Sensor: Tolerability and Functionality in Healthy Subjects”. Journal of Glaucoma. May 11 2011.