Glaucoma treatment is aimed at the one modifiable variable known to change the outcome of the disease: intraocular pressure (IOP). Studies have shown that decreasing IOP reduces the likelihood of disease progression. The problem is that an IOP measurement is just a snapshot taken during the office exam and not necessarily representative of the IOP the patient might exhibit throughout the rest of the day and/or night. In the office, the IOP measurement is always taken with the patient in an erect position and during daytime office hours. Furthermore, we base our medical decisions on this snapshot value.
For example, we might be seeing hypothetical patient Jack Smith, who has a diagnosis of primary open-angle glaucoma with a pretreatment IOP of 25 mm Hg. Jack’s IOP has measured between 12 mm Hg and 15 mm Hg almost every time he has been seen over the past couple years. Nevertheless, and despite his IOP being on target for the level of damage evidenced, Jack presents with progression in clinical exam and on visual field testing as well as on OCT. It is possible that his IOP was rising above target every night, unbeknownst to him or his physicians. Without continuous IOP monitoring, there is no way to access that information.
CONTINUOUS IOP MONITORING
Continuous IOP monitoring promises to help clinicians better understand glaucoma as a disease and evaluate patient’s IOP fluctuations at baseline and in response to different medications and treatments.
In March 2016, Sensimed received FDA approval for the Triggerfish, a wearable 24-hour IOP monitoring system. The Triggerfish system consists of a soft silicone contact lens embedding a micro-sensor, an antenna that is taped around the patient’s eye, and a recorder that is usually worn around the neck. The Triggerfish records changes in eye volume, indirectly measuring IOP and producing IOP-related pattern curves. It can provide clinicians with a better, more realistic idea of the patient’s IOP over a period of 24 hours, with measurements taken during the day and night, while the patient is awake and asleep, and in an erect and supine position, as these are all physiologic changes normally occurring in a 24-hour period.
VIDEO | The Sensimed Triggerfish system for 24-hour IOP monitoring.
Sensimed has communicated that before the Triggerfish is actively commercialized, it intends to conduct a longitudinal study evaluating fast versus slow glaucoma progression. The company wishes to study ocular volume change as a separate measurement that could aid in the identification of glaucoma patients who are at higher risk of progression, a news release said.
FUTURE OUTLOOK
I firmly believe that we are turning a corner when it comes to improving our understanding of glaucoma and our capability to treat disease more efficiently. Between the new drug delivery systems in development and IOP-monitoring devices such as the Triggerfish, new doors will be opening very soon—I can’t wait!
