How might continuous IOP monitoring change glaucoma management?
by Noelle Lake, MD
The SENSIMED Triggerfish® and other “smart” contact lenses in development estimate intraocular pressure (IOP) continuously over the course of 24 hours, providing the clinician with a wealth of information that was previously unavailable. IOP-sensing contact lenses represent a tectonic shift in the evolution of IOP monitoring and glaucoma management. Where once there was a snapshot, or a series of snapshots, now there is a feature-length movie.
Now that FDA has given marketing clearance to the SENSIMED Triggerfish®, the question remains of how to understand and utilize all this newly amassable IOP data. What findings or patterns will be clinically meaningful? How might this surplus of information be distilled into benefits for patients?
A recently published trial by researchers at Columbia University Medical Center is helping to snap into place a few puzzle pieces around IOP-sensing contact lenses.1 We caught up with lead author C. Gustavo De Moraes, MD, MPH, to ask what this study means for clinicians and how it might shape the future of glaucoma care.
EVOF: You used contact lens-sensing technology to identify novel correlates of faster-than-average visual field loss among patients being treated for glaucoma. What findings from your study most intrigued you?
Dr. De Moraes: The most intriguing findings were, first, that a single 24-hour recording with the contact lens sensor (CLS) can differentiate fast from non- or slow progressors; and second, that such recording had a better predictive ability than multiple, snapshot IOP measurements obtained from conventional tonometry.
EVOF: The medical community needs a way to refer to this new metric derived from contact lens-sensing devices. Terms such as “IOP-related profiles,” “ocular dimension changes,” “IOP-related parameters,” “24-hour CLS-output curves,” “patterns,” and “signatures” have surfaced to describe these outputs. What would you propose as a name for these outputs?
Dr. De Moraes: For now, I prefer calling them “CLS-output curves.” Numerous published studies support a strong correlation between these recordings and conventional applanation tonometry. However, it is possible that these signals are depicting more than just an IOP-related parameter; they could also be reflecting the elasticity and compliance of ocular tissues and how they respond to IOP, which is a much broader concept. This could help explain, for example, why some eyes progress despite low IOP, while others with high IOP remain stable. How the ocular dimensions respond to changes in volume could give us insight into the eye’s susceptibility to IOP insult.
EVOF: Looking ahead, perhaps 3 to 5 years from now, how do you foresee contact lens sensors being used in the diagnosis and monitoring of patients with glaucoma?
Dr. De Moraes: I believe they can potentially be useful to monitor glaucoma patients, particularly for risk stratification (as suggested in our article) and comparing changes in treatment. For instance, does adding/advancing treatment (eg, eye drops, laser, or surgery) improve the CLS-output curves compared to previous therapy?
EVOF: What about the prospect of linking anti-glaucoma drug delivery directly to an IOP-approximating contact lens?
Dr. De Moraes: This has been the topic of recent research, some of which has shown promising results. If successful, a contact lens drug-delivery system could improve patient compliance to treatment compared to eye drops.
REFERENCE
De Moraes CG, Jasien JV, Simon-Zoula S, et al. Visual field change and 24-Hour IOP-related profile with a contact lens sensor in treated glaucoma patients. Ophthalmology. 2015 Dec 30.