Using sensors to estimate intraocular pressure: a review of intraocular pressure telemetry in clinical practice

ABSTRACT

Introduction: If intraocular pressure (IOP) is the sole modifiable risk factor for glaucoma progression, glaucoma management should not rely on a vague estimation of its value measured over seconds, out of the 31,536,000 seconds in a year. A technology that would allow continuous and accurate IOP measurement in any situation could drastically enhance the diagnosis, treatment, follow-up and advice we give glaucoma patients.

Areas covered: This review covers the development history of IOP telemetry devices, from Green and Gilman’s first 24-hour telemetry concept in 1974 to the two devices commercially available today: Sensimed’s TriggerFish contact lens sensor and Implandata’s implantable monitoring device. Through a systematic review of the articles indexed by the US National Library of Medicine National Institute of Health between November 1969 and July 2019 with the keywords ‘telemetry’, ‘continuous iop’ and ‘24 hour iop’, it details the ongoing contribution of telemetry to glaucoma knowledge.

Expert opinion: The usage and purpose of the currently available telemetry devices remain specific and targeted. However, we foresee that this is likely to change in the upcoming years, with the advent of new, more versatile devices and ergonomic modules. The future of telemetry may lie in miniaturization, connectivity and new organic measures.

KEYWORDS:

• Glaucoma
• 24 h
• continuous
• IOP
• monitoring
• TriggerFish
• EyeMate
• ARGOS
• contact lens sensor
• implantable

Article highlights

• Intraocular pressure was shown to be extremely dynamic with both short- and long-term physiological and environmentally-induced fluctuations.

• Recent studies suggested that intraocular pressure variations, including nocturnal pressure spikes, could have a direct impact on glaucoma progression, regardless of absolute pressure values.

• Filtering surgery and successful selective laser trabeculoplasty treatments were shown to reduce the amplitude of intraocular pressure variations.

• Sensimed’s TriggerFish contact lens sensors measure ocular soft tissues’ strain. As such, the results are presented in an arbitrary unit and not in millimeters of mercury, but may present a unique clinical interest by reflecting the reaction of ocular tissues.

• As of today, two very different but equally promising telemetry devices exist to achieve continuous IOP monitoring: both of them have proven their safety profile and accuracy, but rather than being rivals, their clinical indications complement one another.

• The future of telemetry may lie in miniaturisation (minimally-invasive, foldable or injectable devices), connectivity (to automated adjustable drainage devices) and new organic measures (beyond pure absolute pressure values).

Declaration of interest

K. Mansouri has received fees from Topcon, Alcon, Allergan, Optovue and acts as a consultant for Santen, Sensimed, ImplanData. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This paper was not funded.