Intraocular Pressure Monitoring Sensors

Katuri, Kalyan C.; Asrani, Sanjay; Ramasubramanian, Melur K.

doi:10.1109/jsen.2007.912539

Cited by 86 publications

(44 citation statements)

References 55 publications

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“…Passive telemetric sensing has been widely used as one of the viable methods to accomplish continuous and accurate non-contact IOP measurements of glaucoma patients [1,2]. It enables straightforward IOP sensing by utilizing a transensor implant that registers environmental pressure variations inside the eye, so that the IOP can be directly measured by using an external reader wirelessly interrogating the implant.…”

Section: Introductionmentioning

confidence: 99%

Implantable Flexible-Coiled Wireless Intraocular Pressure Sensor

Chen

Saati

Varma

et al. 2009

2009 IEEE 22nd International Conference on Micro Electro Mechanical Systems

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This work presents an implantable wireless passive pressure sensor for long-range continuous intraocular pressure (IOP) monitoring of glaucoma patients. The sensor is microfabricated with use of parylene C (polychloro-p-xylylene) to create a flexible coil substrate that can be folded during implantation for suture-less minimally invasive surgery, while stretched back without damage for enhanced inductive sensor-reader coil coupling and the corresponding sensing signal. Extensive device characterizations including on-bench testing and in vivo and ex vivo animal studies verify the device feasibility in both engineering (1 mmHg pressure sensing accuracy and 2 cm sensing distance) and surgical (robust fixation to the iris and long-term biocompatibility in the intraocular environment) aspects, all meeting specifications for future practical implementation of such IOP sensing technology.

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Section: Introductionmentioning

confidence: 99%

Implantable Flexible-Coiled Wireless Intraocular Pressure Sensor

Chen

Saati

Varma

et al. 2009

2009 IEEE 22nd International Conference on Micro Electro Mechanical Systems

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“…Telemetric sensing is one of the viable methods to accomplish continuous and faithful noncontact IOP measurements [5], [6]. It utilizes a transensor implant that registers environmental pressure variations inside the eye so that the IOP can be directly measured by using an external reader wirelessly interrogating the implant.…”

mentioning

confidence: 99%

“…However, despite successful wireless pressure sensing demonstration, the sensing distance of the entire sensor-reader system in the previous work was not sufficient in practice. Such challenge can also be found in other works with considering size and other constraints [6]. As a result of further improvement, this work focuses on a different sensor design for electromagnetic coil coupling and resonance quality factor enhancements, followed by a new readout method for noise reduction and signal-to-noise ratio (SNR) enhancement in actual wireless measurements [20].…”

mentioning

confidence: 99%

Wireless Intraocular Pressure Sensing Using Microfabricated Minimally Invasive Flexible-Coiled LC Sensor Implant

Chen

Saati

Varma

et al. 2010

J. Microelectromech. Syst.

245

130

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Abstract-This paper presents an implant-based wireless pressure sensing paradigm for long-range continuous intraocular pressure (IOP) monitoring of glaucoma patients. An implantable parylene-based pressure sensor has been developed, featuring an electrical LC-tank resonant circuit for passive wireless sensing without power consumption on the implanted site. The sensor is microfabricated with the use of parylene C (poly-chlorop-xylylene) to create a flexible coil substrate that can be folded for smaller physical form factor so as to achieve minimally invasive implantation, while stretched back without damage for enhanced inductive sensor-reader coil coupling so as to achieve strong sensing signal. A data-processed external readout method has also been developed to support pressure measurements. By incorporating the LC sensor and the readout method, wireless pressure sensing with 1-mmHg resolution in longer than 2-cm distance is successfully demonstrated. Other than extensive on-bench characterization, device testing through six-month chronic in vivo and acute ex vivo animal studies has verified the feasibility and efficacy of the sensor implant in the surgical aspect, including robust fixation and long-term biocompatibility in the intraocular environment. With meeting specifications of practical wireless pressure sensing and further reader development, this sensing methodology is promising for continuous, convenient, direct, and faithful IOP monitoring.[ 2009-0111]Index Terms-Implantable microdevice, intraocular pressure (IOP), LC pressure sensor, parylene, wireless sensing.

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“…Such measurements can only be obtained for up to 24 h because of side complications that accompany long-term use [41][42][43] . To overcome the aforementioned limitations, implants based on radio-frequency (RF) technologies have been used to monitor endovascular pressure 44 , intracranial pressure (ICP) 45,46 , and IOP [47][48][49][50][51][52][53][54][55][56][57][58] . The typical size of these implants ranges from a millimeter to a few centimetres.…”

Section: Introductionmentioning

confidence: 99%

A microscale optical implant for continuous in vivo monitoring of intraocular pressure

Lee

Park

et al. 2017

Microsyst Nanoeng

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Intraocular pressure (IOP) is a key clinical parameter in glaucoma management. However, despite the potential utility of daily measurements of IOP in the context of disease management, the necessary tools are currently lacking, and IOP is typically measured only a few times a year. Here we report on a microscale implantable sensor that could provide convenient, accurate, ondemand IOP monitoring in the home environment. When excited by broadband near-infrared (NIR) light from a tungsten bulb, the sensor's optical cavity reflects a pressure-dependent resonance signature that can be converted to IOP. NIR light is minimally absorbed by tissue and is not perceived visually. The sensor's nanodot-enhanced cavity allows for a 3-5 cm readout distance with an average accuracy of 0.29 mm Hg over the range of 0-40 mm Hg. Sensors were mounted onto intraocular lenses or silicone haptics and secured inside the anterior chamber in New Zealand white rabbits. Implanted sensors provided continuous in vivo tracking of short-term transient IOP elevations and provided continuous measurements of IOP for up to 4.5 months.

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Intraocular Pressure Monitoring Sensors

Cited by 86 publications

References 55 publications

Implantable Flexible-Coiled Wireless Intraocular Pressure Sensor

Implantable Flexible-Coiled Wireless Intraocular Pressure Sensor

Wireless Intraocular Pressure Sensing Using Microfabricated Minimally Invasive Flexible-Coiled LC Sensor Implant

A microscale optical implant for continuous in vivo monitoring of intraocular pressure

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