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Jeong Oen Lee, Juan Du, Haeri Park, Mehmet Sencan, Max Kudisch, David Sretavan, Hyuck Choo; In Vivo Intraocular Pressure Measurements Using A Miniaturized Nano-Photonic Sensor Implant. Invest. Ophthalmol. Vis. Sci. 2016;57(12):6462.
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© ARVO (1962-2015); The Authors (2016-present)
We have been developing a nanophotonic pressure sensor whose optical resonance is directly related to intraocular pressure (IOP). Bench testing has demonstrated sensor near-infrared (NIR) reflectance to accurately track pressures from 0-50 mmHg. The current study examined sensor performance following implantation into rabbit eyes for up to one month.
The nanophotonic IOP sensor is a micro-/nano-fabricated 800-micron-diameter silicon microcavity flanked on one side by a flexible silicon-nitride membrane embedded with reflective gold nanodots. Sensors were attached to acrylic intraocular lenses (IOL) and implanted into the eyes of New Zealand White rabbits following lens phacoemulsification. Sensor-resonance signatures carrying IOP information were obtained 2 inches away from the eye right after sensor implantation, and at 2 & 4 weeks. Measurements were also made before and after IOP elevation by intraocular saline injection. TonoVet IOP measurements were made in parallel in all cases for comparison.
In-vivo sensor measurements exhibited excellent signal-to-noise (SNR) ratio of 13 dB at all time points. Sensor-derived IOPs ranged from 6.8 to 7.1 mmHg at 2 and 4 weeks. Concurrent TonoVet IOPs matched all sensor IOPs but were consistently 0.5-3 mmHg higher. Intraocular saline injection right after implantation caused sensor-IOP readings to go from 7.0 to 20.0 mmHg.
A miniaturized nanophotonics-IOP sensor using NIR light as a sensing medium provides in-vivo IOP measurements in rabbits for at least 1 month after implantation. The sensors exhibited good SNR ratio, stability, and tracking of IOP increases.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
Figure 1. (A-D) The 800-micron IOP sensor mounted on an IOL and folded for ocular insertion; arrow in A points to nanodot array reflection; and (E) The sensor (arrow) in a rabbit eye. (F) In-vivo measurement on anesthetized rabbit; (G) In-vivo optical resonance signatures before and after saline injection.
Figure 3. (A) Sensor-derived IOP after saline injection increased from 7.0 to 20.0 mmHg; (B) and (C) sensor-derived IOPs from a sensor at 2 & 4 weeks, compared with TonoVet measurements before and after sedation.
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