Preliminary study on implantable inductive-type sensor for continuous monitoring of intraocular pressure

    loading  Checking for direct PDF access through Ovid

Abstract

Background

This study aims to validate the performance and biocompatibility of an implantable inductive-type sensor for continuous monitoring of intraocular pressure (IOP)

Methods

The sensor is composed of a top layer integrated with an inductor and capacitor circuit, and a bottom layer integrated with ferrite. With IOP change, the sensor's bottom layer is mechanically deflected, which changes the distance between the bottom-layer ferrite and top-layer inductor, resulting in an alteration of inductance magnitude and the resonant frequency (RF). In-vitro measurement was conducted via air pressurization in a sealing jig (n = 3). Subsequently, the sensor was implanted into the anterior chamber of a rabbit eye. In-vivo measurement was performed while the IOP was elevated by infusion of balanced salt solution (BSS, 6 μL/min). Smaller-sized sensors later were implanted into two rabbit eyes, which were microscopically examined at 2, 4 and 8 weeks post-implantation. The eyes were then immediately enucleated for histological examination.

Results

The in-vitro measurement showed a significant RF shift as pressure in the jig was increased from 0 mmHg to 60 mmHg (average initial frequency: 10.86 MHz, average shift: 403 kHz). The in-vivo measurement also showed an RF decrease, from 12.80 MHz to 12.67 MHz, as the pressure was increased from 10 mmHg to 20 mmHg. Microscopic in-vivo evaluations and histological exams, performed at intervals up to 8 weeks post-implantation, showed no evidence of significant inflammation or deformity of the ocular-tissue structures.

Conclusions

The implantable inductive-type IOP sensor demonstrated wireless pressure-sensing ability and favourable biocompatibility in the rabbit eye.

Related Topics

    loading  Loading Related Articles