Advances in telemetric continuous intraocular pressure assessment

With an ageing population showing an increasing prevalence of glaucoma, there is a pressing demand for continuous intraocular pressure (IOP) measurements which could surpass clinic-based measurements such as routine applanation tonometry. Glaucoma patients have fluctuations in IOP, and it has been proposed that these fluctuations are relevant to glaucoma progression. In addition, interindividual and intraindividual variation in corneal thickness and rigidity can lead to significant and poorly quantitated errors in applanation-based methods of estimating IOP. Microelectrical mechanical systems and complementary metal oxide semiconductor-based technology has enabled the development of smart miniaturised devices by augmenting the computational ability of microelectronics with capabilities of microsensors and microactuators. This review addresses various sensor technologies and both invasive and non-invasive approaches to the measurement of IOP. Advances in wireless communication (telemetry) between the implanted sensors and the external readout device are reviewed. In addition, biocompatibility of implantable sensors is discussed.