A soft contact lens with a MEMS strain gage embedded for intraocular pressure monitoring

We propose a novel approach to intraocular pressure (IOP) measurement allowing minimal invasive continuous monitoring over prolonged periods, regardless of patient position and activities. The key element of this innovative measurement method is a soft contact lens with a microfabricated strain gage embedded allowing the measurement of the cornea curvature deformation due to IOP changes. Tests on a eye-simulating device have shown that the sensor is capable of monitoring continuously a deformation of cornea radius inferior to 0.0055 mm, which corresponds to a sensitivity of better than 2 mmHg IOP, according to an in vitro and an in vivo studies about the correlation between IOP and corneal curvature in human beings.

INTRODUCTION

Although the need for continuous monitoring of Glaucoma patients is recognized by researchers and clinicians in the field, no method is so far available [4], [5]. Glaucoma is a widespread disease with intraocular pressure (IOP) as the main risk factor. According to the World Health Organization (WHO) estimates, there are 67 million people with Glaucoma worldwide and in the industrialized world, patients receiving treatment are some 5 million. Their treatment could be optimized (and costs reduced) with improved diagnostic tools. Detailed knowledge of IOP behavior in Glaucoma patients is of paramount importance for the understanding and the prognosis of the disease evolution as increased IOP is known to cause optic nerve degeneration.