Prototype of a nanostructured sensing contact lens for noninvasive intraocular pressure monitoring

• Published in: Investigative ophthalmology & visual science Vol. 52; no. 11; pp. 8310 - 8315
• Main Authors: Sánchez, Irene, Laukhin, Vladimir, Moya, Ana, Martin, Raul, Ussa, Fernando, Laukhina, Elena, Guimera, Anton, Villa, Rosa, Rovira, Concepcio, Aguiló, Jordi, Veciana, Jaume, Pastor, Jose C
• Format: Journal Article
• Language: English
• Published: United States 21.10.2011
• Subjects: Animals; Contact Lenses; Electronics, Medical - instrumentation; Glaucoma - diagnosis; Humans; Intraocular Pressure; Monitoring, Physiologic - instrumentation; Nanostructures; Prosthesis Design; Swine; Transducers
• ISSN: 1552-5783; 1552-5783
• DOI: 10.1167/iovs.10-7064

To present the application of a new sensor based on a flexible, highly piezoresistive, nanocomposite, all-organic bilayer (BL) adapted to a contact lens (CL) for non-invasive monitoring intraocular pressure (IOP). A prototype of a sensing CL, adapted to a pig eyeball, was tested on different enucleated pig eyes. A rigid, gas-permeable CL was designed as a doughnut shape with a 3-mm hole, where the BL film-based sensor was incorporated. The sensor was a polycarbonate film coated with a polycrystalline layer of the highly piezoresistive molecular conductor β-(ET)₂I₃, which can detect deformations caused by pressure changes of 1 mm Hg. The pig eyeballs were subjected to controlled-pressure variations (low-pressure transducer) to register the electrical resistance response of the CL sensor to pressure changes. Similarly, a CL sensor was designed according to the anatomic characteristics of the eye of a volunteer on the research team. A good correlation (r² = 0.99) was demonstrated between the sensing CL electrical response, and IOP (mm Hg) changes in pig eyes, with a sensitivity of 0.4 Ω/mm Hg. A human eye test also showed the high potential of this new sensor (IOP variations caused by eye massage, blinking, and eye movements were registered). A new nanostructured sensing CL for continuous monitoring of IOP was validated in an in vitro model (porcine eyeball) and in a human eye. This prototype has adequate sensitivity to continuously monitor IOP. This device will be useful for glaucoma diagnosis and treatment.