title: Prototype of a nanostructured sensing contact lens for noninvasive intraocular pressure monitoring.
abstract: OBJECTIVE
  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).
  
  
  METHODS
  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.
  
  
  RESULTS
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: IOBA-Eye Institute, University of Valladolid, Valladolid, Spain 47011. isanchezp@ioba.med.uva.es
authors.forename: Irene
authors.initials: I
authors.lastname: Sánchez
authors.forename: Vladimir
authors.initials: V
authors.lastname: Laukhin
authors.forename: Ana
authors.initials: A
authors.lastname: Moya
authors.forename: Raul
authors.initials: R
authors.lastname: Martin
authors.forename: Fernando
authors.initials: F
authors.lastname: Ussa
authors.forename: Elena
authors.initials: E
authors.lastname: Laukhina
authors.forename: Anton
authors.initials: A
authors.lastname: Guimera
authors.forename: Rosa
authors.initials: R
authors.lastname: Villa
authors.forename: Concepcio
authors.initials: C
authors.lastname: Rovira
authors.forename: Jordi
authors.initials: J
authors.lastname: Aguiló
authors.forename: Jaume
authors.initials: J
authors.lastname: Veciana
authors.forename: Jose C
authors.initials: JC
authors.lastname: Pastor
mesh_terms: D000818:Animals; D003261:Contact Lenses; D004582:Electronics, Medical / Q000295:instrumentation; D005901:Glaucoma / Q000175:diagnosis*; D006801:Humans; D007429:Intraocular Pressure; D008991:Monitoring, Physiologic / Q000295:instrumentation*; D049329:Nanostructures; D011474:Prosthesis Design; D013552:Swine; D014159:Transducers