title: Compact portable ocular microtremor sensor: design, development and calibration.
abstract: Ocular microtremor (OMT) is a physiological high-frequency (up to 150 Hz) low-amplitude (25-2500 nm peak-to-peak) involuntary motion of the human eye. Recent studies suggest a number of clinical applications for OMT that include monitoring the depth of anesthesia of a patient in surgery, prediction of outcome in coma, and diagnosis of brain stem death. Clinical OMT investigations to date have used mechanical piezoelectric probes or piezoelectric strain gauges that have many drawbacks which arise from the fact that the probe is in contact with the eye. We describe the design of a compact noncontact sensing device to measure OMT that addresses some of the above drawbacks. We evaluate the system performance using a calibrated piezoelectric vibrator that simulates OMT signals under conditions that can occur in practice, i.e., wet eye conditions. We also test the device at low light levels well within the eye safety range.
authors.affiliation: University College Dublin, School of Electronic, Electrical and Mechanical Engineering, Dublin 4, Republic of Ireland.
authors.forename: James P
authors.initials: JP
authors.lastname: Ryle
authors.forename: Mohammed
authors.initials: M
authors.lastname: Al-Kalbani
authors.forename: Niamh
authors.initials: N
authors.lastname: Collins
authors.forename: Unnikrishnan
authors.initials: U
authors.lastname: Gopinathan
authors.forename: Gerard
authors.initials: G
authors.lastname: Boyle
authors.forename: Davis
authors.initials: D
authors.lastname: Coakley
authors.forename: John T
authors.initials: JT
authors.lastname: Sheridan
mesh_terms: D003941:Diagnostic Techniques, Ophthalmological / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D053483:Eye Movement Measurements / Q000295:instrumentation*; D005133:Eye Movements / Q000502:physiology*; D006801:Humans; D007368:Interferometry / Q000295:instrumentation*; D007834:Lasers; D008904:Miniaturization; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014159:Transducers; D014732:Vibration