Corneal surface temperature change as the mode of stimulation of the non-contact corneal aesthesiometer

Paul J. Murphy, Philip B. Morgan, Sudi Patel, John Marshall

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Purpose. The non-contact corneal aesthesiometer (NCCA) assesses corneal sensitivity by using a controlled pulse of air, directed at the corneal surface. The purpose of this paper was to investigate whether corneal surface temperature change was a component in the mode of stimulation. Methods. Thermocouple experiment: A simple model corneal surface was developed that was composed of a moistened circle of filter paper placed on a thermocouple and mounted on a glass slide. The temperature change produced by different stimulus pressures was measured for five different ambient temperatures. Thermal camera experiment: Using a thermal camera, the corneal surface temperature change was measured in nine young, healthy subjects after exposure to different stimulus air pulses. Pulse duration was set at 0.9 s but was varied in pressure from 0.5 to 3.5 millibars. Results. Thermocouple experiment: An immediate drop in temperature was detected by the thermocouple as soon as the air flow was incident on the filter paper. A greater temperature change was produced by increasing the pressure of the incident air flow. A relationship was found and a calibration curve plotted. Thermal camera experiment: For each subject, a drop in surface temperature was detected at each stimulus pressure. Furthermore, as the stimulus pressure increased, the induced reduction in temperature also increased. A relationship was found and a calibration curve plotted. Conclusion. The NCCA air-pulse stimulus was capable of producing a localized temperature change on the corneal surface. The principal mode of corneal nerve stimulation, by the NCCA air pulse, was the rate of temperature change of the corneal surface.
    Original languageEnglish
    Pages (from-to)333-342
    Number of pages9
    JournalCornea
    Volume18
    Issue number3
    DOIs
    Publication statusPublished - May 1999

    Keywords

    • Aesthesiometry
    • Corneal innervation
    • Corneal sensitivity
    • Mode of stimulation
    • Noninvasive

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