| 摘要 |
A tonometer for measuring the intraocular pressure of an eye featuring an acoustic signaling system for determining the beginning of a pressure measurement. The acoustic system includes a consumable cap having a pair of annular raised surface portions spaced by a recessed area. The raised surface portions provide an eye-engaging surface at the face of the tonometer. A pressure transmitting plunger concentrically suspended between the raised surface portions by a plurality of spider arms combines with the eye-engaging surface to provide a contour which complements a shape of an eye. The recessed area is open along the eye-engaging surface, yet defines a generally enclosed volume when full tonometer-to-eye contact is made. Spaced apart inlet and outlet apertures within the recessed area permit channeling of an acoustic signal to and from the recessed area. Prior to proper coupling of the tonometer to an eye, a substantial amount of the energy of the acoustic signal is lost to free air. However, upon achieving full tonometer-to-eye contact the energy is captured within the recessed ara and channeled to an acoustic receiver when the plunger contacts the eye, constricting the inlet-to-outlet acoustic wave path. Characteristic change of the received signal is marked by a hold signal triggered to initiate an intraocular pressure measurement. Proper coupling may be detected by either monitoring the phase or the change in amplitude at the acoustic wave receiver. Intraocular pressure is measured by means of the plunger which is operatively coupled to a force transducer.
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