Patent ID: 7153267
Filing Date: 2006-12-26
Classification: A61B

Abstract:
1. A system ensuring replacement of a molded resin prism used in an applanation tonometer having a microprocessor and a holder for receiving the prism in an operating position, the system comprising: a. the prism being molded to form a bendable tab having an initial position extending transversely of a direction of insertion of the prism into the holder; b. a strain gauge arranged in the holder to engage the tab as the prism is being inserted into the holder and before the prism reaches the operating position; c. the strain gauge being arranged to bend the tab from its initial position to a bent position as the prism is moved fully into the holder to the operating position; d. the strain gauge being arranged to produce a tab bending signal delivered to the microprocessor representing the strain involved in bending the tab from its initial position to its bent position; e. the tab being configured so that a first bending of the tab from its initial position to its bent position requires more stress than any subsequent bending of the tab from its initial position to its bent position; f. the microprocessor being programmed to distinguish between a tab bending signal from the strain gauge representing the first bending of the tab and a tab bending signal from the strain gauge representing the subsequent bending of the tab; and g. the microprocessor being programmed to proceed with an eye examination only if a prism inserted into the holder causes the strain gauge to produce a tab bending signal representing the first bending of the tab.