Noncontact type tonometer

• US 5,183,044 A
• Filed: 10/10/1991
• Issued: 02/02/1993
• Est. Priority Date: 06/30/1987
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaisha Topcon
• Original Assignee: Kabushiki Kaisha Topcon
• Inventors: Nishio, Kouji, Hanamura, Yoshihiko
• Primary Examiner(s): Kamm, William E.
• Assistant Examiner(s): PARKER, MARIANNE
• Application Number:
  US07/774,313
• Time in Patent Office: 481 Days
• Field of Search: 128/645, 128/648, 128/652
• US Class Current: 600/406
• CPC Class Codes: A61B 3/165 Non-contacting tonometers
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence

Abstract

A noncontact type tonometer projects a fluid toward an eye-to-be-tested and obtains a measured value of eye pressure from a relation between transfigurations of the eye due to the fluid projection and the pressure projecting the fluid. A detecting circuit senses a pulse wave of the person-to-be-tested and a calculating circuit determines at least one of the maximum eye pressure value, minimum eye pressure value and average eye pressure value of the eye dependent on the maximum fluctuation width of the detected pulse wave, a fluctuating quantity of the detected pulse wave, and the measured eye pressure value. The calculation circuit determines the pulse wave fluctuating quantity at the time point when the eye pressure is measured. The pulse wave of the person may be measured at a position remote from the eye. The tonometer may also include a display for displaying the pulse wave and a display controller for displaying the time point when the eye pressure is measured. The displayed eye pressure overlaps the displayed pulse wave to illustrate the relation between the measured eye pressure value and the pulse wave fluctuation.

Claims

1. A noncontact type tonometer comprising:

fluid projecting means for projecting a fluid toward an eye-to-be-tested;

eye pressure measuring means for obtaining a measured value of pressure of the eye-to-be-tested from a relation between a pressure of the fluid and a transfiguring quantity of the eye-to-be-tested due to the projection of the fluid;

pulse wave detecting means for detecting a pulse wave from of a person-to-be-tested at a position remote from the eye-to-be-tested due to the projection of the fluid; and

calculating means, communicating with the pulse wave detecting means and the eye pressure measuring means, for determining at least one of the maximum eye pressure value, minimum eye pressure value and average eye pressure value of the eye-to-be-tested through calculation with reference to;

a maximum fluctuation width of the pulse wave form detected by the pulse wave detecting means;

a pulse wave fluctuating quantity at the time point when the eye pressure was measured by the eye pressure measuring means;

a difference between a phase of the pulse wave form at the eye-to-be-tested and at the position remote from the eye-to-be-tested; and

the measured value of the eye pressure.

2. Method for operating a noncontact type tonometer comprising the steps:

projecting a fluid toward an eye-to-be-tested;

obtaining a measured value of pressure of the eye-to-be-tested from a relation between a pressure of the fluid and a transfiguring quantity of the eye-to-be-tested due to the projection of the fluid;

detecting a pulse wave from of a person-to-be-tested due to the projection of the fluid;

determining at least one of the maximum eye pressure value, minimum eye pressure value and average eye pressure value of the eye-to-be-tested through calculation with reference to;

a maximum fluctuation width of the detected pulse wave form;

a pulse wave fluctuating quantity at the time point when the eye pressure is measured; and

the measured value of the eye pressure.

3. The method of claim 2, further comprising the step, displaying the detected pulse wave form.

4. The method of claim 2, in which:

the pulse wave of the eye-to-be-tested is detected at a position remote from the eye-to-be-tested; and

the calculation for determining at least one of said pressure values is also with reference to,

a difference between a phase of the pulse wave form at the eye-to-be-tested and at the remote position on the person-to-be-tested.

5. The method of claim 3 in which, the detected pulse wave form is displayed through an image processing circuit.

6. The method of claim 3, further comprising the step, displaying the time point when the eye pressure was measure so as to overlap with the displayed pulse wave form.