Non-contact tonometer

• US 5,076,274 A
• Filed: 09/04/1990
• Issued: 12/31/1991
• Est. Priority Date: 02/18/1987
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Matsumoto, Kazuhiro
• Primary Examiner(s): Cohen, Lee S.
• Assistant Examiner(s): LACYK, JOHN P
• Application Number:
  US07/577,076
• Time in Patent Office: 483 Days
• Field of Search: 128/645, 128/648, 128/652
• US Class Current: 600/401
• CPC Class Codes: A61B 3/165 Non-contacting tonometers

Abstract

An eye pressure meter provided with a pressing system for deforming the cornea of an eye to be examined, a detecting system for detecting the speed of deformation of the cornea, and a calculating system for calculating eye pressure value information on the basis of the information of the speed of deformation.

Claims

1. A non-contact tonometer comprising:

a pressurizing system, a deformation detection system, and a calculation system, wherein;

said pressurizing system includes;

fluid pressurizing chamber means for providing pressurized fluid; and

nozzle means for applying the pressurized fluid to deform a cornea of an eye to be examined, said nozzle means being coupled to said fluid pressurizing chamber means and adapted to be positioned opposite to the eye along a pressurization axis;

said deformation detection system includes;

light projection means for projecting a pulsed light beam to the cornea,

light receiving means for receiving a light beam reflected by the cornea during the deformation of the cornea; and

deformation speed detecting means for detecting the moving speed of the corneal surface being deformed in the direction of the pressurization axis on the basis of a frequency deviation between pulsed light beam projected to the cornea and the pulsed light beam reflected by the cornea;

said calculation system includes;

calculation means for calculating the eye pressure in accordance with the time integration of an output from said deformation speed detecting means.

2. A non-contact tonometer according to claim 1, wherein said light projection means and said light receiving means are coaxially arranged with said nozzle means.

3. A non-contact tonometer according to claim 1, wherein said calculation means includes means which calculates the eye pressure on the basis of a time period until the time integrated value of the output of said deformation speed detecting means reaches a predetermined value.

4. A non-contact tonometer according to claim 1, wherein said calculation means includes means which calculates the eye pressure on the basis of the time integrated value of the output of said deformation speed detecting means at a time after a predetermined time interval has expired.

5. A non-contact tonometer according to claim 1, wherein said fluid pressurizing chamber means includes means for providing pressurized air to said nozzle means.

6. A non-contact tonometer according to claim 1, wherein said fluid pressurizing chamber means includes means for varying the pressure of the fluid output from said nozzle means over time.

7. A non-contact tonometer according to claim 1, wherein said fluid pressurizing chamber means includes means for providing the fluid output from said nozzle means in a pulse state and at a constant pressure.

8. A non-contact tonometer according to claim 1, wherein said light projecting means includes means for projecting infrared light.

9. A non-contact tonometer according to claim 1, wherein a light source in the light projection means and a light receiving element in the light receiving means are optically conjugately arranged with the corneal surface the eye and the corneal surface is appropriately aligned with said light source and said light receiving element before measurement of the eye pressure.

10. A non-contact tonometer according to claim 9, further comprising an indicating means for indicating that the alignment of the eye is appropriate when the output of said light receiving element reaches a predetermined value.

11. A non-contact tonometer according to claim 1, further comprising a fixation means for fixing a gazing point of the eye along the pressurization axis.

12. A non-contact tonometer according to claim 11, wherein said fixation means includes means for moving at least a part of said fixation means in the direction of an optical axis of the eye corresponding to the refractive power of the eye.

13. A non-contact tonometer according to claim 10, further comprising a fixation light source to be watched by the eye and a control means for changing a light emitting state of said fixation light source when the output of said light receiving element reaches a predetermined value.

14. An eye pressure meter according to claim 13, wherein said control means changes the output of said fixation light source between a flickering state and a turned-on state.

15. An eye pressure meter, comprising:

fluid pressurizing chamber means for providing pressurized fluid;

nozzle means for supplying the pressurized fluid to deform a cornea of an eye to be examined, said nozzle means being operably associated with said fluid pressurizing chamber means and adapted to be positioned opposite the eye along a pressurization axis;

projection means for projecting a pulse signal to the cornea;

receiving means for receiving the signal reflected by the cornea during the deformation of the cornea;

deformation speed detecting means for detecting the moving speed of the corneal surface being deformed in the direction of the pressurization axis on the basis of a frequency deviation between the pulse signal projected to the cornea and the signal reflected by the cornea; and

calculation means for calculating the eye pressure in accordance with the time integration of an output from said deformation speed detecting means.

16. A non-contact tonometer comprising:

a pressurizing system, a deformation detection system, and a calculation system, wherein;

said pressurizing system includes;

fluid pressurizing chamber means for providing pressurized fluid; and

nozzle means for applying the pressurized fluid to deform a cornea of an eye to be examined, said nozzle means being coupled to said fluid pressurizing chamber means and adapted to be positioned opposite the eye along a pressurization axis;

said deformation detection system includes;

light projection means for projecting a pulsed light beam to the cornea;

light receiving means for receiving a light beam reflected by the cornea during the deformation of the cornea; and

deformation speed detecting means for detecting the moving speed of the cornea being deformed in the direction of the pressurization axis on the basis of a frequency deviation between the pulsed light beam projected to the cornea and the pulsed light beam reflected by the cornea;

said calculation system includes;

calculation means for calculating the eye pressure in accordance with an extremum value of an output from said deformation speed detecting means.

17. A non-contact tonometer comprising:

a pressurizing system, a deformation detection system, and a calculation system, wherein;

said pressurizing system includes;

fluid pressurizing chamber means for providing pressurized fluid; and

nozzle means for applying the pressurized fluid to deform a cornea of an eye to be examined, said nozzle means being coupled to said fluid pressurizing means and adapted to be positioned opposite the eye along a pressurization axis;

said deformation detection system includes;

light projection means for projecting a light beam with a predetermined wavelength to the cornea;

light receiving means for receiving a light beam reflected by the cornea during the deformation of the cornea; and

deformation speed detecting means for detecting the moving speed of the cornea being deformed in the direction of the pressurization axis on the basis of wavelength deviation between the light beam projected to the cornea and the light beam reflected by the cornea;

said calculation system includes;

calculation means for calculating the eye pressure on the basis of the time integration of an output from said deformation speed detecting means.

18. A non-contact tonometer comprising:

a pressurizing system, a deformation detection system, and a calculation system, wherein;

said pressurizing system includes;

fluid pressurizing chamber means for providing pressurized fluid; and

nozzle means for applying the pressurized fluid to deform a cornea of an eye to be examined, said nozzle means being coupled to said fluid pressurizing chamber means and adapted to be positioned opposite the eye along a pressurization axis;

said deformation detection system includes;

light projection means for projecting a light beam with a predetermined wavelength to the cornea;

light receiving means for receiving a light beam reflected by the cornea during the deformation of the cornea; and

deformation speed detecting means for detecting the moving speed of the cornea being deformed in the direction of the pressurization axis on the basis of a wavelength deviation between the light beam projected to the cornea and the light beam reflected by the cornea;

said calculation system includes;

calculation means for calculating the eye pressure in accordance with an extremum value of an output from said deformation speed detecting means.

19. A non-contact tonometer comprising:

a pressurizing system, a deformation detection system, and a calculation system, wherein;

said pressurizing system includes;

pressurizing energy means for deforming a cornea of an eye to be examined, said pressurizing energy means being adapted to be positioned opposite the eye along a pressurization axis;

said deformation detection system includes;

light projection means for projecting a pulsed light beam to the cornea;

light receiving means for receiving a light beam reflected by the cornea during the deformation of the cornea; and

deformation speed detecting means for detecting the moving speed of the cornea being deformed in the direction of the pressurization axis on the basis of a frequency deviation between the pulsed light beam projected to the cornea and the light beam reflected by the cornea;

said calculation system includes;

calculation means for calculating the eye pressure on the basis of the time integration of an output from said deformation speed detecting means.

20. A non-contact tonometer comprising:

a pressurizing system, a deformation detection system, and a calculation system, wherein;

said pressurizing system includes;

pressurizing energy means for deforming a cornea of an eye to be examined, said pressurizing energy means being adapted to be positioned opposite the eye along a pressurization axis;

said deformation detection system includes;

light projection means for projecting a pulsed light beam to the cornea;

light receiving means for receiving a light beam reflected by the cornea during the deformation of the cornea; and

deformation speed detecting means for detecting the moving speed of the cornea being deformed in the direction of the pressurization axis on the basis of a frequency deviation between pulsed light beam projected to the cornea and the light beam reflected by the cornea;

said calculation system includes;

calculation means for calculating the eye pressure in accordance with an extremum value of an output from said deformation speed detecting means.

21. A non-contact tonometer comprising:

a pressurizing system, a deformation detection system, and a calculation system, wherein;

said pressurizing system includes;

pressurizing energy means for deforming a cornea of an eye to be examined, said pressurizing energy means being adapted to be positioned opposite the eye along a pressurization axis;

said deformation detection system includes;

light projection means for projecting a light beam with a predetermined wavelength to the cornea;

light receiving means for receiving a light beam reflected by the cornea during the deformation of the cornea; and

deformation speed detecting means for detecting the moving speed of the cornea being deformed in the direction of the pressurization axis on the basis of a wavelength deviation between the pulsed light beam projected to the cornea and the light beam reflected by the cornea;

said calculation system includes;

calculation means for calculating the eye pressure on the basis of the time integration of an output from said deformation speed detecting means.

22. A non-contact tonometer comprising:

a pressurizing system, a deformation detection system, and a calculation system, wherein;

said pressurizing system includes;

pressurizing energy means for deforming a cornea of an eye to be examined, said pressurization energy means being adapted to be positioned opposite the eye along a pressurization axis;

said deformation detection system includes;

light projection means for projecting a light beam with a predetermined wavelength to the cornea;

light receiving means for receiving a light beam reflected by the cornea during the deformation of the cornea; and

deformation speed detecting means for detecting the moving speed of the cornea being deformed in the direction of the pressurization axis on the basis of a wavelength deviation between the pulsed light beam projected to the cornea and the light beam reflected by the cornea;

said calculation system includes;

calculation means for calculating the eye pressure in accordance with an extremum value of an output from said deformation speed detecting means.

23. A non-contact tonometer comprising:

a pressurizing system, a deformation detection system, and a calculation system, wherein;

said pressurizing system includes;

fluid pressurizing chamber means for providing pressurized fluid; and

nozzle means for applying the pressurized fluid to deform a cornea of an eye to be examined, said nozzle means being coupled to said fluid pressurizing chamber means and adapted to be positioned opposite the eye along a pressurization axis;

said deformation detection system includes;

light projection means for receiving a light beam reflected by the cornea during the deformation of the cornea;

light receiving means for receiving a light beam reflected by the cornea during the deformation of the cornea; and

deformation speed detecting means for detecting the moving speed of the cornea being deformed in the direction of the pressurization axis on the basis of a frequency deviation between the pulsed light beam projected to the cornea and the light beam reflected by the cornea;

said calculation system includes;

calculation means for calculating the eye pressure on the basis of an output from said deformation speed detecting means.

24. A non-contact tonometer comprising:

a pressurizing system, a deformation detection system, and a calculation system, wherein;

pressurizing energy means for deforming a cornea of an eye to be examined, said pressurizing energy means being adapted to be positioned opposite the eye along a pressurization axis;

said deformation detection system includes;

light projection means for projecting a pulsed light beam to the cornea;

light receiving means for receiving a light beam reflected by the cornea during the deformation of the cornea; and

deformation speed detecting means for detecting the moving speed of the cornea being deformed in the direction of the pressurization axis on the basis of a frequency deviation between the pulsed light beam projected to the cornea and the light beam reflected by the cornea;

said calculation system includes;

calculation means for calculating the eye pressure on the basis of an output from said deformation speed detecting means.

25. A non-contact tonometer, comprising:

fluid pressurizing chamber means for providing pressurized fluid;

nozzle means for supplying the pressurized fluid to deform a cornea of an eye to be examined, said nozzle means being operably associated with said fluid pressurizing chamber means and adapted to be positioned opposite the eye along a pressurization axis;

projection means for projecting a pulse signal to the cornea;

receiving means for receiving the signal reflected by the cornea during the deformation of the cornea;

detecting means for detecting a frequency deviation between the pulse signal projected to the cornea and the signal reflected by the cornea; and

calculation means for calculating the eye pressure on the basis of an output from said detecting means.

26. A non-contact tonometer according to claim 25, wherein said calculation means calculates the time integration of the output from said detecting means.

27. A non-contact tonometer according to claim 25, wherein said calculation means calculates an extended value of the output from said detecting means.

28. A non-contact tonometer, comprising:

a pressurizing system, a deformation detection system and a calculation system,

wherein said pressurizing system includes pressurizing energy means for deforming a cornea of an eye to be examined, said pressurizing energy means being adapted to be positioned opposite the eye along a pressurization axis;

wherein said deformation detection system includes;

projection means for projecting a pulse signal to the cornea;

receiving means for receiving the signal reflected by the cornea during the deformation of the cornea;

detecting means for detecting a frequency deviation between the pulse signal projected to the cornea and the signal reflected by the cornea; and

wherein said calculation system includes calculation means for calculating the eye pressure on the basis of an output from said detecting means.

29. A non-contact tonometer according to claim 28, wherein said calculation means calculates the time integration of the output from said detecting means.

30. A non-contact tonometer according to claim 28, wherein said calculation means calculates an extended value of the output from said detecting means.