OBJECTIVE PHOROPTER SYSTEM

• US 20150042957A1
• Filed: 04/04/2013
• Published: 02/12/2015
• Est. Priority Date: 04/05/2012
• Status: Active Grant

• Current Assignee: Visionix Ltd.
• Original Assignee: Visionix Ltd.
• Inventors: Abitbol, Marc, Yam, Ran, Herman, Haggai, Melnick, Ian
• Granted Patent: US 9,462,939 B2
• Time in Patent Office: Days
• US Class Current: 351/235
• CPC Class Codes: A61B 3/0285 Phoropters
• CPC Class Codes: A61B 3/1015 for wavefront analysis
• CPC Class Codes: F04C 2270/041 Controlled or regulated

Abstract

Systems for performing combined phoropter and refractive measurements to ascertain the aberrations present in the eye of a subject. The systems use a pair of phoropter wheel assemblies, one for each eye, each assembly comprising a number of lens wheels incorporating the series of lenses and wedges required to compensate for a range of refractive vision aberrations. The vision of each eye is corrected by a combination of a subjective phoropter measurement, iteratively performed with an objective wavefront analysis measurement to determine the residual aberrations existing after the initial phoropter correction. The system is able to automatically align the axes of each wavefront analyzer with is corresponding eye, by means of centering the pupil image in the wavefront analyzer camera, and to determine the pupil distance. By changing the focusing point on the wavefront analyzer of the light refleeted from the eye, the corneal profile can be measured.

Claims

1. A system for measuring the refractive properties of the eyes of a subject, said system comprising:

an optical system for directing illuminating beams into the eyes of the subject;

a phoropter comprising separate phoropter assemblies disposed in front of each of the eyes of the subject, such that the vision of each of the eyes of the subject can be subjectively corrected;

at least one of a lateral adjustment mechanism for the phoropter assemblies, or an angular adjustment mechanism for the angular alignment between the phoropter assemblies for each of the eyes of said subject, and

a wavefront analyzer for determining the aberrations of each of the eyes of the subject, said wavefront analyzers being disposed such that light emitted from each of said eyes enters their associated wavefront analyzers after traversing their associated phoropter assemblies,

wherein at least one of said phoropter adjustment mechanisms is adapted to enable said illuminating beams to be directed into the eyes of the subject along beam paths not coincident with the optical axes of the eyes of the subject.

2. A system according to claim 1 wherein said lateral adjustment mechanism for the phoropter assemblies is adapted to measure the subject'"'"'s pupil distance.

3. A system according to claim 2 wherein said lateral adjustment mechanism is controlled by determining the center of the subject'"'"'s pupils from an output of said wavefront analyzer.

4. A system according to claim 3 in which an output image of said wavefront analyzer is obtained on a detector array, and the intensity distribution of said output image is used to control said adjustment mechanisms of said phoropter.

5. A system according to any of the previous claims, further comprising illumination sources disposed laterally to said eyes, illuminating the surfaces of said eyes in a dark field mode, such that the wavefront analyzers generate images including arrays of spots from said dark field illumination scattered from the front surfaces of said eyes.

6. A system according to claim 5, wherein said images depict the position of the pupils of said eyes as regions with substantially less illumination than the rest of said images.

7. A system according to claim 6, further comprising an image processing system determining the position of said pupils, such that said wavefront analyzers system can be aligned relative to the centers of said pupils without the need for an additional viewing camera.

8. A system according to any of the previous claims, further comprising focusing assemblies directing light from said eyes into said wavefront analyzers, wherein said focusing assemblies and wavefront analyzers may be disposed on the axis of said eyes, light reflected from the corneal surfaces of said eyes being focused onto the central region of said wavefront analyzers, such that said corneal reflected light does not flood out light reflected from the retinae of said eyes impinging on more peripheral regions of said wavefront analyzer.

9. A system according to claim 8, wherein said focusing assemblies are such that said light reflected from the retinae of said eyes is directed into said wavefront analyzers in essentially collimated beams, such that said collimated beams cover an appreciable area of said wavefront analyzers peripheral to said central region of said wavefront analyzers.

10. A system according to any of the previous claims, wherein said paths not coincident with the optical axes of the eyes of the subject are sufficiently far from said optical axes that corneal reflections into said wavefront analyzers are essentially eliminated while the focused beams still impinge on the retinae of said eyes.

11. A system according to claim 10 wherein said illuminating beams are sufficiently small that said paths are sufficiently far from said optical axes.

12. A system according to claim 11, wherein the size of said illuminating beams may be increased to enable said increased-size beam to determine the positions of said optical axes of said eyes relative to the axes of said wavefront analyzers.

13. A system according to any of the previous claims, wherein said wavefront analyzers incorporate Shack-Hartmann arrays.

14. A system for measuring the refractive properties of an eye of a subject, said system comprising:

an optical system for directing an illuminating beam into an eye of the subject;

a phoropter disposed in front of said eye of the subject, such that the vision of the eye of the subject can be subjectively corrected; and

a wavefront analyzer for determining the aberrations of said eye of the subject, said wavefront analyzer being disposed such that light emitted from said eye enters said wavefront analyzer after traversing said phoropter,

wherein said optical system for directing said illuminating beam into an eye of the subject is disposed between said phoropter and said eye of the subject, such that said illuminating beam does not traverse said phoropter before impinging on said eye of said subject.

15. A system according to claim 14, wherein said optical system for directing said illuminating beam into said eye of the subject has a thickness in the direction of the optical axis of said system such that said phoropter can be positioned no further than a standard distance of spectacle lenses from the eye.

16. A system according to claim 14, wherein said optical system for directing said illuminating beam into said eye of the subject comprises a plate having beam splitting properties over only a central part of its aperture.

17. A method for measuring properties of the eye of a subject, comprising:

providing a wavefront analyzer for determining the aberrations of a wavefront reflected from said eye of the subject, light from said eye being directed into said wavefront analyzer by means of a focusing system; and

adjusting the axial position said focusing system such that the beam width of corneal reflected light entering said wavefront analyzer, is adjusted according to the properties of said eye which it is desired to measure.

18. A method according to claim 17, wherein said axial position of said focusing system is adjustable to provide a beam of light reflected from the cornea of said eye of width sufficiently large to enable the wavefront of said corneal reflected light to be analyzed by said wavefront analyzer, such that information regarding the corneal profile of said eye can be determined.

19. A method according to claim 17, wherein said axial position of said focusing system is adjustable such that said corneal reflected light enters said wavefront analyzer as a substantially collimated beam.

20. A method according to claim 17, wherein said axial position of said focusing system may be adjusted such that said beam of corneal reflected light is focused onto said wavefront analyzer in the central region of said wavefront analyzer.

21. A method according to claim 20, wherein when said axial position of said focusing system is adjusted such that said beam of corneal reflected light is focused onto said wavefront analyzer in the central region of said wavefront analyzer, light reflected from the retinal surface of said eye forms an essentially collimated beam at said wavefront analyzer, such that the aberrations of said eye can be measured from the deviations of said wavefront.

22. A method according to claim 21, wherein said essentially collimated beam enters said wavefront analyzer over a substantially larger area of said wavefront analyzer than said central region of said wavefront analyzer, such that said corneal reflected light does not flood out the retinally reflected light entering said wavefront analyzer over said substantially larger area.

23. A method according to claim 17, wherein said wavefront analyzer can be switched between eye aberration measurements and corneal profile measurements by adjustment of said axial position of said focusing system relative to the position of the eye being measured.

24. A method for determining aberrations in the eye of a subject by performing a sequential objective wavefront analysis of the residual aberration in the vision of the eye and a subjective phoropter measurement, using the objectively measured aberrations to adjust the settings of the vision correction elements in the subjective phoropter measurement, and repeating said measurements iteratively until the residual aberration is below a predetermined minimum value.

25. A method according to claim 24, comprising:

providing a measurement system incorporating;

a phoropter disposed in front of the eye of the subject, such that the vision of the eye of the subject can be subjectively corrected; and

a wavefront analyzer for determining objectively the aberrations of the eye of the subject after correction by said phoropter, said wavefront analyzer being disposed such that light emitted from said eye enters said wavefront analyzer after traversing said phoropter;

performing a first objective measurement of said eye using said wavefront analyzer;

adjusting the settings of said phoropter to correct the aberrations of said eye as measured by said first objective measurement;

performing a first subjective correction of the vision of said eye using said phoropter;

performing a second objective measurement of said eye using said wavefront analyzer, to determine the aberrations of said eye after said first subjective correction by said phoropter;

readjusting the settings of said phoropter to correct the aberrations of said eye as measured by said second objective measurement;

performing a second subjective correction of the vision of said eye using said phoropter with said readjusted settings;

determining whether the number of iterative steps has exceeded a predetermined number and if so outputting the last phoropter setting as the optimum prescription;

if the number of iterative steps has not exceeded said predetermined number, determining the residual aberration detected at the last objective wavefront analysis, and if less than a predetermined level, outputting the last phoropter setting as the optimum prescription; and

if the residual aberration detected at the last objective wavefront analysis is more than said predetermined level, continuing with said iterative objective and subjective measurements.