OPTIMIZING VISION CORRECTION PROCEDURES

• US 20100110379A1
• Filed: 10/23/2009
• Published: 05/06/2010
• Est. Priority Date: 01/20/2006
• Status: Active Grant

• Current Assignee: Clarity Medical Systems, Inc.
• Original Assignee: Clarity Medical Systems, Inc.
• Inventors: BAKER, PHILLIP, LINDER, BARRY, ZHOU, YAN, SHEA, WILLIAM
• Granted Patent: US 8,100,530 B2
• Time in Patent Office: Days
• US Class Current: 351/211
• CPC Class Codes: A61B 3/0025 characterised by electronic signal processing, e.g. eye models
• CPC Class Codes: A61B 3/0041 characterised by display arrangements
• CPC Class Codes: A61B 3/0091 Fixation targets for viewing direction
• CPC Class Codes: A61B 3/036 for testing astigmatism
• CPC Class Codes: A61B 3/10 Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions
• CPC Class Codes: A61B 3/1015 for wavefront analysis
• CPC Class Codes: A61B 3/103 for determining refraction, e.g. refractometers, skiascopes
• CPC Class Codes: A61B 3/1035 for measuring astigmatism testing astigmatism A61B3/036
• CPC Class Codes: A61B 3/13 Ophthalmic microscopes
• CPC Class Codes: A61B 3/14 Arrangements specially adapted for eye photography apparatus or arrangements for taking photographs per se G03B
• CPC Class Codes: A61B 5/7415 Sound rendering of measured values, e.g. by pitch or volume variation A61B5/741 takes precedence
• CPC Class Codes: A61B 90/20 Surgical microscopes characterised by non-optical aspects
• CPC Class Codes: G01J 2003/064 Use of other elements for scan, e.g. mirror, fixed grating
• CPC Class Codes: G01J 9/00 Measuring optical phase difference devices or arrangements for controlling the phase of light beams G02F1/01; Determining degree of coherence; Measuring optical wavelength spectrometry G01J3/00

Abstract

In one embodiment, an apparatus for optimizing vision correction procedures comprising: a narrow beam of light directed to a patient'"'"'s retina; a dynamic defocus and compensation offsetting device configured to offset the defocus of a wavefront from an eye, a wavefront sensor configured to measure the local tilt of a number of subwavefronts sampled around an annular ring (the diameter of which can be dynamically changed) over the wavefront with the defocus offset; and a display device configured to display a two dimensional (2D) data points pattern in real time with each data point location representing a corresponding local tilt of the sampled subwavefronts. A proper defocus offset, not passive compensation, can reveal the predominant feature(s) of other wavefront aberration component(s), thus enabling a refractive surgeon to fine tune the vision correction procedure and minimize the remaining wavefront aberration(s) in real time. Meanwhile, by sampling the wavefront around annular rings and displaying the local tilt of the sampled subwavefronts on a monitor in the form of a 2D data points pattern, a refractive ophthalmic surgeon can easily correlate the measurement result to the two major refractive errors, namely spherical and cylinder refractive errors, including the axis of astigmatism.

Claims

1. An apparatus comprising:

a dynamic wavefront sensor configured to receive a portion of a wavefront and output position values indicating the position of focused subwavefronts, with the portion of the wavefront comprising a plurality of subwavefronts;

a controllable wavefront offsetting element positioned to intercept the portion of the wavefront before it is incident on the wavefront sensor;

and

a controller, coupled to the controllable wavefront offsetting element, configured to control the controllable wavefront offsetting element to offset selected wavefront aberration components of the wavefront in order to allow remaining aberration components of the portion of wavefront to be more efficiently detected

2. The apparatus of claim 1 where the controllable wavefront offsetting element comprises:

a lens combination that introduces spherical refractive offset into the portion of the wavefront.

3. The apparatus of claim 2 where the controllable wavefront offsetting element comprises:

a positive negative lens combination with relative axial movement;

with the controller further configured to control the axial movement.

4. The apparatus of claim 1 where the controllable wavefront offsetting element comprises:

a dynamic wavefront manipulation device for offsetting selected aberration components of the portion of the wavefront; and

with the controller further configured to control the dynamic wavefront manipulation device.

5. The apparatus of claim 1 further comprising:

an internal fixation/visual acuity module positioned to project a pattern onto the retina of a patient'"'"'s eye.

6. The apparatus of claim 1 where the position values indicate the x and y values of the focused subwavefront from a reference point being the position value of the subwavefront of plane wave and further comprising:

a display configured to display data points representing the position values relative to the reference point.

7. The apparatus of claim 6 where the controller has a user input interface and further comprising:

a user input device, coupled to the user input, for providing inputs to control the wavefront offsetting element to controllably cancel part of the aberrations of the input wavefront.

8. The apparatus of claim 1 with the dynamic wavefront sensor comprising:

a sub-wavefront focusing lens configured to focus a sub-wavefront to an image spot located on a focal plane;

a sequential wavefront scanning device configured to sequentially project sub-wavefronts, located on an annular ring of the portion of the wavefront, onto the sub-wavefront focusing lens;

a variable aperture configured to control the size of a focused sub-wavefront;

a position sensing device, located substantially at the focal plane of the sub-wavefront focusing lens, configured to indicate the location of the image spot on the focal plane;

and

with the controller, further coupled to the position sensing device, variable aperture, further configured to coordinate the operation of the position scanning device and the variable aperture.

9. The apparatus of claim 8 where:

the position sensing device measures the tilt of a sub-wavefront as a displacement of a centroid of a focused sub-wavefront incident on the position sensing device.

10. The apparatus of claim 9 further comprising:

a display configured to display data points indicating the position values relative to the reference point.

11. An apparatus comprising:

a sub-wavefront focusing lens configured to focus a sub-wavefront, being an incident portion of a wavefront generated by a light source, to an image spot located on a focal plane;

a sequential wavefront scanning device configured to sequentially project different portions of an incident wavefront on the sub-wavefront focusing lens;

a variable aperture configured to control the size of the sub-wavefront;

a position sensing device, located substantially at the focal plane of the sub-wavefront focusing lens, configured to indicate the location of the image spot on the focal plane;

a controllable wavefront offsetting element positioned to intercept the portion of the wavefront before it is incident on the wavefront sensor;

and

a controller, coupled to the controllable wavefront offsetting element, configured to control the controllable wavefront offsetting element to offset selected wavefront aberration components of the wavefront in order to allow remaining aberration components of the portion of wavefront to be more efficiently detected.

12. The apparatus of claim 11 where the controllable wavefront offsetting element comprises:

a lens combination that introduces spherical refractive offset into the portion of the wavefront.

13. The apparatus of claim 12 where the controllable wavefront offsetting element comprises:

a positive negative lens combination with relative axial movement;

with the controller further configured to control the axial movement.

14. The apparatus of claim 11 where the controllable wavefront offsetting element comprises:

a dynamic wavefront manipulation device for offsetting selected aberration components of the portion of the wavefront; and

with the controller further configured to control the dynamic wavefront manipulation device.

15. The apparatus of claim 11 where the controller is further configured to control the variable aperture.

16. A method comprising:

sampling subwavefronts from a wavefront returned from the retina of the eye with a wavefront sensor, where the wavefront is a portion of a narrow beam of light directed to the retina of the eye and returned to the wavefront sensor and with the subwavefronts disposed on an annular ring portion of the wavefront;

measuring, using the wavefront sensor, position values for each subwavefront, where each position value indicates the offset of a focused subwavefront centroid from a reference point being the position of the centroid of a reference plane wave wavefront and where the wavefront sensor outputs position values in real-time;

changing, using a processor, the spherical refractive offset, introduced into the wavefront by a controllable wavefront offsetting element, in a first direction to a first selected offset position, with the controllable wavefront offsetting element positioned to intercept the wavefront before the wavefront is incident on the wavefront sensor and where the controllable wavefront offsetting element introduces a controllable spherical refractive offset into the wavefront;

computing, using the processor, Cartesian coordinates of measured position values at a current offset position;

displaying a shape comprising a trace of the current position values as data points on a display;

computing, using the processor, parameters relating to the ellipticity of a displayed shape;

computing, using the processor, values of wavefront tilts at the current offset position;

if the value of the wavefront tilt is within the dynamic range of the wavefront sensor, changing, using the processor, the spherical refractive offset, introduced into the wavefront by a controllable wavefront offsetting element, in the first direction to a second selected offset position;

computing, using the processor, Cartesian coordinates of measure position values at a first current offset position;

displaying a shape comprising a trace of the current position values as data points on a display;

computing, using the processor, parameters relating to the ellipticity of a displayed shape;

computing, using the processor, values of wavefront tilts at the current offset position;

if the value of the wavefront tilt is outside the dynamic range of the wavefront sensor terminating scanning in a current direction; and

from the ellipses obtained by scanning the offset, determining the best offset value from the ellipses obtained by scanning that can highlight remaining aberrations; and

returning information to a refractive surgeon on how to best continue a vision correction procedure.

17. A method comprising:

sampling subwavefronts from a wavefront returned from the retina of the eye with a wavefront sensor, where the wavefront is a portion of a narrow beam of light directed to the retina of the eye and returned to the wavefront sensor and with the subwavefronts disposed on an annular ring portion of the wavefront;

measuring position vectors for each subwavefront, using the dynamic wavefront sensor, where each position vector indicates the offset of a focused subwavefront centroid from a reference point being the position of the centroid of a reference plane wave wavefront and where the wavefront sensor outputs position values in real-time;

computing a midpoint vector, using a processor, of raw position vectors output by the wavefront sensor;

translating, using the processor, all the raw position vectors by the midpoint vector;

computing, using the processor, the average length of translated position vectors to determine the average radius of an enclosing circle;

comparing, using the processor, each translated position vector length to the average radius to select all position vectors having a vector length larger than the selected radius;

curve fitting, using the processor, all selected position vectors to determine an orientation angle of a straight line that best fits the selected position vectors, where the orientation angle is one of the axes of astigmatism;

rotating, using the processor, all translated position vectors by the orientation angle to place the major and minor axes orthogonal to an x,y coordinate system;

determining, using the processor, the magnitudes of semi-major and semi minor axes by curve fitting the rotated point vectors to the formula for an ellipse;

computing, using the processor, the spherical and cylindrical refractive errors in diopters using the magnitudes of the semi-major and semi-minor axes;

computing, using the processor, the error from a fitted ellipse to indicate the presence of higher order aberrations which can be further analyzed to determine corrective measures; and

determining, using the processor, the minor axis length or the major over minor axis length ratio of the fitted ellipse to determine if the fitted ellipse is close to circle or a data point or a straight line; and

outputting, using the processor, a signal to change the spherical refractive offset, introduced into the wavefront by a controllable wavefront offsetting element, to change the spherical refractive offset so the fitted ellipse is closer to a circle or a data point or a straight line.