Imaging-controlled laser surgical system

1. An imaging-based laser system, comprising:

a laser-beam system, including

a laser engine, configured to generate a beam of laser pulses,

a beam attenuator, configured to modify a laser-power parameter of the laser pulses, wherein the laser-power parameter is one of a pulse energy, a pulse power, a pulse length and a pulse repetition rate, and

a beam scanner, configured to scan the beam to points of a cylindrical scan-pattern in an eye; and

an imaging-based laser-controller, configured to:

image a layer in the eye that is tilted relative to an optical axis of the laser system,

determine z-depths of a sequence of points in the cylindrical scan-pattern that correspond to the imaged layer in the eye,

generate a tracking band within the cylindrical scan pattern defining a cut to be made in the eye, wherein a lower boundary of the tracking band has a non-uniform z-depth that varies according to the determined z-depths of the sequence of points corresponding to the imaged layer,

cause the beam scanner to scan the beam of laser pulses to the points of the cylindrical scan-pattern, and

cause the beam attenuator to control the laser-power parameter of the laser pulses such that a laser power parameter of laser pulses in the tracking band is above a photo-disruption threshold, and a laser power parameter of laser pulses outside the tracking band is below the photo-disruption threshold.

2. The laser system of claim 1 , the beam attenuator comprising at least one of:

a Pockels cell, a polarizer-assembly, a mechanical shutter, an electro-mechanical shutter, and an energy wheel.

3. The laser system of claim 1 , wherein:

the beam attenuator is disposed between the laser engine and the beam scanner in a path of the beam.

4. The laser system of claim 1 , wherein:

the beam attenuator is disposed after the beam scanner in a path of the beam.

5. The laser system of claim 1 , wherein:

the beam attenuator is part of the laser engine.

6. The laser system of claim 1 , wherein:

the beam attenuator and the beam scanner are at least partially integrated.

7. The laser system of claim 1 , the laser-controller comprising:

an imaging system, configured to image the imaged layer in the eye; and

a pattern generator, configured to:

generate coordinates of each point within the cylindrical scan-pattern,

associate a particular laser-power parameter with each point in the cylindrical scan pattern based on the tracking band, and

signal the generated coordinates of each point to the beam scanner, and

signal the particular laser-power parameter of each point to the beam attenuator.

8. The laser system of claim 7 , the imaging system comprising:

at least one of an ophthalmic coherence tomography system, a Scheimpflug imaging system, a scanning imaging system, a single shot imaging system, an ultrasound imaging system, and a video imaging system.

9. The laser system of claim 7 , wherein:

the imaging system is configured to image the imaged layer in an image region, wherein the image region

is based on one of a loop, an arc, a line, and a two-dimensional pattern transverse to an axis of the imaging system, and

extends to an image depth along the axis of the imaging system.

10. The laser system of claim 7 , wherein:

the imaging system is configured to support a determination of a z-depth coordinate of the imaged layer corresponding to a scanning coordinate along an image-scan.

11. The laser system of claim 10 , wherein:

the laser system comprises an operator interface; and

the imaging system is configured to support the determination of the z depth coordinate of the imaged layer using an input from an operator through the operator interface.

12. The laser system of claim 11 , wherein:

the operator interface is configured to assist the operator to fit a model curve to the image of the imaged layer.

13. The laser system of claim 11 , wherein:

the operator interface is capable of receiving the operator-input from at least one of a keyboard, a touch-screen, a computer-communication channel, an external memory, a flash-drive, an internet connection, a speech-recognition apparatus and a wireless connection.

14. The laser system of claim 10 , wherein:

the imaging system is configured to determine the z-depth coordinate of the imaged layer by performing a feature-recognition analysis of the image of the imaged layer.

15. The laser system of claim 14 , wherein:

the imaging system is configured to utilize at least one of a result of a pre-surgery measurement, statistical data, video image data, ophthalmic coherence tomography image data,

and a model-based computation during the determination of the z-depth.

16. The laser system of claim 10 , wherein:

the imaging system is configured to forward the z-depth and scanning coordinates of the imaged layer to the pattern generator; and

the pattern generator is configured

to determine the distance of the points of the scan-pattern from the imaged layer based on the forwarded coordinates of the imaged layer and the generated coordinates of the points,

to associate a first laser-power parameter above a photodisruption threshold with a first set of points closer to the imaged layer than a predetermined distance, and

to associate a second laser-power parameter below a photodisruption threshold with a second set of points farther from the imaged layer than the predetermined distance.

17. The laser system of claim 10 , wherein:

the imaging system is configured to forward the z-depth and scanning coordinates of the imaged layer to the pattern generator; and

the pattern generator is configured

to determine the distance of the points of the scan-pattern from the imaged layer based on the forwarded coordinates of the imaged layer and the generated coordinates of the points, and

to associate with the coordinates of the points a laser-power parameter that is a decreasing function of the distance of the points from the imaged layer.

18. The laser system of claim 7 , wherein:

the imaging system is configured to forward the image of the imaged layer to the pattern generator; and

the pattern generator is configured

to receive the image from the imaging system, and

to determine a z-depth coordinate of the imaged layer corresponding to a scanning coordinate along an image scan.

19. The laser system of claim 18 , wherein:

the pattern generator is configured to determine the z-depth of the imaged layer in part by performing a feature-recognition analysis of the received image of the imaged layer.

20. The laser system of claim 18 , wherein:

the pattern generator is configured to receive an operator input through an operator interface during the process of determining the z-depth of the imaged layer.

21. The laser system of claim 20 , wherein:

the operator interface is capable of receiving the operator-input from at least one of a keyboard, a touch-screen, a computer-communication channel, an external memory, a flash-drive, an internet connection, a speech-recognition apparatus and a wireless connection.

22. The laser system of claim 18 , wherein:

the pattern generator is configured to:

generate the tracking band as a manifold of points within a predefined distance from the coordinates of the imaged layer;

associate a laser-power parameter above a photodisruption threshold with points of the scan-pattern inside the tracking band, and

to associate a laser-power parameter below a photodisruption threshold with points of the scan-pattern outside the tracking band.

23. The laser system of claim 7 , the laser controller comprising:

an image analyzer, configured to determine a z-depth coordinate of the imaged layer corresponding to a scanning coordinate along an image-scan.

24. The laser system of claim 23 , wherein:

the image analyzer is configured to determine the z-depth coordinate of the imaged layer by performing a feature-recognition analysis of the image of the imaged layer.

25. The laser system of claim 23 , wherein:

the image analyzer is configured to determine the z-depth coordinate of the imaged layer by receiving an operator input through an operator-interface.

26. The laser system of claim 23 , wherein:

the image analyzer is at least partially integrated with one of the imaging system and the pattern generator.

27. The laser system of claim 1 , wherein:

the imaged layer is a lens capsule between a lens of an eye and an aqueous anterior chamber of the eye;

the scan-pattern corresponds to a cylindrical capsulotomy cut intersecting the lens capsule; and

the imaging-based laser controller is configured to:

associate a photodisruptive laser-power parameter with points inside a tracking band related to the intersection of the cylindrical capsulotomy cut and the lens capsule, and

associate a non-photodisruptive laser-power parameter with points outside the tracking band.

28. The laser system of claim 27 , wherein:

the laser system is configured to perform a capsulotomy before a lens fragmentation during a cataract procedure.

29. The laser system of claim 27 , wherein:

the imaging-based laser controller is configured to to analyze an image of the capsule boundary layer with more than two local extrema by at least one of a pattern generator and an image analyzer.