Note: Descriptions are shown in the official language in which they were submitted.
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APPARATUS AND METHOD FOR AUTO-TITRATING A LASER
TECHNICAL FIELD OF THE INVENTION
The present invention relates in general to laser systems. In particular, the
is present
invention relates to surgical laser systems. Even more particularly, the
present invention relates
to a system and method for automatic titration of a laser for use in
ophthalmic surgery.
BACKGROUND OF THE INVENTION
A number of ophthalmic surgical procedures performed on a patient's eye, such
as on the
retina, require irradiating a select portion of the eye with a light spot,
typically provided by a
laser, having a desired spot size. Examples of surgical procedures utilizing
lasers include photo-
dynamic therapy, LASIK, laser sclerlostomy, trabeculectomy, and general
endoscopic
microsurgical applications, including neural, arthroscopic, and spinal chord
surgery.
In one particular ophthalmic surgical procedure, typically referred to as
retinal
coagulation, a laser light spot is directed to a selected portion of a
patient's retina to deposit
energy, thereby causing coagulation of the local tissue. Such a
photocoagulation procedure can
be employed, for example, to seal leaky blood vessels, destroy abnormal blood
vessels, or seal
retinal tears. In preparation for such a laser procedure, and others, a
surgeon typically must place
several probing laser shots onto the retina to titrate the laser power for an
intended surgical
effect. The surgeon will typically start out with the laser set to a low power
setting and
incrementally increase the laser power until he or she observes a desired
tissue effect (e.g.,
discoloration) indicating that the laser power is at or beyond a level
required for the
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intended procedure. The surgeon will then finalize the laser power setting and
treat
the intended area.
The laser titrating procedure is performed manually by the surgeon, as
currently existing surgical lasers and surgical laser systems do not provide
the ability
to auto-titrate a surgical laser. If aspects of the laser titration procedure
were instead
automated, a surgeon could be freed from the additional setup steps required
to set the
surgical laser power for a surgical procedure, thus improving the efficiency
and flow
of the surgical procedure.
to
Therefore, a need exists for an apparatus and method for automatically
titrating a surgical laser that can reduce or eliminate the problems of prior
art surgical
lasers associated with manually titrating the surgical laser in preparation
for a surgical
procedure.
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BRIEF SUMMARY OF THE INVENTION
The embodiments of the auto-titrating laser apparatus and method of using a
surgical laser of the present invention substantially meet these needs and
others. One
embodiment of the method for auto-titrating a laser comprises: providing an
algorithm, wherein the algorithm is operable to configure the laser based on
one or
more user inputs; providing a first user input operable to cause the algorithm
to
execute and fire the laser in a defined pattern; providing a second user
input, in
response to an observed condition, operable to cause the laser to stop firing
and to
to cause the algorithm to determine one or more laser parameter values and
configure
the laser based on the one or more laser parameter values, wherein a final
laser power
value when the laser stops firing is an input to the algorithm and wherein the
algorithm determines the one or more laser parameters based on the final laser
power
value. The method can further comprise transitioning (placing) the laser to a
"ready"
(surgical) mode, either automatically by the auto-titration algorithm or via
another
user input. Once in a ready mode, a user, such as a surgeon, can perform a
surgical
procedure with the automatically configured laser. The surgeon can thus
transition
quickly and efficiently to performing the intended surgery with the laser
automatically
configured to his or her pre-defined settings.
One benefit of the embodiments of the present invention over the prior art is
thus the ability to automate portions of a titration procedure and settings
and thereby
improve the flow and efficiency of a surgical procedure. A surgeon can, for
example,
select a pre-defined titration ramp and initiate a pre-defined laser pulse
sequence by
activating a control switch, such as the footswitch typically used by
ophthalmic
surgeons to control the operation of an ophthalmic surgical laser. The surgeon
can
release the footswitch (or other control apparatus) upon observing a desired
effect on
the tissue being irradiated by the laser's beam. The time indication
(interval) of the
control device release can be used by the surgical laser system to configure
certain
laser operating parameters, such as laser power and pulse duration, for an
intended
surgical procedure based on the surgeon's pre-defined criteria. The operating
parameters set by the embodiments of the present invention may be higher,
lower or
correspond to the settings at the time of the control apparatus' release
depending on
the surgeon's predefined criteria.
Embodiments of the present invention can comprise an apparatus for auto-
titrating a surgical laser, comprising a processing module and a memory
operably
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coupled to the processing module, wherein the memory includes computer-
executable
software instructions operable to cause the processing module to perform at
least
some of the functions described herein. Embodiments of the apparatus for auto-
titrating a surgical laser can further comprise hardware operable to perform
at least
some of the functions described herein in response to signals from the
processing
module.
Embodiments of the present invention can be implemented within any
ophthalmic surgical laser system as known to those having skill in the art,
and in
particular, in the EYELITE Laser Surgical System manufactured by Alcon
Manufacturing, Ltd. of Irvine, California. The embodiments of this invention
can be
incorporated within any such surgical machine or system for use in ophthalmic
or
other surgery. Other uses for an apparatus and method for auto-titrating a
laser in
accordance with the teachings of this invention will be known to those having
ordinary skill in the art and are contemplated to be within the scope of this
invention.
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BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
A more complete understanding of the present invention and the advantages
thereof may be acquired by referring to the following description, taken in
conjunction with the accompanying drawings in which like reference numerals
indicate like features and wherein:
FIGURE 1 is a diagrammatic representation of an exemplary surgical laser
console in which an embodiment of the apparatus and method for auto-titrating
a laser
to of the present invention can be implemented;
FIGURE 2 is a close-up view of one embodiment of a user interface 12 in
accordance with the present invention;
FIGURE 3 is a graphical representation of the power vs. time profile of one
predefined titration procedure in accordance with an embodiment of this
invention;
FIGURE 4 is a flowchart illustrating the steps of one embodiment of the
method of this invention; and
FIGURE 5 is a functional block diagram of an embodiment of an apparatus for
auto-titrating a laser in accordance with the present invention.
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DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention are illustrated in the FIGUREs
like numerals being used to refer to like and corresponding parts of the
various
drawings.
The various embodiments of the present invention provide an auto-titrating
surgical laser and an apparatus and method of auto-titrating a laser, such as
a surgical
laser, that provide a user, such as a surgeon, the ability to automatically
configure
to certain laser parameters, in particular laser power, for use in a
surgical procedure
based on an observed effect and a pre-defined configuration (titration)
routine.
Embodiments of the present invention can comprise an auto-titrating surgical
laser, an
apparatus for auto-titrating a laser, and a method for configuring a laser.
The embodiments of the present invention provide a surgeon the ability to
automate a prior-art manual titration process in which a surgeon fires test
shots to
create test "burns" on the periphery of the retina, where burning causes
negligible
effects on a patient's vision, at various incrementally increasing laser power
settings
until a desired effect, such as whitening of the affected section of the
retina, is
observed. Once the whitening effect is observed, the surgeon knows that the
laser
power is higher than desired for retinal surgery, and he or she can set the
laser power
to a lower setting appropriate for an intended surgical result that will not
cause
unintended effects to the patient's retina (e.g., damage). For example, the
surgeon can
choose to lower power by a given factor (e.g., 20%). Typically, whitening of
the
retina at the test site indicates a laser power setting higher than desired
for the surgical
procedure.
Prior art surgical laser systems require a surgeon to manually titrate the
surgical laser, adjusting power in increments and then manually setting the
power to a
desired operational value once the tissue effect is observed. The embodiments
of the
present invention automate aspects of the titration procedure such that a
surgeon can
instead pre-define a titration algorithm that can automatically configure a
surgical
laser's parameters at the initiation of the surgeon. For example, one
embodiment of
this invention provides for an auto-titration function that allows the surgeon
to pre-
define one or more of pulse rate, pulse duration, laser power increments,
initial power
and maximum laser power. The surgeon can also pre-define the laser's surgical
(operational) power setting (i.e., the laser power used during the surgical
procedure),
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for example, as a function of the final titration power setting (the power
setting at the
point the desired tissue effect is observed and the surgeon stops the test
shots). For
example, the surgical power setting might be set 20% less than the final
titration
power setting. Other parameter settings, as will be known to those having
ordinary
skill in the art, can also be pre-defined for automatic configuration by an
embodiment
of the auto-titration algorithm of this invention.
Once the surgeon has pre-defined the auto-titration function, the embodiments
of the present invention operate to execute the function and automatically
configure
the surgical laser parameters for a surgery based on an input from the
surgeon. The
input could be the surgeon, while preparing for surgery, actuating a control
interface,
such as a button, a screen icon, a footswitch, or any other control mechanism
operable
to activate the laser or a laser function. In one embodiment, for example, the
surgeon
can actuate a footswitch to fire the laser. In accordance with the embodiments
of this
invention, the surgeon can activate the footswitch and fire the laser while in
the
titration mode (which can be initiated via a control interface on the surgical
laser/console), thus running the preset titration program (e.g., power
increments, pulse
durations, etc.) and placing one or more test shots on the patient's retina.
Once the
surgeon observes a desired tissue effect indicating a desired laser power
setting, he or
she can deactivate the laser (e.g., release the footswitch), which will cause
the auto-
titration program to automatically configure the selected laser parameters, in
particular laser power, to the selected surgical settings in accordance with
the pre-
defined criteria of the auto-titration program. The time indication (duration
the
surgeon fires laser test shots) is a primary input to determine surgical laser
settings
based on the laser operating parameters at the time the surgeon stops the
laser test
firing (titration). Once the auto-titration program sets the laser parameters
to their
surgical values, the surgical laser can be automatically transitioned into
treatment
mode and the surgeon can carry out the surgical procedure without
interruption.
FIGURE 1 is a diagrammatic representation of an exemplary surgical laser
console in which an embodiment of the apparatus and method for auto-titrating
a laser
of the present invention can be implemented. Laser 10 includes a user
interface 12,
various control knobs and/or buttons 14, probe port 16, illumination port 20,
on/off
key 22, and emergency shut-off 24. These control devices are exemplary only
and a
surgical laser/laser console may have any combination of these and perhaps
other
control interfaces and ports that may be useful in an ophthalmic laser system.
User
interface 12 can be a graphical user interface, including a touch-sensitive
screen, as
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will be known to those having ordinary skill in the art, for displaying and
allowing a
user to select functions and control/adjust parameters of the laser system 10.
The
various other controls and ports shown in FIGURE 1 can serve functions that
will be
apparent to those having ordinary skill in the art of ophthalmic laser
systems.
Laser 10 can further include a processing module 50 and an associated
memory 52, operably coupled to one another and to the control functions of the
surgical laser 10 console. The processing module 50 and the memory 52 are
operable
to store and execute operational instructions operable to cause laser 10 to
fire, change
settings, and other functions associated with a laser 10 as will be familiar
to those of
ordinary skill in the art. Processing module 50 and memory 52, in particular,
are
operable to store and execute computer (processing module) executable
software/operational instructions operable to cause laser to perform at least
some of
the functions of the method/algorithm of this invention described herein. Such
instructions can be hard-code and or operational instructions stored in memory
52 and
corresponding to at least some of the steps or functions described herein.
Processing module 50 may be a single processing device or a plurality of
processing devices. Such a processing device may be a microprocessor, micro-
controller, digital signal processor, microcomputer, central processing unit,
field
programmable gate array, programmable logic device, state machine, logic
circuitry,
analog circuitry, digital circuitry, and/or any device that manipulates
signals (analog
and/or digital) based on hard coding of the circuitry and/or operational
instructions.
Memory 52 may be a single memory device, a plurality of memory devices, and/or
embedded circuitry of the processing module. Memory 52 may be a read-only
memory, random access memory, volatile memory, non-volatile memory, static
memory, dynamic memory, flash memory, cache memory, and/or any device that
stores digital information. Note that when the processing module 50 implements
one
or more of its functions via a state machine, analog circuitry, digital
circuitry, and/or
logic circuitry, the memory 52 and/or memory element storing the corresponding
operational instructions may be embedded within, or external to, the circuitry
comprising the state machine, analog circuitry, digital circuitry, and/or
logic circuitry.
Further note that, the memory element stores, and the processing module
executes,
hard coded and/or operational instructions corresponding to at least some of
the steps
and/or functions illustrated in Figures 1-4.
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As one of ordinary skill in the art will appreciate, user interface 12
corresponds generally to any user interface within an ophthalmic surgical
system that
employs a surgical laser. In particular, user interface 12 can be used by a
user, such
as a surgeon, to enter/program an embodiment of the pre-defined auto-titration
procedure of the present invention. For example, the user can input via a
graphical
user interface 12 and the other control devices of laser 10 the laser starting
power,
pulse duration, inter-pulse time, power step increments, maximum allowed laser
power, surgical power setting offset from final titration power setting (e.g.,
at
footswitch release), single/multi shot pattern, etc.
FIGURE 2 is a close-up view of one embodiment of a user interface 12 in
accordance with the present invention. At user interface 12, a user can, for
example,
adjust the laser power 30, pulse duration 32 or inter-pulse time 34 by
touching the
screen at the respective function label. The user interface 12 can then, for
example,
bring up a graphical slider (not shown) that the user can use to adjust the
parameter by
sliding his/her finger across the screen in a manner that will be well known
to those
having ordinary skill in the art. The surgeon can thus pre-define a titration
procedure
with the functions shown in FIGURE 2 as well as others (e.g., maximum laser
power,
surgical power offset percentage, etc.). A current, or previously stored
titration
program can then be selected via user interface 12 and activated by the
surgeon by,
for example, activating a laser firing footswitch or other device. A titration
program
can be selected and made ready for activation by the surgeon by placing the
laser 10
in a titration mode, which can be done, for example, by selecting such a mode
at the
user interface 12, for example, by selecting titrate button 40, or by
actuating a
dedicated titration-mode switch 29 of FIGURE 1, a soft switch, or by any other
such
control on the surgical laser 10.
FIGURE 3 is a graphical representation of the power vs. time profile of one
predefined titration program/algorithm in accordance with an embodiment of
this
invention. In the example of graph 100, the surgeon selects, for example, a
starting
laser power of 200 mW, a pulse duration of 200 ms, an inter-pulse time of 200
ms, a
power step increment of 30 mW, a maximum allowed power of 500 mW and a
surgical laser power setting offset from final titration power of -20% (i.e.,
once the
surgeon stops the laser test shots upon observing a desired tissue effect by,
for
example, releasing a footswitch or other actuator, the titration procedure
will
automatically set the surgical laser power at 20% less than the laser power
upon
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footswitch release). The surgeon can program these titration settings at the
laser 10
via the user interface 12 and can, if desired, save the titration settings for
later recall.
As previously discussed, a surgeon can initiate the auto-titration mode by,
for
example, depressing a footswitch, or a button, or virtual button, on a laser
10 console.
As shown in FIGURE 3, at point A, the surgeon presses the actuation mechanism
(e.g., a footswitch) to fire laser 10 and the automatic titration
sequence/algorithm is
initiated and controls the firing of the laser 10 in accordance with the auto-
titration
algorithm/program. From point A to point B the laser power increases in 30 mW
increments every 200 ms and each pulse has a 200 ms duration. At point B, the
surgeon releases the actuator and the laser firing stops. The final, surgical
power
setting is automatically set to 20% less than the power at point B (as shown
at point
C) by the titration algorithm of this invention. Once the power has been
adjusted to
its surgical value, the laser 10 can be automatically transitioned to a
"surgical mode"
(i.e., the auto-titration mode is terminated and the laser is "ready") without
further
input from the surgeon and the laser 10 is ready for surgery. The surgeon can
thus
transition quickly and efficiently to performing the intended surgery with
laser 10
automatically configured to his or her pre-defined power setting and any other
pre-
defined parameter settings. If the surgeon decides that the auto-configured
surgical
power setting is inappropriate for the surgery, he or she can repeat the
procedure
above or adjust the power manually.
FIGURE 4 is a flowchart illustrating the steps of one embodiment of the
method of this invention. At step 200 a user programs and/or selects an auto-
titration
program in a manner as described above. Step 200 can also comprise the user
placing
the surgical laser 10 into a titration-mode as previously described. At step
210, the
user executes the selected auto-titration program by, for example, pressing an
actuation mechanism, such as a footswitch, to fire laser 10 (one or more test
shots to
titrate laser 10). The automatic titration sequence is initiated and controls
the firing of
the laser 10 in accordance with the selected titration program. At step 220,
upon
observing a desired tissue response at the test shot locations, the user stops
the firing
of laser 10 by, for example, releasing the actuation mechanism. At step 230,
in
response to the surgeon's input (deactivating laser), the auto-titration
program
automatically configures selected laser parameters corresponding to the
selected auto-
titration program in accordance with the pre-defined criteria of the auto-
titration
program. At step 240, the laser 10 is transitioned to a "ready" (surgical)
mode, either
automatically by the auto-titration program or via another user input, and, at
step 250,
CA 02592818 2013-06-14
the surgeon can perform the surgical procedure. The surgeon can thus
transition quickly and
efficiently to performing the intended surgery with laser 10 automatically
configured to his
or her pre-defined power setting and any other pre-defined parameter settings.
Embodiments of the method of this invention can comprise some or all of the
steps
described above.
A further embodiment of the present invention can comprise an apparatus for
auto-
titrating a surgical laser. As shown in FIGURE 5, the apparatus 400 can
comprise a
processing module 402 and a memory 404. Processing module 402 may be a single
processing device or a plurality of processing devices. Such a processing
device may be a
microprocessor, micro-controller, digital signal processor, microcomputer,
central
processing unit, field programmable gate array, programmable logic device,
state machine,
logic circuitry, analog circuitry, digital circuitry, and/or any device that
manipulates signals
(analog and/or digital) based on hard coding of the circuitry and/or
operational instructions.
Memory 404 may be a single memory device, a plurality of memory devices,
and/or
embedded circuitry of the processing module. Memory 404 may be a read-only
memory,
random access memory, volatile memory, non-volatile memory, static memory,
dynamic
memory, flash memory, cache memory, and/or any device that stores digital
information.
Note that when the processing module 402 implements one or more of its
functions via a
state machine, analog circuitry, digital circuitry, and/or logic circuitry,
the memory and/or
memory element storing the corresponding operational instructions may be
embedded
within, or external to, the circuitry comprising the state machine, analog
circuitry, digital
circuitry, and/or logic circuitry. Further note that, the memory 404 stores,
and the
processing module 402 executes, hard coded and/or operational instructions
corresponding
to at least some of the steps and/or functions illustrated in Figures 1-4.
The present invention has been described by reference to certain preferred
embodiments; however, it should be understood that it may be embodied in other
specific
forms or variations thereof. As may be used herein, the terms "substantially"
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and "approximately" provides an industry-accepted tolerance for its
corresponding
term and/or relativity between items. Such an industry-accepted tolerance
ranges
from less than one percent to fifty percent and corresponds to, but is not
limited to,
component values, integrated circuit process variations, temperature
variations, rise
and fall times, and/or thermal noise. Such relativity between items ranges
from a
difference of a few percent to magnitude differences. As may also be used
herein, the
term(s) "coupled to" and/or "coupling" and/or includes direct coupling between
items
and/or indirect coupling between items via an intervening item (e.g., an item
includes,
but is not limited to, a component, an element, a circuit, and/or a module)
where, for
indirect coupling, the intervening item does not modify the information of a
signal but
may adjust its current level, voltage level, and/or power level. As may
further be used
herein, inferred coupling (i.e., where one element is coupled to another
element by
inference) includes direct and indirect coupling between two items in the same
manner as "coupled to". As may even further be used herein, the term "operable
to"
indicates that an item includes one or more of power connections, input(s),
output(s),
etc., to perform one or more its corresponding functions and may further
include
inferred coupling to one or more other items. As may still further be used
herein, the
term "associated with", includes direct and/or indirect coupling of separate
items
and/or one item being embedded within another item. As may be used herein, the
term "compares favorably", indicates that a comparison between two or more
items,
signals, etc., provides a desired relationship. For example, when the desired
relationship is that signal 1 has a greater magnitude than signal 2, a
favorable
comparison may be achieved when the magnitude of signal 1 is greater than that
of
signal 2 or when the magnitude of signal 2 is less than that of signal 1.
While the present invention has been described with reference to the general
area of laser ophthalmic surgery, the teachings contained herein can apply
equally to
any surgical system where it is desirous to control a laser subsystem.
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