WO2005079919A1 - A medical laser system and method of irradiating a treatment area - Google Patents

A medical laser system and method of irradiating a treatment area Download PDF

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Publication number
WO2005079919A1
WO2005079919A1 PCT/SG2005/000049 SG2005000049W WO2005079919A1 WO 2005079919 A1 WO2005079919 A1 WO 2005079919A1 SG 2005000049 W SG2005000049 W SG 2005000049W WO 2005079919 A1 WO2005079919 A1 WO 2005079919A1
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WIPO (PCT)
Prior art keywords
image
treatment area
laser
laser system
captured image
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PCT/SG2005/000049
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French (fr)
Inventor
Keng Siang Richard Teo
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Keng Siang Richard Teo
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Publication of WO2005079919A1 publication Critical patent/WO2005079919A1/en

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Classifications

    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61FFILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F9/00Methods or devices for treatment of the eyes; Devices for putting-in contact lenses; Devices to correct squinting; Apparatus to guide the blind; Protective devices for the eyes, carried on the body or in the hand
    • A61F9/007Methods or devices for eye surgery
    • A61F9/008Methods or devices for eye surgery using laser
    • A61F9/00821Methods or devices for eye surgery using laser for coagulation
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61FFILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F9/00Methods or devices for treatment of the eyes; Devices for putting-in contact lenses; Devices to correct squinting; Apparatus to guide the blind; Protective devices for the eyes, carried on the body or in the hand
    • A61F9/007Methods or devices for eye surgery
    • A61F9/008Methods or devices for eye surgery using laser
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00Surgical instruments, devices or methods, e.g. tourniquets
    • A61B2017/00017Electrical control of surgical instruments
    • A61B2017/00022Sensing or detecting at the treatment site
    • A61B2017/00057Light
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B18/18Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves
    • A61B18/20Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves using laser
    • A61B2018/2035Beam shaping or redirecting; Optical components therefor
    • A61B2018/20351Scanning mechanisms
    • A61B2018/20359Scanning mechanisms by movable mirrors, e.g. galvanometric
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61FFILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F9/00Methods or devices for treatment of the eyes; Devices for putting-in contact lenses; Devices to correct squinting; Apparatus to guide the blind; Protective devices for the eyes, carried on the body or in the hand
    • A61F9/007Methods or devices for eye surgery
    • A61F9/008Methods or devices for eye surgery using laser
    • A61F2009/00844Feedback systems
    • A61F2009/00846Eyetracking
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61FFILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F9/00Methods or devices for treatment of the eyes; Devices for putting-in contact lenses; Devices to correct squinting; Apparatus to guide the blind; Protective devices for the eyes, carried on the body or in the hand
    • A61F9/007Methods or devices for eye surgery
    • A61F9/008Methods or devices for eye surgery using laser
    • A61F2009/00861Methods or devices for eye surgery using laser adapted for treatment at a particular location
    • A61F2009/00872Cornea

Definitions

  • This invention relates to a medical laser system and method for irradiating a treatment area, and refers particularly, but not exclusively, to such a laser system for treatment of a part of a body, such as, for example, an eye.
  • the medical laser system may be employed in a field of medicine such as, for example, ophthalmology.
  • Lasers have been employed in the treatment of a wide spectrum of retina pathologies.
  • techniques of laser delivery have not kept pace with advancements in laser technology.
  • the laborious task of firing laser shots to the intended retina region in a piecemeal fashion is still a predominantly manual process.
  • Fig. 1 denotes several current laser delivery methods directly onto a retina 10.
  • the numerals in each circle denotes the order in which laser shots are fired.
  • Fig. 1a denotes consecutive concentric firing of laser shots.
  • Fig. 1b denotes randomised quadrant-ic firing of laser shots while
  • Fig. 1c denotes firing of laser shots using shortest possible routes.
  • Such methods of laser delivery rely on manual aiming techniques and are prone to errors including, for example, mis-hits or over exposure to a laser. This may lead to under-treatment, or charring, both which are highly undesirable.
  • the intensity of a laser should be varied to ensure effective treatment for each affected region.
  • the invention aims to harness these advancements in technology to provide a viable alternative to the automated delivery of laser, in particular, pan retina photocoagulation to the retina.
  • a viable practical solution to the tedious task of laser delivery in diabetic retinopathy may thus be conceivable.
  • This invention may also have significant implications in the various pathologies of the posterior segment of the eye that require therapeutic laser treatment modality.
  • a medical laser system including: a laser source for the generation of a laser beam; an image capturing device for the capture of at least one image of a treatment area; a processing unit for the processing of the at least one captured image to define a plurality of irradiation positions in the treatment area and for control of the laser source; and an illumination apparatus for the illumination of the treatment area.
  • the laser source is operable to irradiate a plurality of positions in the treatment area.
  • the medical laser system may further include an image frame capture apparatus for the storage of the at least one image of a treatment area, each of the at least one image being captured at different times.
  • the captured image is a wide field image.
  • the captured image may be within a range of 1° to 180°. It is more preferable that the captured image is a wide field image ranged between 10° to 170°. It is also preferable that the captured image is a wide field image ranged between 20° to 160°. It may be preferable that the captured image is a wide field image ranged between 30° to 10. 150°. It may be advantageous that the captured image is a wide field image ranged between 40° to 140°. It is most preferable that the captured image is a wide field image ranged between 50° to 130°.
  • the laser system may be for treating an area which is part of an eye. It is preferable that the laser system is for treating a retina in the eye.
  • the laser source is selected from the group consisting of: a solid state laser, a conventional laser, a micropulse laser, a semiconductor laser and a gas laser. It is advantageous that components of the laser source is selected from the group consisting of: low energy tracking beams, and high-energy coagulation0 beams.
  • the image capturing device is selected from the group consisting of: a digital video camera, and an analog video camera. It is also advantageous that the processing unit, automatically defines the plurality of irradiation positions. A user of5 the medical laser system may manually define the plurality of irradiation positions. It is preferable for the processing unit to include a monitor to display the treatment area.
  • the illumination apparatus uses trans sclera illumination0 technique.
  • the illumination light may be introduced to a surface of a sclera using an illuminating ringlight through contact or close proximity to the sclera with an integrated interfacing device such as a hollow shaped object housing a contact lens (which may serve as an eyelid retractor).
  • a separate eyelid retractor may be used to maintain eyelids in a fixed position.
  • the illumination apparatus may include at least one light filter.
  • the medical laser system preferably includes apparatus to adjust the intensity of the laser beam. It is necessary for the medical laser system to include a safety device like a cut-off facility when loss of eye tracking occurs.
  • a method of irradiating a treatment area including: capturing at least one image of a treatment area illuminated by trans sclera illumination; processing the at least one captured image to define a plurality of irradiation positions in the treatment area; activating a laser beam from a laser source; and adjusting the position of the laser beam in accordance with the defined plurality of irradiation positions.
  • the laser beam irradiation of each position in the treatment area may then be carried out.
  • the position of the laser beam may be adjusted automatically or manually defined by a user. It is advantageous that the captured image is a wide view image.
  • the captured image may be within a range of 1° to 180°.
  • the captured image is a wide field image ranged between 10° to 170°. It is also preferable that the captured image is a wide field image ranged between 20° to 160°. It may be preferable that the captured image is a wide field image ranged between 30° to 150°. It may be advantageous that the captured image is a wide field image ranged between 40° to 140°. It is most preferable that the captured image is a wide field image ranged between 50° to 130°. It is most preferable that the captured image is processed frame-by-frame.
  • the treatment area is part of an eye, like the retina.
  • the treatment area may be also be biological tissue.
  • the laser source is selected from the group consisting of: a solid state laser, a conventional laser, a micropulse laser, a semiconductor laser and a gas laser. It is most advantageous that a component of the laser source is selected from the group consisting of: low energy tracking beams, and high-energy coagulation beams.
  • a method of reflectance feedback control including: capturing an image of an irradiated position on biological tissue; and processing the captured image to determine an actual effect of irradiation by a laser to automatically determine whether the irradiation position needs to be further irradiated to achieve a desired irradiation effect.
  • Fig. 1 denotes several current laser delivery methods directly onto a retina
  • Fig. 2 denotes a typical setup of a medical laser system according to a preferred embodiment of the invention
  • Fig. 3 denotes several laser delivery methods directly onto a retina according to a preferred embodiment of the invention
  • Fig. 4 denotes a view of the medical laser system of Fig. 2 at a position close to the eye (showing part of a laser subsystem, an optical relay subsystem and a trans sclera illumination device);
  • Fig. 5 denotes an alternative embodiment of a optical relay subsystem with a laser subsystem incorporated within the optical relay subsystem;
  • Fig. 6 denotes the laser subsystem positioned before the optical relay subsystem along the path of a laser beam
  • Fig. 7 denotes an alternative embodiment of the medical laser system setup with an alternative laser subsystem that delivers the laser beam via the optical relay subsystem without the use of beam splitters;
  • Fig. 8 denotes a flow chart showing an operation of the system of Fig. 2 to treat pathologies of the eye;
  • Fig. 9 denotes a flow chart showing an operation of the system of Fig. 2 for reflectance feedback control
  • Fig. 10 denotes a flow chart showing an operation of the image processing software
  • Fig. 11 denotes a flow chart showing an operation of the video motion tracking software.
  • the system 18 includes an image capturing apparatus 20 such as, for example, a digital video camera or an analog video camera. Images of parts of an eye 21, such as, for example, a retina may be captured by the camera for the purpose of tracking any eye movement. There is also an image frame capture apparatus 22 for the storage of individual frames of the same image at different times.
  • the system 18 includes a processing unit 24, such as, for example, a personal computer or workstation for tracking image frames and for the control of laser delivery.
  • the processing unit 24 may be linked to a monitor 25.
  • the monitor 25 may be used to display the treatment area.
  • the system 18 also includes a laser source 26, such as, for example, solid state, conventional, gas, semicondutor or micropulse lasers for the generation of a laser beam 34.
  • the laser source 26 may include low energy tracking beams.
  • a laser deflection control 28, optical lenses 30 and a beam splitter 40 may be included in the laser system 18 along the path of the laser beam 34.
  • the beam splitter may be a prism in a laser subsystem 32.
  • the laser subsystem 32 may also include lenses to focus the laser beam 34.
  • a trans sclera illumination device 36 may also be positioned in front of an eye 21 for trans sclera illumination of the eye.
  • a light source 37 may provide light 39 for transmission to the device 36 for illumination through a ringlight illuminator with fibre optic ends. The light 39 may be transmitted from source 37 by fibre optic strands/cables to the device 36.
  • the laser deflection control means 28 may be X and Y axis galvanometers with mirrors.
  • the galvanometer-operated mirrors may be controlled by laser guidance software to aid in reflecting the laser beam 34 in two perpendicular planes for quick and accurate positional adjustability of the laser beam 34 onto retina tissue.
  • the medical laser system 18 may be arranged to treat pathologies of the eye, in particular, but not exclusively, the retina (posterior aspect of the eyeball).
  • the system 18 may be arranged to irradiate a treatment area for various ailments, such as, for example, diabetic retinopathic changes, or retinal tears. Different types of lesions may require different respective laser wavelengths, intensities and/or durations in order to achieve the desired therapeutic effect. Therefore the laser 26 includes functions to control these parameters in order to generate a desired laser beam 34 suitable for the required treatment.
  • the laser 26 is equipped with the ability to switch on and off rapidly to successively "fire" at discrete intervals on different irradiation areas under the control of a laser guidance software installed in the processing unit 24.
  • the processing unit 24 is also used to control the functions to adjust the different parameters of the laser beam 34 as described earlier.
  • the laser beam 34 may pass through the optical lenses 30, the laser deflection control means 28, the beam splitter 40 and the trans sclera illumination device 36 as shown in Fig. 2.
  • the optical lenses 30 may be employed to focus, align and direct laser pathways.
  • the beam splitter 40 may be employed to reflect and divert certain wavelengths of laser beams while allowing other wavelengths of laser beams to pass right through.
  • the trans sclera illumination device 36 includes bundles of optic fibers arranged in an annular arrangement for a ring light illuminator effect. Illumination may be introduced to the surface of a sclera through contact with a plastic cone which may be employed as an eyelid retractor. Light filters in the device 36 may be used to vary the quality of pictures taken of the retina.
  • Trans sclera illumination introduces diffuse lighting within the eye 21. Light does not enter directly into the pupil of the eye 21. The reduced light intensity entering the pupil of the eye 21 minimises discomfort felt by patients. Light enters at an angle such that the pupil in eye 21 does not overly dilate and cause discomfort to patients.
  • Wide angle views of the retina may also be capturable if components of wide field optics are incorporated into the illuminator device 36.
  • Wide field optics may be incorporated into the illuminator device 36 to enable the capture of a plurality of images.
  • the captured image may be within a range of 1° to 180°. It is more preferable that the captured image is a wide field image ranged between 10° to 170°. It is also preferable that the captured image is a wide field image ranged between 20° to 160°. It may be preferable that the captured image is a wide field image ranged between 30° to 150°. It may be advantageous that the captured image is a wide field image ranged between 40° to 140°. It is most preferable that the captured image is a wide field image ranged between 50° to 130°.
  • An optical relay subsystem 38 may be incorporated to optimise image quality.
  • the optical relay subsystem 38 is an example of an image quality optimisation component. It comprises a series of lenses 102, focusing devices for depth adjustment, a variable diaphragm aperture (not shown) and other components known in the state of the art for optimization of image quality.
  • the optical relay subsystem 38 may be positioned at the center of the ring light of the trans sclera illumination device 36 (for imaging only) or incorporated with the laser source 26 (to allow imaging, tracking and computed automated delivery of laser shots).
  • the laser source 26 may include various low energy aiming, guiding and tracking beams, and a high-energy coagulation beam.
  • the nature of the laser source 26 may be of any physical state such as, for example, solid state, conventional, gas, semicondutor or micropulse lasers for the generation of a laser beam.
  • the laser system 18 may include devices to control the intensity of the laser beam 34.
  • the image capture apparatus 20 in Figure 2 is arranged to capture an image or images of the retina.
  • the apparatus 20 is a digital camera so that the digital image captured can be immediately transferred to the processing unit 24 for further processing.
  • an analog camera may be used but the image taken may be digitised, for example, by using a digital video card and analog-to- digital conversion software installed in the processing unit 24.
  • the processing unit 24 controls most of the devices of the system 18.
  • the processing unit 24 receives images from the image capture apparatus 20, processes them and uses them to control the laser source 26 and the control means 28.
  • the processing unit 24 has three software components described as follows: a. Image Processing Software Referring to Fig.
  • digital video images or frames may be sent into an image processing software (70) which may comprise a frame grabber program 22 to process each frame of the video image independently.
  • This frame grabber program 22 allows the user to freeze a section of the video to manually highlight or identify in that frame the portion of the retina to be targeted (72).
  • Various drawing tools can be employed to identify treatment area, such as point-to-point mapping, outlining and "magic wand" which can be found in commercial graphics software such as "Adobe Photoshop” or other proprietary software.
  • the borders of the treatment area to be irradiated may then be accurately defined (74).
  • the image processing software may also comprise other algorithms which may be used to calculate the best way to irradiate a portion of the retina (76) with a correct dosage of the laser beam 34 and other parameters, such as, for example, size of the laser beam 34, intensity, scanning frequency.
  • the software may also be able to plot precise coordinates for the laser beam 34 to irradiate a portion of the retina.
  • the software may also calculate the optimal duration of exposure based on the desired beam size and intensity on the portion of the retina.
  • this software may be employed to detect motion of a treatment area relative to the laser beam 34.
  • the software may locate a point of reference (80), for example the optic disc or the geometry of the arterial arcades of an eye, on freeze-frames of the acquired video image. By comparing the differences between consecutive freeze frames, positional changes of the point of reference are tracked (82). The software would then compare the relative position of this point of reference to the original frame on which the coordinates of the irradiation positions, as provided by the image processing software, are denoted. The software is thus able to calculate (84) and track changes in the position of the eye and the irradiation positions in real time. These updated positional coordinates of the irradiation positions are then sent to a laser guidance software (86) to effect firing of the laser 26 on these locations.
  • a point of reference 80
  • the software may locate a point of reference (80), for example the optic disc or the geometry of the arterial arcades of an eye, on freeze-frames of the acquired video image. By comparing the differences between consecutive freeze
  • the laser guidance software processes the inputs and generates outputs to control the laser 26 and the control means 28.
  • This software may be used to control different parameters of the laser 26, such as, for example, the exposure time of each activation of the laser beam 34, intensity of each shot, or the interval between shots.
  • the software program may also be used to control the galvanometers of the laser beam deflection control means 28 to vary the X-Y position of the laser beam 34 to the desired irradiation location.
  • the laser guidance software also controls the exposure of the laser beam . 34 by controlling the activation of the laser 26 according to a desired exposure time. Conventional methods established in the laser industry can be used to perform this.
  • Different therapeutic effects as compared with a continuous laser exposure may be achieved by adjusting the scanning frequency of the laser beam 34.
  • Diffused light from the trans sclera illumination device 36 is reflected off the retina and travels through the pupil.
  • An image is captured by the camera via the optical relay subsystem 38.
  • the laser beam 34 may be activated either automatically or from a user's input to travel through various lenses 30, be reflected via the XY axis galvanometer- operated mirrors 28, beam splitter 40 and lenses in the laser subsystem 32, and trans sclera illumination device 36.
  • the laser beam 34 then travels through the cornea, pupil, lens, vitreous cavity and finally the intended site where coagulation occurs in the retina tissue.
  • a patient will be requested to rest in a preferred position, such as, for example, supine or upright seated position. Subsequently, eye medication may be instilled into the eye to aid in the dilation of the pupil to be operated upon. Local anesthesia may also be applied to the eye and/or its muscles.
  • An eyelid retractor may be used to help keep the eye open and to permit for adequate illumination of the retina.
  • a conical hollow object (housing) 104 which may house a magnifying contact lens and is incorporated within the trans sclera illumination device 36 may serve as an eyelid retractor. Alternatively, a separate eyelid retractor may be used to keep eyelids in a fixed position.
  • a gel may be used as an optical coupling agent at the interface between the cornea and the device used as an eyelid retractor such as the contact lens in the conical hollow object.
  • the trans sclera illumination device 36 may be placed in contact or in close proximity with the eye to be treated with the contact lens acting as an intermediary device.
  • the use of the contact lens in the conical hollow object may restrict random eye movements during the operation procedure.
  • the patient would also be instructed to focus the non-treated eye at a specific target to further reduce unintended eye motion, since bilateral eye movements are usually uniform.
  • the trans sclera illumination technique prevents 'hot spots' from forming in the eye and associated lenses within the optical relay system 38 as incident and reflected light do not travel along the same path.
  • the use of wide field optics also result in a wide field of view of between 50° to 130° of the retina in a single image.
  • the captured image may be within a range of 1° to 180°. It is more preferable that the captured image is a wide field image ranged between 10° to 170°. It is also preferable that the captured image is a wide field image ranged between 20° to 160°. It may be preferable that the captured image is a wide field image ranged between 30° to 150°. It may be advantageous that the captured image is a wide field image ranged between 40° to 140°. It is most preferable that the captured image is a wide field image ranged between 50° to 130°.
  • the resultant image is optimized by the optical relay system 38 (54).
  • the images are then captured in real time by an image capture apparatus 20 and analyzed with the relevant hardware and software (56) such as, for example, frame grabbers with high frame rate analysis on high-performance or high-capacity processors.
  • the images are processed frame-by-frame so as to provide nearly real time information of the position of the retina and thus allow 'instantaneous' tracking of the retina movement. This provides an initial snap shot of the entire retina image.
  • the image is analysed and the processor 24 determines placement of the intended laser shots.
  • the positions of shot placements may also be determined by the user. Regions of the retina to be avoided are evaluated by the operator (58). Final adjustments and checks are made to the intended firing and out-of-bound sites before the information is sent to the laser guidance software.
  • Such information from the laser guidance software is subsequently input to the laser source 26 and XY axis galvanometers operated mirrors 28 (60) so as to accurately place the laser shots at the intended site on the retina.
  • Better frame generation capabilities and processors have resulted in information being generated close to "real-time”.
  • Such updated information may be used to determine the movement of the XY mirrors 28 and the firing of the laser 26 such that the laser 26 would be directed and reflected by the mirrors to the pre-programmed virtual XY axis coordinates on the retina (62).
  • the laser source 26 may consist of a low-power aiming beam for pre-firing evaluation and placement of intended laser shots, and a high power coagulation beam for therapy at the same location on the retina.
  • Infra- red micropulse and other laser parameters may also be incorporated. As such, total reaction and lag time between image capturing and firing of laser shots to the intended retina site would likely be within acceptable clinical requirements to ensure the safety of the procedure for the patient.
  • the laser system 18 may also be employed for reflectance feedback control. The system 18 may be able to consistently control the "whitening" effect caused by the coagulation process on the retina. As each lesion is formed on the retina, the coagulation process produces a 'whitening' effect on the retina that is reflected (90) and observed by the operator on a display on the processing unit 24 (92). The operator has no input.
  • the processor 24 analysis each image and determines the amount and placement of the laser 34. Due to the non-uniform nature of bio-tissue, different regions of the retina would require different amounts of laser energy to produce similar coagulation or "whitening" effects.
  • the intensity of the "whitening” may be fed back in real time by image capturing of the lesion formation and processed by the unit 24. Once the coagulation has reached a predetermined state of "whitening", the laser 26 would stop firing at that specific site and would irradiate the next intended target (94). Thus, uniformity in the coagulation intensity of the various region of the retina may be attainable (96).
  • the entire process of trans sclera illumination, image capturing/tracking, automated delivery of pre determined laser shots to specific sites and reflectance feedback control continues until all intended laser shots are completed.
  • a built-in safety mechanism would be activated to prevent erroneous firing of the laser 26.
  • the aforementioned process would pause until the processing unit 24 manages to relocate (either automatically or manually by the operator) the retina and resume tracking.
  • an infra-red micropulse laser may be employed for the treatment of lesions.
  • Infra-red micropulse lasers have been used in ophthalmology as unintended damage to neighboring tissue may be reduced when such lasers were applied to the retina.
  • a disadvantage of using infra-red micropulse lasers is the emanation of sub-threshold lesions that are not visible to the naked eye.
  • Laser system 18 may be able to capture an image of the retina and assign specific XY coordinates on the retina for laser firing.
  • the formed sub-threshold lesions would not be visible to the naked eye, the computer would be able to 'identify' these treated sites from locations on a coordinate grid. This may allow an operator to keep track of such hidden lesions such that there should not be repeated firing of a laser to a certain position, or missed lesions, thereby allowing complete treatment of affected regions.
  • the method of delivery of the preferred embodiment of the laser system 18 is a result of the need for adequate thermal relaxation, amount of heat dissipation and rate of heat dissipation.
  • such algorithms for controlling the firing and path of laser beam 34 prevent or reduce unintended damage to adjacent healthy retina tissue while the laser shots are delivered to their intended positions on the retina.
  • An operator may have a choice, depending on personal preferences and/or circumstances, to set the processing unit 24 to provide firing sequences such as furthest route possible (Fig. 3a), non - consecutive concentric (Fig. 3b) or consecutive partial 'quadrantic' (Fig. 3c) automated firing of laser shots.
  • the optical relay subsystem 38 may be incorporated with a laser subsystem 32, which may include beam splitters 40 and optical lenses.
  • the optical relay subsystem 38 may be in direct contact or close proxmity with the trans sclera illumination device 36.
  • This arrangement may enable the laser beam 34 to enter the optical relay system 38 through an opening or aperture 37 along an intermediate portion of the optical relay subsystem 38.
  • the laser beam 34 may then be deflected and directed towards the illumination device 36 and the eye.
  • Fig. 6 depicts the laser subsystem 32 alternatively being located prior to the optical relay subsystem 38 in the path of the laser beam 34.
  • Fig. 7 shows the laser subsystem 32 without the use of beam splitters.
  • the laser beam 34 may be directly introduced to the optical relay subsystem 38 without being redirected by any beam splitters.
  • the laser system 18 may also be applicable to biological tissue for cosmetic purposes or other applications.
  • the present invention extends to all features disclosed either individually, or in all possible permutations and combinations.

Abstract

A medical laser system including: a laser source (26) for the generation of a laser beam (34); an image capturing device (20) for the capture of at least one image of a treatment area; a processing unit (24) for the processing of the at least one captured image to define a plurality of irradiation positions in the treatment area and for control of the laser source; and an illumination apparatus (37), for the illumination of the treatment area. The laser source is operable to irradiate a plurality of positions in the treatment area. The illumination apparatus may be a trans-sclera illumination device. A method of irradiating a treatment area and a method for reflectance feedback control are also disclosed.

Description

A Medical Laser System and Method of Irradiating a Treatment Area
Field of Invention
This invention relates to a medical laser system and method for irradiating a treatment area, and refers particularly, but not exclusively, to such a laser system for treatment of a part of a body, such as, for example, an eye. The medical laser system may be employed in a field of medicine such as, for example, ophthalmology.
Background of Invention
Lasers have been employed in the treatment of a wide spectrum of retina pathologies. However, techniques of laser delivery have not kept pace with advancements in laser technology. When treating retina pathologies, the laborious task of firing laser shots to the intended retina region in a piecemeal fashion is still a predominantly manual process.
The long duration and concentration required for the manual delivery of multiple laser shots usually leaves a practitioner fatigued during, and after, the procedure during which hundreds of laser shots may be fired. In addition, the cooperation of a patient to minimise eye movement is paramount to ensure the success of an operation.
Methods of laser delivery have remained unchanged for many years due to limitations of delivery technologies and resistance to change by practitioners. Previous attempts at development of an automated system of laser delivery to the retina have been documented but were never put into practise due to complexities of the process.
Fig. 1 denotes several current laser delivery methods directly onto a retina 10. The numerals in each circle denotes the order in which laser shots are fired. Fig. 1a denotes consecutive concentric firing of laser shots. Fig. 1b denotes randomised quadrant-ic firing of laser shots while Fig. 1c denotes firing of laser shots using shortest possible routes. Such methods of laser delivery rely on manual aiming techniques and are prone to errors including, for example, mis-hits or over exposure to a laser. This may lead to under-treatment, or charring, both which are highly undesirable. As human tissue is not homogeneous, the intensity of a laser should be varied to ensure effective treatment for each affected region.
However, recent advancements in optics, hardware computational rate, tracking software algorithms and more importantly, image capturing systems have now made possible the configuration of a system which integrates the aforementioned components into an automated medical laser delivery system which satisfies clinical requirements and is easily implementable with a relatively low capital outlay.
The invention aims to harness these advancements in technology to provide a viable alternative to the automated delivery of laser, in particular, pan retina photocoagulation to the retina. A viable practical solution to the tedious task of laser delivery in diabetic retinopathy may thus be conceivable. This invention may also have significant implications in the various pathologies of the posterior segment of the eye that require therapeutic laser treatment modality.
Summary of Invention
There is provided a medical laser system including: a laser source for the generation of a laser beam; an image capturing device for the capture of at least one image of a treatment area; a processing unit for the processing of the at least one captured image to define a plurality of irradiation positions in the treatment area and for control of the laser source; and an illumination apparatus for the illumination of the treatment area. Preferably, the laser source is operable to irradiate a plurality of positions in the treatment area. The medical laser system may further include an image frame capture apparatus for the storage of the at least one image of a treatment area, each of the at least one image being captured at different times. There may be an optical relay subsystem for the optimisation of image quality. Preferably, there may be at least one beam deflection device in the medical laser system for the automatic adjustment of the position of the laser beam in accordance with the determined plurality of irradiation positions.
5 It is preferable that the captured image is a wide field image. The captured image may be within a range of 1° to 180°. It is more preferable that the captured image is a wide field image ranged between 10° to 170°. It is also preferable that the captured image is a wide field image ranged between 20° to 160°. It may be preferable that the captured image is a wide field image ranged between 30° to 10. 150°. It may be advantageous that the captured image is a wide field image ranged between 40° to 140°. It is most preferable that the captured image is a wide field image ranged between 50° to 130°. The laser system may be for treating an area which is part of an eye. It is preferable that the laser system is for treating a retina in the eye. It is also preferable to use the laser system for treating biological tissue.5 Preferably, the laser source is selected from the group consisting of: a solid state laser, a conventional laser, a micropulse laser, a semiconductor laser and a gas laser. It is advantageous that components of the laser source is selected from the group consisting of: low energy tracking beams, and high-energy coagulation0 beams.
Preferably, the image capturing device is selected from the group consisting of: a digital video camera, and an analog video camera. It is also advantageous that the processing unit, automatically defines the plurality of irradiation positions. A user of5 the medical laser system may manually define the plurality of irradiation positions. It is preferable for the processing unit to include a monitor to display the treatment area.
It is most preferable that the illumination apparatus uses trans sclera illumination0 technique. The illumination light may be introduced to a surface of a sclera using an illuminating ringlight through contact or close proximity to the sclera with an integrated interfacing device such as a hollow shaped object housing a contact lens (which may serve as an eyelid retractor). Alternatively, a separate eyelid retractor may be used to maintain eyelids in a fixed position. It is advantageous for the illumination apparatus to include at least one light filter. The medical laser system preferably includes apparatus to adjust the intensity of the laser beam. It is necessary for the medical laser system to include a safety device like a cut-off facility when loss of eye tracking occurs.
There is also provided a method of irradiating a treatment area, including: capturing at least one image of a treatment area illuminated by trans sclera illumination; processing the at least one captured image to define a plurality of irradiation positions in the treatment area; activating a laser beam from a laser source; and adjusting the position of the laser beam in accordance with the defined plurality of irradiation positions. The laser beam irradiation of each position in the treatment area may then be carried out. The position of the laser beam may be adjusted automatically or manually defined by a user. It is advantageous that the captured image is a wide view image. The captured image may be within a range of 1° to 180°. It is more preferable that the captured image is a wide field image ranged between 10° to 170°. It is also preferable that the captured image is a wide field image ranged between 20° to 160°. It may be preferable that the captured image is a wide field image ranged between 30° to 150°. It may be advantageous that the captured image is a wide field image ranged between 40° to 140°. It is most preferable that the captured image is a wide field image ranged between 50° to 130°. It is most preferable that the captured image is processed frame-by-frame.
Preferably, the treatment area is part of an eye, like the retina. The treatment area may be also be biological tissue.
It is preferable that the laser source is selected from the group consisting of: a solid state laser, a conventional laser, a micropulse laser, a semiconductor laser and a gas laser. It is most advantageous that a component of the laser source is selected from the group consisting of: low energy tracking beams, and high-energy coagulation beams. There is also provided a method of reflectance feedback control, including: capturing an image of an irradiated position on biological tissue; and processing the captured image to determine an actual effect of irradiation by a laser to automatically determine whether the irradiation position needs to be further irradiated to achieve a desired irradiation effect.
Description of Drawings
In order that the invention may be better understood and readily put into practical effect, there shall now be described by way of non-limitative example only preferred embodiments of the present invention, the description being in reference to the accompanying drawings in which:
Fig. 1 denotes several current laser delivery methods directly onto a retina; Fig. 2 denotes a typical setup of a medical laser system according to a preferred embodiment of the invention;
Fig. 3 denotes several laser delivery methods directly onto a retina according to a preferred embodiment of the invention;
Fig. 4 denotes a view of the medical laser system of Fig. 2 at a position close to the eye (showing part of a laser subsystem, an optical relay subsystem and a trans sclera illumination device);
Fig. 5 denotes an alternative embodiment of a optical relay subsystem with a laser subsystem incorporated within the optical relay subsystem;
Fig. 6 denotes the laser subsystem positioned before the optical relay subsystem along the path of a laser beam;
Fig. 7 denotes an alternative embodiment of the medical laser system setup with an alternative laser subsystem that delivers the laser beam via the optical relay subsystem without the use of beam splitters;
Fig. 8 denotes a flow chart showing an operation of the system of Fig. 2 to treat pathologies of the eye;
Fig. 9 denotes a flow chart showing an operation of the system of Fig. 2 for reflectance feedback control; Fig. 10 denotes a flow chart showing an operation of the image processing software; and Fig. 11 denotes a flow chart showing an operation of the video motion tracking software.
Description of the Preferred Embodiments
Referring to Fig. 2, there is illustrated a medical laser system 18 according to a preferred embodiment of the invention. The system 18 includes an image capturing apparatus 20 such as, for example, a digital video camera or an analog video camera. Images of parts of an eye 21, such as, for example, a retina may be captured by the camera for the purpose of tracking any eye movement. There is also an image frame capture apparatus 22 for the storage of individual frames of the same image at different times. The system 18 includes a processing unit 24, such as, for example, a personal computer or workstation for tracking image frames and for the control of laser delivery. The processing unit 24 may be linked to a monitor 25. The monitor 25 may be used to display the treatment area. The system 18 also includes a laser source 26, such as, for example, solid state, conventional, gas, semicondutor or micropulse lasers for the generation of a laser beam 34. The laser source 26 may include low energy tracking beams.
A laser deflection control 28, optical lenses 30 and a beam splitter 40 may be included in the laser system 18 along the path of the laser beam 34. The beam splitter may be a prism in a laser subsystem 32. The laser subsystem 32 may also include lenses to focus the laser beam 34. A trans sclera illumination device 36 may also be positioned in front of an eye 21 for trans sclera illumination of the eye. A light source 37 may provide light 39 for transmission to the device 36 for illumination through a ringlight illuminator with fibre optic ends. The light 39 may be transmitted from source 37 by fibre optic strands/cables to the device 36.
The laser deflection control means 28 may be X and Y axis galvanometers with mirrors. The galvanometer-operated mirrors may be controlled by laser guidance software to aid in reflecting the laser beam 34 in two perpendicular planes for quick and accurate positional adjustability of the laser beam 34 onto retina tissue.
The medical laser system 18 may be arranged to treat pathologies of the eye, in particular, but not exclusively, the retina (posterior aspect of the eyeball). The system 18 may be arranged to irradiate a treatment area for various ailments, such as, for example, diabetic retinopathic changes, or retinal tears. Different types of lesions may require different respective laser wavelengths, intensities and/or durations in order to achieve the desired therapeutic effect. Therefore the laser 26 includes functions to control these parameters in order to generate a desired laser beam 34 suitable for the required treatment. In addition, the laser 26 is equipped with the ability to switch on and off rapidly to successively "fire" at discrete intervals on different irradiation areas under the control of a laser guidance software installed in the processing unit 24. The processing unit 24 is also used to control the functions to adjust the different parameters of the laser beam 34 as described earlier.
The laser beam 34 may pass through the optical lenses 30, the laser deflection control means 28, the beam splitter 40 and the trans sclera illumination device 36 as shown in Fig. 2. The optical lenses 30 may be employed to focus, align and direct laser pathways. The beam splitter 40 may be employed to reflect and divert certain wavelengths of laser beams while allowing other wavelengths of laser beams to pass right through.
The trans sclera illumination device 36 includes bundles of optic fibers arranged in an annular arrangement for a ring light illuminator effect. Illumination may be introduced to the surface of a sclera through contact with a plastic cone which may be employed as an eyelid retractor. Light filters in the device 36 may be used to vary the quality of pictures taken of the retina. Trans sclera illumination introduces diffuse lighting within the eye 21. Light does not enter directly into the pupil of the eye 21. The reduced light intensity entering the pupil of the eye 21 minimises discomfort felt by patients. Light enters at an angle such that the pupil in eye 21 does not overly dilate and cause discomfort to patients. Wide angle views of the retina may also be capturable if components of wide field optics are incorporated into the illuminator device 36. Wide field optics may be incorporated into the illuminator device 36 to enable the capture of a plurality of images. The captured image may be within a range of 1° to 180°. It is more preferable that the captured image is a wide field image ranged between 10° to 170°. It is also preferable that the captured image is a wide field image ranged between 20° to 160°. It may be preferable that the captured image is a wide field image ranged between 30° to 150°. It may be advantageous that the captured image is a wide field image ranged between 40° to 140°. It is most preferable that the captured image is a wide field image ranged between 50° to 130°. An optical relay subsystem 38 may be incorporated to optimise image quality.
Referring to Fig. 4, the optical relay subsystem 38 is an example of an image quality optimisation component. It comprises a series of lenses 102, focusing devices for depth adjustment, a variable diaphragm aperture (not shown) and other components known in the state of the art for optimization of image quality. The optical relay subsystem 38 may be positioned at the center of the ring light of the trans sclera illumination device 36 (for imaging only) or incorporated with the laser source 26 (to allow imaging, tracking and computed automated delivery of laser shots).
The laser source 26 may include various low energy aiming, guiding and tracking beams, and a high-energy coagulation beam. The nature of the laser source 26 may be of any physical state such as, for example, solid state, conventional, gas, semicondutor or micropulse lasers for the generation of a laser beam. The laser system 18 may include devices to control the intensity of the laser beam 34.
The image capture apparatus 20 in Figure 2 is arranged to capture an image or images of the retina. Preferably, the apparatus 20 is a digital camera so that the digital image captured can be immediately transferred to the processing unit 24 for further processing. Alternatively an analog camera may be used but the image taken may be digitised, for example, by using a digital video card and analog-to- digital conversion software installed in the processing unit 24. The processing unit 24 controls most of the devices of the system 18. The processing unit 24 receives images from the image capture apparatus 20, processes them and uses them to control the laser source 26 and the control means 28. Preferably, the processing unit 24 has three software components described as follows: a. Image Processing Software Referring to Fig. 9, digital video images or frames may be sent into an image processing software (70) which may comprise a frame grabber program 22 to process each frame of the video image independently. This frame grabber program 22 allows the user to freeze a section of the video to manually highlight or identify in that frame the portion of the retina to be targeted (72). Various drawing tools can be employed to identify treatment area, such as point-to-point mapping, outlining and "magic wand" which can be found in commercial graphics software such as "Adobe Photoshop" or other proprietary software. The borders of the treatment area to be irradiated may then be accurately defined (74).
In addition to the frame grabber function, the image processing software may also comprise other algorithms which may be used to calculate the best way to irradiate a portion of the retina (76) with a correct dosage of the laser beam 34 and other parameters, such as, for example, size of the laser beam 34, intensity, scanning frequency. The software may also be able to plot precise coordinates for the laser beam 34 to irradiate a portion of the retina. The software may also calculate the optimal duration of exposure based on the desired beam size and intensity on the portion of the retina.
b. Video Motion Tracking Software.
Referring to Fig. 10, this software may be employed to detect motion of a treatment area relative to the laser beam 34. The software may locate a point of reference (80), for example the optic disc or the geometry of the arterial arcades of an eye, on freeze-frames of the acquired video image. By comparing the differences between consecutive freeze frames, positional changes of the point of reference are tracked (82). The software would then compare the relative position of this point of reference to the original frame on which the coordinates of the irradiation positions, as provided by the image processing software, are denoted. The software is thus able to calculate (84) and track changes in the position of the eye and the irradiation positions in real time. These updated positional coordinates of the irradiation positions are then sent to a laser guidance software (86) to effect firing of the laser 26 on these locations.
Laser Guidance Software
With inputs from the image processing software and, if necessary the motion tracking software, the laser guidance software processes the inputs and generates outputs to control the laser 26 and the control means 28.
This software may be used to control different parameters of the laser 26, such as, for example, the exposure time of each activation of the laser beam 34, intensity of each shot, or the interval between shots. The software program may also be used to control the galvanometers of the laser beam deflection control means 28 to vary the X-Y position of the laser beam 34 to the desired irradiation location.
The laser guidance software also controls the exposure of the laser beam . 34 by controlling the activation of the laser 26 according to a desired exposure time. Conventional methods established in the laser industry can be used to perform this.
Different therapeutic effects as compared with a continuous laser exposure may be achieved by adjusting the scanning frequency of the laser beam 34.
It then becomes possible to deliver repeated, pulsed laser beams to the same spot. Having now described the components that make up the medical laser system 18, by referring to Fig. 8, a preferred operative embodiment of the system 18 will now be described. Diffused light from the trans sclera illumination device 36 is reflected off the retina and travels through the pupil. An image is captured by the camera via the optical relay subsystem 38. After illumination of the intended site on the retina tissue to be irradiated, the laser beam 34 may be activated either automatically or from a user's input to travel through various lenses 30, be reflected via the XY axis galvanometer- operated mirrors 28, beam splitter 40 and lenses in the laser subsystem 32, and trans sclera illumination device 36. The laser beam 34 then travels through the cornea, pupil, lens, vitreous cavity and finally the intended site where coagulation occurs in the retina tissue.
In a first step (50), a patient will be requested to rest in a preferred position, such as, for example, supine or upright seated position. Subsequently, eye medication may be instilled into the eye to aid in the dilation of the pupil to be operated upon. Local anesthesia may also be applied to the eye and/or its muscles. An eyelid retractor may be used to help keep the eye open and to permit for adequate illumination of the retina. A conical hollow object (housing) 104 which may house a magnifying contact lens and is incorporated within the trans sclera illumination device 36 may serve as an eyelid retractor. Alternatively, a separate eyelid retractor may be used to keep eyelids in a fixed position. A gel may be used as an optical coupling agent at the interface between the cornea and the device used as an eyelid retractor such as the contact lens in the conical hollow object.
Subsequently, in step (52), the trans sclera illumination device 36 may be placed in contact or in close proximity with the eye to be treated with the contact lens acting as an intermediary device. The use of the contact lens in the conical hollow object may restrict random eye movements during the operation procedure. In addition, the patient would also be instructed to focus the non-treated eye at a specific target to further reduce unintended eye motion, since bilateral eye movements are usually uniform. The trans sclera illumination technique prevents 'hot spots' from forming in the eye and associated lenses within the optical relay system 38 as incident and reflected light do not travel along the same path. The use of wide field optics also result in a wide field of view of between 50° to 130° of the retina in a single image. The captured image may be within a range of 1° to 180°. It is more preferable that the captured image is a wide field image ranged between 10° to 170°. It is also preferable that the captured image is a wide field image ranged between 20° to 160°. It may be preferable that the captured image is a wide field image ranged between 30° to 150°. It may be advantageous that the captured image is a wide field image ranged between 40° to 140°. It is most preferable that the captured image is a wide field image ranged between 50° to 130°.
Reflected light from the retina travels through the pupil and via the various lenses in the trans sclera illumination device 36, the laser subsystem 32 and the optical relay subsystem 38. The resultant image is optimized by the optical relay system 38 (54). The images are then captured in real time by an image capture apparatus 20 and analyzed with the relevant hardware and software (56) such as, for example, frame grabbers with high frame rate analysis on high-performance or high-capacity processors. The images are processed frame-by-frame so as to provide nearly real time information of the position of the retina and thus allow 'instantaneous' tracking of the retina movement. This provides an initial snap shot of the entire retina image.
The image is analysed and the processor 24 determines placement of the intended laser shots. The positions of shot placements may also be determined by the user. Regions of the retina to be avoided are evaluated by the operator (58). Final adjustments and checks are made to the intended firing and out-of-bound sites before the information is sent to the laser guidance software.
Such information from the laser guidance software is subsequently input to the laser source 26 and XY axis galvanometers operated mirrors 28 (60) so as to accurately place the laser shots at the intended site on the retina. Better frame generation capabilities and processors have resulted in information being generated close to "real-time". Such updated information may be used to determine the movement of the XY mirrors 28 and the firing of the laser 26 such that the laser 26 would be directed and reflected by the mirrors to the pre-programmed virtual XY axis coordinates on the retina (62). The laser source 26 may consist of a low-power aiming beam for pre-firing evaluation and placement of intended laser shots, and a high power coagulation beam for therapy at the same location on the retina. Infra- red micropulse and other laser parameters may also be incorporated. As such, total reaction and lag time between image capturing and firing of laser shots to the intended retina site would likely be within acceptable clinical requirements to ensure the safety of the procedure for the patient. The laser system 18 may also be employed for reflectance feedback control. The system 18 may be able to consistently control the "whitening" effect caused by the coagulation process on the retina. As each lesion is formed on the retina, the coagulation process produces a 'whitening' effect on the retina that is reflected (90) and observed by the operator on a display on the processing unit 24 (92). The operator has no input. The processor 24 analysis each image and determines the amount and placement of the laser 34. Due to the non-uniform nature of bio-tissue, different regions of the retina would require different amounts of laser energy to produce similar coagulation or "whitening" effects.
The intensity of the "whitening" may be fed back in real time by image capturing of the lesion formation and processed by the unit 24. Once the coagulation has reached a predetermined state of "whitening", the laser 26 would stop firing at that specific site and would irradiate the next intended target (94). Thus, uniformity in the coagulation intensity of the various region of the retina may be attainable (96).
In the foregoing description of the preferred embodiments, the entire process of trans sclera illumination, image capturing/tracking, automated delivery of pre determined laser shots to specific sites and reflectance feedback control continues until all intended laser shots are completed. In the event of sudden eye movement or other events leading to loss of tracking of the retina, a built-in safety mechanism would be activated to prevent erroneous firing of the laser 26. The aforementioned process would pause until the processing unit 24 manages to relocate (either automatically or manually by the operator) the retina and resume tracking. In another embodiment of the present invention, an infra-red micropulse laser may be employed for the treatment of lesions. Infra-red micropulse lasers have been used in ophthalmology as unintended damage to neighboring tissue may be reduced when such lasers were applied to the retina. However, a disadvantage of using infra-red micropulse lasers is the emanation of sub-threshold lesions that are not visible to the naked eye. At present, intra-venous solutions are used after such laser procedures to identify the location of sub-threshold lesions. Laser system 18 may be able to capture an image of the retina and assign specific XY coordinates on the retina for laser firing. Although the formed sub-threshold lesions would not be visible to the naked eye, the computer would be able to 'identify' these treated sites from locations on a coordinate grid. This may allow an operator to keep track of such hidden lesions such that there should not be repeated firing of a laser to a certain position, or missed lesions, thereby allowing complete treatment of affected regions.
Referring to Fig. 3, the method of delivery of the preferred embodiment of the laser system 18 is a result of the need for adequate thermal relaxation, amount of heat dissipation and rate of heat dissipation. As such, such algorithms for controlling the firing and path of laser beam 34 prevent or reduce unintended damage to adjacent healthy retina tissue while the laser shots are delivered to their intended positions on the retina. An operator may have a choice, depending on personal preferences and/or circumstances, to set the processing unit 24 to provide firing sequences such as furthest route possible (Fig. 3a), non - consecutive concentric (Fig. 3b) or consecutive partial 'quadrantic' (Fig. 3c) automated firing of laser shots.
Referring to Fig. 5, in an alternative arrangement of the present invention, the optical relay subsystem 38 may be incorporated with a laser subsystem 32, which may include beam splitters 40 and optical lenses. In such an instance, the optical relay subsystem 38 may be in direct contact or close proxmity with the trans sclera illumination device 36. This arrangement may enable the laser beam 34 to enter the optical relay system 38 through an opening or aperture 37 along an intermediate portion of the optical relay subsystem 38. The laser beam 34 may then be deflected and directed towards the illumination device 36 and the eye. Similarly, Fig. 6 depicts the laser subsystem 32 alternatively being located prior to the optical relay subsystem 38 in the path of the laser beam 34. The trans sclera illumination device 36 would still remain in direct contact or close proxmity with the optical relay subsystem 38. Fig. 7 shows the laser subsystem 32 without the use of beam splitters. The laser beam 34 may be directly introduced to the optical relay subsystem 38 without being redirected by any beam splitters.
The laser system 18 may also be applicable to biological tissue for cosmetic purposes or other applications.
Whilst there has been described in the foregoing description preferred embodiments of the present invention, it will be understood by those skilled in the technology concerned that many variations or modifications may be made to details of design or construction without departing from the present invention.
The present invention extends to all features disclosed either individually, or in all possible permutations and combinations.

Claims

Claims
1. A medical laser system including: a laser source for the generation of a laser beam; an image capturing device for the capture of at least one image of a treatment area; a processing unit for the processing of the at least one captured image to define a plurality of irradiation positions in the treatment area and for control of the laser source; and an illumination apparatus for the illumination of the treatment area, whereby the laser source is operable to irradiate a plurality of positions in the treatment area.
2. A medical laser system as claimed in claim 1 , further including an image frame capture apparatus for the storage of the at least one image of a treatment area, each of the at least one image being captured at different times.
3. A medical laser system as claimed in either claim 1 or 2, further including an optical relay subsystem for the optimisation of image quality.
4. A medical laser system as claimed in any one of claims 1 to 3, further including at least one beam deflection device for the automatic adjustment of the position of the laser beam in accordance with the determined plurality of irradiation positions.
5. A medical laser system as claimed in any one of claims 1 to 4, wherein the captured image is a wide field image.
6. A medical laser system as claimed in claim 5, wherein the captured image is a wide field image ranged between 1 ° to 180°.
7. A medical laser system as claimed in claim 6, wherein the captured image is a wide field image ranged between 10° to 1 0°.
8. A medical laser system as claimed in claim 7, wherein the captured image is a wide field image ranged between 20° to 160°.
9. A medical laser system as claimed in claim 8, wherein the captured image is a wide field image ranged between 30° to 150°.
10. A medical laser system as claimed in claim 9, wherein the captured image is a wide field image ranged between 40° to 140°.
11. A medical laser system as claimed in claim 10, wherein the captured image is a wide field image ranged between 50° to 130°.
12. A medical laser system as claimed in any one of claims 1 to 11 , wherein the laser system is for treating an area which is part of an eye.
13. A medical laser system as claimed in claim 12, wherein the laser system is for treating a retina in the eye.
14. A medical laser system as claimed in any one of claims 1 to 11 , wherein the laser system is for treating biological tissue.
15. A medical laser system as claimed in any one of claims 1 to 14, wherein the laser source is selected from the group consisting of: a solid state laser, a conventional laser, a micropulse laser, a semiconductor laser and a gas laser.
16. A medical laser system as claimed in claim 15, wherein a component of the laser source is selected from the group consisting of: low energy tracking beams, and high-energy coagulation beams.
17. A medical laser system as claimed in any one of claims 1 to 16, wherein the image capturing device is selected from the group consisting of: a digital video camera, and an analog video camera.
18. A medical laser system as claimed in any one of claims 1 to 17, wherein the processing unit automatically defines the plurality of irradiation positions.
19. A medical laser system as claimed in any one of claims 1 to 17, wherein a user of the medical laser system manually defines the plurality of irradiation positions.
20. A medical laser system as claimed in any one of claims 1 to 19, wherein the processing unit includes a monitor to display the treatment area.
21. A medical laser system as claimed in any one of claims 1 to 20, wherein the illumination apparatus uses trans sclera illumination technique.
22. A medical laser system as claimed claim 21, wherein illumination light is introduced to a surface of a sclera using an illuminating ringlight through contact with an eye with an interfacing device selected from the group consisting of: an eyelid retractor, and a hollow shaped housing with a contact lens.
23. A medical laser system as claimed claim 21, wherein illumination light is introduced to a surface of a sclera using an illuminating ringlight in close proximity with an eye with an interfacing device selected from the group consisting of: an eyelid retractor, and a hollow shaped housing with a contact lens.
24. A medical laser system as claimed in any one of claims 1 to 23, wherein the illumination apparatus includes at least one light filter.
25. A medical laser system as claimed in any one of claims 1 to 24, further including apparatus to adjust the intensity of the laser beam.
26. A medical laser system as claimed in any of the preceding claims, further including a safety device.
27. A medical laser system as claimed claim 26, wherein the safety device is a cut-off facility when loss of eye tracking occurs.
28. A method of irradiating a treatment area, including: capturing at least one image of a treatment area illuminated by trans sclera illumination; processing the at least one captured image to define a plurality of irradiation positions in the treatment area; activating a laser beam from a laser source; and adjusting the position of the laser beam in accordance with the defined plurality of irradiation positions; wherein the laser beam irradiation of each position in the treatment area is carried out.
29. A method of irradiating a treatment area as claimed in claim 28, wherein the position of the laser beam is adjusted automatically.
30. A method of irradiating a treatment area as claimed in claim 28, wherein the position of the laser beam is manually defined by a user.
31. A method of irradiating a treatment area as claimed in any one of claims 28 to 30, wherein the captured image is a wide view image.
32. A method of irradiating a treatment area as claimed in claim 31 , wherein the captured image is a wide view image of a range of 1° to 180°.
33. A method of irradiating a treatment area as claimed in claim 32, wherein the captured image is a wide view image of a range of 10° to 170°.
34. A method of irradiating a treatment area as claimed in claim 33, wherein the captured image is a wide view image of a range of 20° to 160°.
35. A method of irradiating a treatment area as claimed in claim 34, wherein the captured image is a wide view image of a range of 30° to 150°.
36. A method of irradiating a treatment area as claimed in claim 35, wherein the captured image is a wide view image of a range of 40° to 140°.
37. A method of irradiating a treatment area as claimed in claim 36, wherein the captured image is a wide view image of a range of 50° to 130°.
38. A method of irradiating a treatment area as claimed in any one of claims 28 to 37, wherein the captured image is processed frame-by-frame.
39. A method of irradiating a treatment area as claimed in any one of claims 28 to 38, wherein the treatment area is part of an eye.
40. A method of irradiating a treatment area as claimed in claim 39, wherein the treatment area is a retina.
41. A method of irradiating a treatment area as claimed in any one of claims 28 to 38, wherein the treatment area is biological tissue.
42. A method of irradiating a treatment area as claimed in any one of claims 28 to 41, wherein the laser source is selected from the group consisting of: a solid state laser, a conventional laser, a micropulse laser, a semiconductor laser and a gas laser.
43. A method of irradiating a treatment area as claimed in claim 42, wherein a component of the laser source is selected from the group consisting of: low energy tracking beams, and high-energy coagulation beams.
44. A method of reflectance feedback control, including: capturing an image of an irradiated position on biological tissue; and processing the captured image to determine an actual effect of irradiation by a laser to automatically determine whether the irradiation position needs to be further irradiated to achieve a desired irradiation effect.
45. A method of reflectance feedback control as claimed in claim 44, wherein the captured image is a wide view image.
46. A method of reflectance feedback control as claimed in claim 45, wherein the captured image is a wide view image of a range of 1° to 180°.
47. A method of reflectance feedback control as claimed in claim 46, wherein the captured image is a wide view image of a range of 10° to 170°.
48. A method of reflectance feedback control as claimed in claim 47, wherein the captured image is a wide view image of a range of 20° to 160°.
49. A method of reflectance feedback control as claimed in claim 48, wherein the captured image is a wide view image of a range of 30° to 150°.
50. A method of reflectance feedback control as claimed in claim 49, wherein the captured image is a wide view image of a range of 40° to 140°.
51. A method of reflectance feedback control as claimed in claim 50, wherein the captured image is a wide view image of a range of 50° to 130°.
52. A method of irradiating a treatment area using the laser system as claimed in any one of claims 1 to 27.
53. A laser system used for a method of irradiating a treatment area as claimed in any one of claims 28 to 43.
54. A laser system used for a method of reflectance feedback control as claimed in any one of claims 44 to 51.
PCT/SG2005/000049 2004-02-19 2005-02-18 A medical laser system and method of irradiating a treatment area WO2005079919A1 (en)

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SG200400776-1 2004-02-19
SG200400776 2004-02-19

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WO2007059814A2 (en) 2005-11-23 2007-05-31 Carl Zeiss Meditec Ag Device and method for photocoagulation of the retina
WO2010059997A1 (en) * 2008-11-21 2010-05-27 Government Of The United States Of America, As Represented By The Secretary Of The Army Computer controlled system for laser energy delivery to the retina
EP3254730A4 (en) * 2015-05-20 2018-11-07 ZWXG (Beijing) Technology Co., Ltd Imaging dot matrix laser treatment instrument
CN112137716A (en) * 2020-08-24 2020-12-29 苏州科医世凯半导体技术有限责任公司 Light irradiation device, method and storage medium for surface tissue treatment
CN113616934A (en) * 2021-08-24 2021-11-09 北京理工大学 Laser accurate irradiation system and method for photodynamic therapy

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WO2007059814A2 (en) 2005-11-23 2007-05-31 Carl Zeiss Meditec Ag Device and method for photocoagulation of the retina
WO2007059814A3 (en) * 2005-11-23 2008-08-28 Zeiss Carl Meditec Ag Device and method for photocoagulation of the retina
DE102005055885B4 (en) 2005-11-23 2019-03-28 Carl Zeiss Meditec Ag Device for photocoagulation of the retina
WO2010059997A1 (en) * 2008-11-21 2010-05-27 Government Of The United States Of America, As Represented By The Secretary Of The Army Computer controlled system for laser energy delivery to the retina
US8433117B2 (en) 2008-11-21 2013-04-30 The United States Of America As Represented By The Secretary Of The Army Computer controlled system for laser energy delivery to the retina
EP3254730A4 (en) * 2015-05-20 2018-11-07 ZWXG (Beijing) Technology Co., Ltd Imaging dot matrix laser treatment instrument
CN112137716A (en) * 2020-08-24 2020-12-29 苏州科医世凯半导体技术有限责任公司 Light irradiation device, method and storage medium for surface tissue treatment
CN113616934A (en) * 2021-08-24 2021-11-09 北京理工大学 Laser accurate irradiation system and method for photodynamic therapy
CN113616934B (en) * 2021-08-24 2022-11-22 北京理工大学 Laser accurate irradiation system for photodynamic therapy

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