News Column

"System and Method for Determining Dosimetry in Ophthalmic Photomedicine" in Patent Application Approval Process

September 4, 2014



By a News Reporter-Staff News Editor at Politics & Government Week -- A patent application by the inventors PALANKER, Daniel V. (Sunnyvale, CA); ANDERSEN, Dan (Menlo Park, CA), filed on April 17, 2014, was made available online on August 21, 2014, according to news reporting originating from Washington, D.C., by VerticalNews correspondents.

This patent application is assigned to Topcon Medical Laser Systems, Inc.

The following quote was obtained by the news editors from the background information supplied by the inventors: "Laser photomedicine is a well-established therapeutic modality for a wide variety of conditions. To date, the use of ophthalmic lasers has been limited to either short (around one microsecond or shorter) pulse systems for sub-cellular targeting, or long (hundreds of microseconds and longer) pulse systems that indiscriminately denature relatively large volumes of tissue.

"For example, present standard retinal photocoagulative treatment for conditions such as Diabetic Retinopathy, and Age-Related Macular Degeneration utilize visible laser light with exposure durations on the order of 100 ms. Generation of heat due to absorption of visible laser light occurs predominantly in the retinal pigmented epithelium (RPE) and pigmented choriocappilaris, the melanin containing layers directly beneath the photoreceptors of the sensory retina. The RPE is disposed between the sensory retina and the choroid. Due to heat diffusion during long exposures, this standard therapy also irreversibly damages the overlying sensory retina.

"Although it does halt the progress of the underlying disease, such irreversible damage decreases the patient's vision by destroying not only the photoreceptors in the irradiated portion of the retina but also by creating permanent micro-scotomas, and possibly also damaging the retinal nerve fibers that traverse the targeted portion of the retina, creating a defect called arc scotoma. Such nerve fiber damage eliminates the signals it would have carried from distal areas of the retina, thus unnecessarily further worsening the patient's vision.

"To address these issues, systems and methods for creating spatially confined photothermal lesions in ocular tissues have been proposed, such as in co-pending U.S. patent application Ser. No. 11/606,451, which is incorporated herein by reference. However, what is lacking in such systems and methods is a means for gauging a patient's idiosyncratic response and for reliable delivery of the treatment light to create lesions in response thereto.

"Due to strong variability of the retinal absorption, ocular transmission of light, and choroidal blood perfusion, the laser-induced retinal temperature rise strongly varies from patient to patient, and even from location to location in a single patient. So, a global parameter setting for a desired clinical result is not ideal. Left uncorrected, these differences can lead to inhomogeneous treatments, over-treating in some areas and under-treating in others. Physicians have traditionally determined the appropriate treatment for each patient (and even for different areas in the retina of the same patient) by a 'trial and error' approach, which takes a significant amount of time and is entirely qualitative.

"Accordingly, there is a need for a rapid, robust, and cost-effective system and method for providing predictable ophthalmic photomedical treatment such as, but not limited to, the retina and trabecular meshwork, that is not provided by known methods or devices."

In addition to the background information obtained for this patent application, VerticalNews journalists also obtained the inventors' summary information for this patent application: "The present invention solves the aforementioned problems by providing a system and method for treating ophthalmic target tissue using a 'dosimetry pattern' of light of varying pulse durations, spot sizes and/or power densities to efficiently determine the photothermal target properties, and provide more predictable treatment results. The dosimetry pattern may be a plurality of fixed spots, one or more continuous scans resulting in one or more straight or curved line segments, or a combination of both. By locating the region within the dosimetry pattern that provides a visible lesion of a desirable character, or extrapolating such a region, the operating physician may then choose the appropriate system parameters for a given treatment. Alternately, the photomedical system may incorporate an imaging system that identifies the lesions within the dosimetry pattern with the desired clinical results, and adjusts the system parameters in an automated fashion.

"A system for treating ophthalmic target tissue includes a light source for generating a beam of light, a beam delivery unit for delivering the beam of light to ophthalmic target tissue, wherein the beam delivery unit includes a scanner unit for deflecting the beam of light, a controller for controlling at least one of the light source and the beam delivery unit to create a dosimetry pattern of the beam of light on the ophthalmic target tissue for which at least one dosage parameter of the beam of light varies within the dosimetry pattern, and a visualization device for capturing an image of lesions formed on the ophthalmic target tissue by the dosimetry pattern. The controller is configured to control at least one of the light source and the beam delivery unit to then deliver the beam of light to the ophthalmic target tissue having at least one dosage parameter thereof selected in response to the captured image of lesions.

"A method of treating ophthalmic target tissue includes generating a beam of light, delivering the beam of light to ophthalmic target tissue using a scanner unit for deflecting the beam of light, creating a dosimetry pattern of the beam of light on the ophthalmic target tissue for which at least one dosage parameter of the beam of light varies within the dosimetry pattern, capturing an image of lesions formed on the ophthalmic target tissue by the dosimetry pattern, selecting at least one dosage parameter for the beam of light in response to the captured image of lesions, and delivering the beam of light to the ophthalmic target tissue having the selected at least one dosage parameter.

"In another aspect, a system for treating ophthalmic target tissue includes a light source for generating a beam of light, a beam delivery unit for delivering the beam of light to ophthalmic target tissue, wherein the beam delivery unit includes a scanner unit for deflecting the beam of light, a controller for controlling at least one of the light source and the beam delivery unit to create a dosimetry pattern of the beam of light on the ophthalmic target tissue for which at least one dosage parameter of the beam of light varies within the dosimetry pattern, a visualization apparatus for observing lesions formed on the ophthalmic target tissue by the dosimetry pattern, and a user interface for receiving information about the observed lesions. The controller is configured to control at least one of the light source and the beam delivery unit to then deliver the beam of light to the ophthalmic target tissue having at least one dosage parameter thereof selected in response to the received information.

"In yet one more aspect, a method for treating ophthalmic target tissue includes generating a beam of light using a light source, delivering the beam of light to ophthalmic target tissue using a beam delivery unit having a scanner unit for deflecting the beam of light, creating a dosimetry pattern of the beam of light on the ophthalmic target tissue for which at least one dosage parameter of the beam of light varies within the dosimetry pattern, observing lesions formed on the ophthalmic target tissue by the dosimetry pattern, entering information about the observed lesions using a user interface that is connected to a controller that controls at least one of the light source and the beam delivery unit, selecting at least one dosage parameter for the beam of light in response to the entered information, and controlling at least one of the light source and the beam delivery unit using the controller to then deliver the beam of light to the ophthalmic target tissue having the at least one selected dosage parameter.

"Other objects and features of the present invention will become apparent by a review of the specification, claims and appended figures.

BRIEF DESCRIPTION OF THE DRAWINGS

"FIG. 1 is a schematic diagram illustrating a system for retinal treatment.

"FIG. 2 is a schematic diagram illustrating an alternate embodiment of the system of FIG. 1, specifically for trabecular meshwork treatment.

"FIG. 3 is a schematic diagram illustrating an embodiment of the dosimetry pattern formed by discrete pulses.

"FIG. 4 is a schematic diagram illustrating an alternate embodiment of the dosimetry pattern formed by a continuous scan.

"FIG. 5 is a system GUI display indicator that indicates the character of the lesion based upon the results of the dosimetry pattern and selected pulse parameters.

"FIG. 6 is an alternate embodiment of the system GUI display indicator, based upon the ongoing results of the treatment.

"FIG. 7 is an alternate embodiment of the system GUI display indicator for selecting the spatial selectivity of the lesion, based upon the results of the dosimetry pattern.

"FIG. 8 is a schematic diagram showing the use of visible fiducial lesions to indicate the boundary of a pattern of ophthalmoscopically invisible lesions."

URL and more information on this patent application, see: PALANKER, Daniel V.; ANDERSEN, Dan. System and Method for Determining Dosimetry in Ophthalmic Photomedicine. Filed April 17, 2014 and posted August 21, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=1291&p=26&f=G&l=50&d=PG01&S1=20140814.PD.&OS=PD/20140814&RS=PD/20140814

Keywords for this news article include: Topcon Medical Laser Systems Inc.

Our reports deliver fact-based news of research and discoveries from around the world. Copyright 2014, NewsRx LLC


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Source: Politics & Government Week


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