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von der Burchard C, Miura Y, Stanzel B, Chhablani J, Roider J, Framme C, Brinkmann R, Tode J. Regenerative Retinal Laser and Light Therapies (RELITE): Proposal of a New Nomenclature, Categorization, and Trial Reporting Standard. Lasers Surg Med 2024; 56:693-708. [PMID: 39210705 DOI: 10.1002/lsm.23833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Revised: 05/25/2024] [Accepted: 08/02/2024] [Indexed: 09/04/2024]
Abstract
OBJECTIVES Numerous laser and light therapies have been developed to induce regenerative processes in the choroid/retinal pigment epithelium (RPE)/photoreceptor complex, leaving the neuroretina undamaged. These therapies are applied to the macula for the treatment of various diseases, most prominently diabetic maculopathy, retinal vein occlusion, central serous chorioretinopathy, and age-related macular degeneration. However, the abundance of technologies, treatment patterns, and dosimetry protocols has made understanding these therapies and comparing different approaches increasingly complex and challenging. To address this, we propose a new nomenclature system with a clear categorization that will allow for better understanding and comparability between different laser and light modalities. We propose this nomenclature system as an open standard that may be adapted in future toward new technical developments or medical advancements. METHODS A systematic literature review of reported macular laser and light therapies was conducted. A categorization into a standardized system was proposed and discussed among experts and professionals in the field. This paper does not aim to assess, compare, or evaluate the efficacy of different laser or dosimetry techniques or treatment patterns. RESULTS The literature search yielded 194 papers describing laser techniques, 50 studies describing dosimetry, 272 studies with relevant clinical trials, and 82 reviews. Following the common therapeutic aim, we propose "regenerative retinal laser and light therapies (RELITE)" as the general header. We subdivided RELITE into four main categories that refer to the intended physical and biochemical effects of temperature increase (photothermal therapy, PTT), RPE regeneration (photomicrodisruption therapy, PMT), photochemical processes (photochemical therapy, PCT), and photobiomodulation (photobiomodulation therapy, PBT). Further, we categorized the different dosimetry approaches and treatment regimens. We propose the following nomenclature system that integrates the most important parameters to enable understanding and comparability: Pattern-Dosimetry-Exposure Time/Frequency, Duty Cycle/Irradiation Diameter/Wavelength-Subcategory-Category. CONCLUSION Regenerative retinal laser and light therapies are widely used for different diseases and may become valuable in the future. A precise nomenclature system and strict reporting standards are needed to allow for a better understanding, reproduceable and comparable clinical trials, and overall acceptance. We defined categories for a systematic therapeutic goal-based nomenclature to facilitate future research in this field.
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Affiliation(s)
- Claus von der Burchard
- Department of Ophthalmology, University of Kiel, University Medical Center of Schleswig-Holstein, Kiel, Germany
| | - Yoko Miura
- Institute of Biomedical Optics, University of Luebeck, Luebeck, Germany
- Department of Ophthalmology, University of Luebeck, University Medical Center of Schleswig-Holstein, Luebeck, Germany
| | - Boris Stanzel
- Eye Clinic Sulzbach, Knappschaft Hospital Saar, Sulzbach, Germany
| | - Jay Chhablani
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Johann Roider
- Department of Ophthalmology, University of Kiel, University Medical Center of Schleswig-Holstein, Kiel, Germany
| | - Carsten Framme
- Hannover Medical School, University Eye Clinic, Hannover, Germany
| | - Ralf Brinkmann
- Institute of Biomedical Optics, University of Luebeck, Luebeck, Germany
- Medical Laser Center Luebeck, Luebeck, Germany
| | - Jan Tode
- Hannover Medical School, University Eye Clinic, Hannover, Germany
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Kleyman V, Eggert S, Schmidt C, Schaller M, Worthmann K, Brinkmann R, Müller MA. Model Predictive Temperature Control for Retinal Laser Treatments. Transl Vis Sci Technol 2024; 13:28. [PMID: 39330984 PMCID: PMC11437707 DOI: 10.1167/tvst.13.9.28] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Accepted: 08/07/2024] [Indexed: 09/28/2024] Open
Abstract
Purpose Manual, individual adjustment of the laser power in retinal laser therapies is time-consuming, is inaccurate with respect to uniform effects, and can only prevent over- or undertreatment to a limited extent. Automatic closed-loop temperature control allows for similar temperatures at each irradiated spot despite varying absorption. This is of crucial importance for subdamaging hyperthermal treatments with no visible effects and the safety of photocoagulation with short irradiation times. The aim of this work is to perform extensive experiments on porcine eye explants to demonstrate the benefits of automatic control in retinal laser treatments. Methods To ensure a safe and reliable temperature rise, we utilize a model predictive controller. For model predictive control, the current state and the spot-dependent absorption coefficients are estimated by an extended Kalman filter (EKF). Therein, optoacoustic measurements are used to determine the temperature rise at the irradiated areas in real time. We use fluorescence vitality stains to measure the lesion size and validate the proposed control strategy. Results By comparing the lesion size with temperature values for cell death, we found that the EKF accurately estimates the peak temperature. Furthermore, the proposed closed-loop control scheme works reliably with regard to similar lesion sizes despite varying absorption with a smaller spread in lesion size compared to open-loop control. Conclusions Our closed-loop control approach enables a safe subdamaging treatment and lowers the risk for over- and undertreatment for mild coagulations in retinal laser therapies. Translational Relevance We demonstrate that modern control strategies have the potential to improve retinal laser treatments for several diseases.
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Affiliation(s)
- Viktoria Kleyman
- Leibniz University Hannover, Institute of Automatic Control, Hannover, Germany
| | - Sophie Eggert
- University of Lübeck, Institute of Biomedical Optics, Lübeck, Germany
| | | | - Manuel Schaller
- Technische Universität Ilmenau, Institute of Mathematics, Ilmenau, Germany
| | - Karl Worthmann
- Technische Universität Ilmenau, Institute of Mathematics, Ilmenau, Germany
| | - Ralf Brinkmann
- University of Lübeck, Institute of Biomedical Optics, Lübeck, Germany
- Medical Laser Center Lübeck, Lübeck, Germany
| | - Matthias A. Müller
- Leibniz University Hannover, Institute of Automatic Control, Hannover, Germany
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Pope NJ, Denton ML. Differential effects of 808-nm light on electron transport chain enzymes in isolated mitochondria: Implications for photobiomodulation initiation. Mitochondrion 2023; 68:15-24. [PMID: 36371074 DOI: 10.1016/j.mito.2022.11.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Revised: 10/06/2022] [Accepted: 11/04/2022] [Indexed: 11/10/2022]
Abstract
Photobiomodulation is a term for using low-power red to near-infrared light to stimulate a variety of positive biological effects. Though the scientific and clinical acceptance of PBM as a therapeutic intervention has increased dramatically in recent years, the molecular underpinnings of the effect remain poorly understood. The putative chromophore for PBM effects is cytochrome c oxidase. It is postulated that light absorption at cytochrome c oxidase initiates a signaling cascade involving ATP and generation of reactive oxygen species (ROS), which subsequently results in improved cellular robustness. However, this hypothesis is largely based on inference and indirect evidence, and the precise molecular mechanisms that govern how photon absorption leads to these downstream effects remain poorly understood. We conducted low-power PBM-type light exposures of isolated mitochondria to 808 nm NIR light, at a number of irradiances. NIR exposure was found to enhance the activity of complex IV, depress the activity of complex III, and had no effect on the activity of complex II. Further, examining the dose-response of complex IV we found NIR enhancement did not exhibit irradiance reciprocity, indicating the effect on complex IV may not have direct photochemical basis. In summary, this research presents a novel method to interrogate the earliest stages of PBM in the mitochondria, and a unique window into the corresponding molecular mechanism(s) of induction.
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Affiliation(s)
| | - Michael L Denton
- Air Force Research Laboratory, Bioeffects Division, JBSA Fort Sam Houston, TX 78234, United States.
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Miura Y, Inagaki K, Hutfilz A, Seifert E, Schmarbeck B, Murakami A, Ohkoshi K, Brinkmann R. Temperature Increase and Damage Extent at Retinal Pigment Epithelium Compared between Continuous Wave and Micropulse Laser Application. Life (Basel) 2022; 12:life12091313. [PMID: 36143352 PMCID: PMC9504342 DOI: 10.3390/life12091313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 08/14/2022] [Accepted: 08/18/2022] [Indexed: 11/16/2022] Open
Abstract
Continuous wave (CW) and microsecond pulse (MP) laser irradiations were compared regarding cell damage and laser-induced temperature rise at retinal pigment epithelium (RPE). The RPE of porcine RPE-choroid-sclera explants was irradiated with a 577 nm laser in CW or MP mode (5% or 15% duty cycle (DC)) for 20 ms or 200 ms at an average laser power of 20−90 mW. Cell viability was investigated with calcein-AM staining. Optoacoustic (OA) technique was employed for temperature measurement during irradiation. For 200 ms irradiation, the dead cell area (DCA) increased linearly (≈1600 µm2/mW) up to the average power of 40 mW for all modes without significant difference. From 50 mW, the increase of DCA of MP-5% significantly dropped to 610 µm2/mW (p < 0.05), likely due to the detected microbubble formation. OA temperature measurement showed a monotonic temperature increase in CW mode and a stepwise increase in MP mode, but no significant difference in the average temperature increase at the same average power, consistent with the temperature modeling. In conclusion, there is no difference in the average temperature rise between CW and MP modes at the same average power regardless of DC. At lower DC, however, more caution is required regarding mechanical damage due to microbubble formation.
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Affiliation(s)
- Yoko Miura
- Institute of Biomedical Optics, University of Lübeck, 23562 Lübeck, Germany
- Medical Laser Center Lübeck, 23562 Lübeck, Germany
- Department of Ophthalmology, University of Lübeck, 23562 Lübeck, Germany
- Correspondence: ; Tel.: +49-451-3101-3212; Fax: +49-451-3101-3204
| | - Keiji Inagaki
- Inagaki Eye Clinic, Chiba 279-0011, Japan
- Department of Ophthalmology, Faculty of Medicine, Juntendo University, Tokyo 113-8421, Japan
| | | | - Eric Seifert
- Medical Laser Center Lübeck, 23562 Lübeck, Germany
| | | | - Akira Murakami
- Department of Ophthalmology, Faculty of Medicine, Juntendo University, Tokyo 113-8421, Japan
| | - Kishiko Ohkoshi
- Department of Ophthalmology, Hiroo Hanezawa Internal Medicine and Ophthalmology Clinic, Tokyo 150-0012, Japan
- Department of Ophthalmology, St. Luke’s International Hospital, Tokyo 104-8560, Japan
| | - Ralf Brinkmann
- Institute of Biomedical Optics, University of Lübeck, 23562 Lübeck, Germany
- Medical Laser Center Lübeck, 23562 Lübeck, Germany
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5
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Seifert E, Sonntag SR, Kleingarn P, Theisen-Kunde D, Grisanti S, Birngruber R, Miura Y, Brinkmann R. Investigations on Retinal Pigment Epithelial Damage at Laser Irradiation in the Lower Microsecond Time Regime. Invest Ophthalmol Vis Sci 2021; 62:32. [PMID: 33755044 PMCID: PMC7991964 DOI: 10.1167/iovs.62.3.32] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Purpose New lasers with a continuous wave power exceeding 15 W are currently investigated for retinal therapies, promising highly localized effects at and close to the Retinal Pigment Epithelium (RPE). The goal of this work is to evaluate mechanisms and thresholds for RPE cell damage by means of pulse durations up to 50 µs. Methods A diode laser with a wavelength of 514 nm, a power of 15 W, and adjustable pulse durations between 2 µs and 50 µs was used. Porcine RPE-choroidal explants (ex vivo) and chinchilla bastard rabbits (in vivo) were irradiated to determine threshold radiant exposures for RPE damage H¯Cell by calcein vitality staining and fluorescence angiography, respectively. Thresholds for microbubble formation (MBF) H¯MBF were evaluated by time-resolved optoacoustics. Exemplary histologies support the findings. Results H¯MBF
is significantly higher than H¯Cell at pulse durations ≥ 5 µs (P < 0.05) ex vivo, while at 2 µs, no statistically significant difference was found. The ratios between H¯MBF and H¯Cell increase with pulse duration from 1.07 to 1.48 ex vivo and 1.1 to 1.6 in vivo, for 5.2 and 50 µs. Conclusions Cellular damage with and without MBF related disintegration are both present and very likely to play a role for pulse durations ≥ 5 µs. With the lower µs pulses, selective RPE disruption might be possible, while higher values allow achieving spatially limited thermal effects without MBF. However, both modi require a very accurate real-time dosing control in order to avoid extended retinal disintegration in this power range.
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Affiliation(s)
| | | | | | | | | | - Reginald Birngruber
- Medical Laser Center Lübeck, Lübeck, Germany.,Institute of Biomedical Optics, University of Lübeck, Lübeck, Germany
| | - Yoko Miura
- Department of Ophthalmology, University of Lübeck, Lübeck, Germany.,Institute of Biomedical Optics, University of Lübeck, Lübeck, Germany
| | - Ralf Brinkmann
- Medical Laser Center Lübeck, Lübeck, Germany.,Institute of Biomedical Optics, University of Lübeck, Lübeck, Germany
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Adams WR, Mehl B, Lieser E, Wang M, Patton S, Throckmorton GA, Jenkins JL, Ford JB, Gautam R, Brooker J, Jansen ED, Mahadevan-Jansen A. Multi-modal nonlinear optical and thermal imaging platform for label-free characterization of biological tissue. Sci Rep 2021; 11:8067. [PMID: 33850171 PMCID: PMC8044215 DOI: 10.1038/s41598-021-86774-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Accepted: 03/08/2021] [Indexed: 11/09/2022] Open
Abstract
The ability to characterize the combined structural, functional, and thermal properties of biophysically dynamic samples is needed to address critical questions related to tissue structure, physiological dynamics, and disease progression. Towards this, we have developed an imaging platform that enables multiple nonlinear imaging modalities to be combined with thermal imaging on a common sample. Here we demonstrate label-free multimodal imaging of live cells, excised tissues, and live rodent brain models. While potential applications of this technology are wide-ranging, we expect it to be especially useful in addressing biomedical research questions aimed at the biomolecular and biophysical properties of tissue and their physiology.
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Affiliation(s)
- Wilson R Adams
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, 37235, USA
| | - Brian Mehl
- Thorlabs Imaging Research, Sterling, VA, USA
| | - Eric Lieser
- Thorlabs Imaging Research, Sterling, VA, USA
| | - Manqing Wang
- College of Bioengineering, Chongqing University, Chongqing, China
| | | | - Graham A Throckmorton
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, 37235, USA
| | - J Logan Jenkins
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, 37235, USA
| | - Jeremy B Ford
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, 37235, USA
| | - Rekha Gautam
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, 37235, USA
| | | | - E Duco Jansen
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, 37235, USA
- Department of Neurosurgery, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Anita Mahadevan-Jansen
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, 37235, USA.
- Department of Neurosurgery, Vanderbilt University Medical Center, Nashville, TN, 37232, USA.
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Sowers T, VanderLaan D, Karpiouk A, Donnelly EM, Smith E, Emelianov S. Laser threshold and cell damage mechanism for intravascular photoacoustic imaging. Lasers Surg Med 2019; 51:466-474. [PMID: 30302770 DOI: 10.1002/lsm.23026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/22/2018] [Indexed: 11/06/2022]
Abstract
OBJECTIVES Intravascular photoacoustic (IVPA) imaging is being developed to image atherosclerotic plaques, a leading cause of morbidity and mortality in the United States. However, the safety of this imaging modality, which requires repeated irradiation with short laser pulses, has not yet been investigated. This study has two objectives. First, determine in vitro the limit of cumulative fluence that can be applied to cells before death at IVPA relevant wavelengths. Second, evaluate if high single pulse fluences are a potential cause of cell death during IVPA imaging. MATERIALS AND METHODS Experiments were conducted using endothelial cells, macrophages, and smooth muscle cells. The cumulative fluence experiments were conducted at 1064 and 1197 nm, using a high pulse repetition frequency laser. Cells were irradiated with a wide range of cumulative fluences and evaluated for cell death. The thresholds for death were compared to the maximum expected clinical cumulative fluence. To evaluate the effect of single pulse fluences, cells were irradiated at 1064, 1210, and 1720 nm. Light was delivered at a range of pulse energies to emulate the fluences that cells would be exposed to during clinical IVPA imaging. RESULTS At 1064 nm, all three cell types remained viable at cumulative fluences above the maximum expected clinical cumulative fluence, which is calculated based on common IVPA imaging protocols. At 1197 nm, cells were viable near or just below the maximum expected clinical cumulative fluence, with some cell type to cell type variation. All three cell types remained viable after irradiation with high single pulse fluences at all three wavelengths. CONCLUSION The cumulative fluence experiments indicate that safety considerations are likely to put constraints on the amount of irradiation that can be used in IVPA imaging protocols. However, this study also indicates that it will be possible to use IVPA imaging safely, since cumulative fluences could be reduced by as much as two orders of magnitude below the maximum expected clinical cumulative fluence by varying the imaging protocol, albeit at the expense of image quality. The single pulse fluence experiments indicate that cell death from single pulse fluence is not likely during IVPA imaging. Thus, future studies should focus on heat accumulation as the likely mechanism of tissue damage. Lasers Surg. Med. 51:466-474, 2019. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Timothy Sowers
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia
| | - Don VanderLaan
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia
| | - Andrei Karpiouk
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia
| | - Eleanor M Donnelly
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, Atlanta, Georgia
| | - Ethan Smith
- Department of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia
| | - Stanislav Emelianov
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, Atlanta, Georgia
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8
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Miura Y, Seifert E, Rehra J, Kern K, Theisen-Kunde D, Denton M, Brinkmann R. Real-time optoacoustic temperature determination on cell cultures during heat exposure: a feasibility study. Int J Hyperthermia 2019; 36:466-472. [PMID: 30922131 DOI: 10.1080/02656736.2019.1590653] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
Objective/Purpose: In order to study the effects of hyperthermia and other temperature-related effects on cells and tissues, determining the precise time/temperature course is crucial. Here we present a non-contact optoacoustic technique, which provides temperatures during heating of cultured cells with scalable temporal and spatial resolution. METHODS A thulium laser (1.94 µm) with a maximum power of 15 W quickly and efficiently heats cells in a culture dish because of low penetration depth (1/e penetration depths of 78 µm) of the radiation in water. A repetitively Q-switched holmium laser (2.1 µm) is used simultaneously to probe temperatures at different locations in the dish by using the photoacoustic effect. Due to thermoelastic expansion of water, pressure waves are emitted and measured with an ultrasonic hydrophone at the side of the dish. The amplitudes of the waves are temperature dependent and can be used to calculate the temperature/time course at any location of probing. RESULTS We measured temperatures of up to 55 °C with a heating power of 6 W after 10 s, and subsequent lateral temperature profiles over time. Within this profile, temperature fluctuations were found, likely owing to thermal convection and water circulation. By using cultured retinal pigment epithelial cells, it is shown that the probe laser pulses alone cause no biological damage, while immediate cell damage occurs when heating for 10 s at temperatures exceeding 45 °C. CONCLUSIONS This method shows great potential not only as a noninvasive, non-contact method to determine temperature/time responses of cells in culture, but also for complex tissue and other materials.
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Affiliation(s)
- Yoko Miura
- a Medical Laser Center Lübeck , Lübeck , Germany.,b Institute of Biomedical Optics , University of Lübeck , Lübeck , Germany.,c Department of Ophthalmology , University Hospital Schleswig-Holstein , Campus Lübeck, Lübeck , Germany
| | - Eric Seifert
- a Medical Laser Center Lübeck , Lübeck , Germany
| | - Josua Rehra
- a Medical Laser Center Lübeck , Lübeck , Germany
| | | | | | - Michael Denton
- d 711th Human Performance Wing, Airman Systems Directorate, Bioeffects Division, Optic Radiation Bioeffects Branch , JBSA , Fort Sam Houston , TX , USA
| | - Ralf Brinkmann
- a Medical Laser Center Lübeck , Lübeck , Germany.,b Institute of Biomedical Optics , University of Lübeck , Lübeck , Germany
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LoBue SA, Tailor P, Gandhi JK, Loftness P, Olsen TW. A Model to Study Thermal Energy Delivery to the Choroid: A Comparison of Surgical Devices. Transl Vis Sci Technol 2019; 7:39. [PMID: 30619659 PMCID: PMC6314229 DOI: 10.1167/tvst.7.6.39] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 11/12/2018] [Indexed: 11/24/2022] Open
Abstract
Purpose We measure and compare surgical devices using an ex vivo, temperature-controlled, choroidal incision model during thermal energy transfer with a high-resolution infrared camera. Methods Ex vivo porcine choroidal tissue specimens (n = 516) were isolated and placed on a temperature-regulated (37°C) perfusion platform. We tested the pulsed electron avalanche knife (PEAK), micropulse laser (MpL), continuous laser (CL), and bipolar cautery (BpC) at three energy settings (11 [low], 45 [medium], and 134 [high] mJ/mm). Each device was clamped to a stationary mechanical arm. Movement of tissue specimens beneath the surgical device was achieved using a stepping motor-driven x-y table. An infrared video camera measured orthogonal temperature variation in the surrounding tissue. Results Increased power resulted in greater lateral thermal spread using all modalities (P < 0.001). Mean (standard deviation) lateral thermal spread at low energy was smallest for the MpL at 0.0 (0.01) mm (P < 0.001), whereas BpC had the least collateral tissue damage at medium and high energies (0.02 [0.08] and 0.34 [0.22] mm, respectively; P < 0.001). Fluidics of the ex vivo system may limit thermal spread. The PEAK had the greatest thermal spread across all energy groups (P < 0.001), with clinically relevant variation between disposable blades. Conclusions Our ex vivo model enabled direct comparison of threshold thermal tissue injury across four devices. MpL and BpC showed the least thermal damage. PEAK had a higher variation in energy delivery, but also has the advantage of more effective tissue cutting. Translational Relevance Our ex vivo surgical device analysis provides thermal tissue injury predictions for choroidal surgery.
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Affiliation(s)
- Stephen A LoBue
- Department of Ophthalmology, Mayo Clinic, Rochester, MN, USA.,Department of Ophthalmology, Emory University, Atlanta, GA, USA
| | | | - Jarel K Gandhi
- Department of Ophthalmology, Mayo Clinic, Rochester, MN, USA
| | | | - Timothy W Olsen
- Department of Ophthalmology, Mayo Clinic, Rochester, MN, USA.,Department of Ophthalmology, Emory University, Atlanta, GA, USA
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Kern K, Mertineit CL, Brinkmann R, Miura Y. Expression of heat shock protein 70 and cell death kinetics after different thermal impacts on cultured retinal pigment epithelial cells. Exp Eye Res 2018; 170:117-126. [PMID: 29454858 DOI: 10.1016/j.exer.2018.02.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 01/25/2018] [Accepted: 02/14/2018] [Indexed: 12/19/2022]
Abstract
Recent technologies are broadening the possibility to treat the retinal pigment epithelium (RPE) with different thermal impacts, from sublethal to lethal ranges. Thus temperature-dependent subcellular molecular responses need to be elucidated in more detail. In this study, RPE cell viability and expression of heat shock protein 70 (Hsp70) were investigated after thermal irradiation with different temperature increase using an in-vitro model. Primary porcine RPE cell cultures were irradiated with different laser power of a thulium laser (λ = 1940 nm, beam-diameter 30 mm) for 10 s, such that the maximal temperatures at the center of the culture dish (Tmax) reach 40, 44, 47, 51 or 59 °C after 10-s irradiation. The temperature distribution across the culture dish shows a Gaussian decay from central position to the periphery of the dish. At 3, 24 and 48 h after irradiation cell viability was assessed with fluorescence microscopy using cell viability-indicating fluorescence dyes, followed by the determination of the threshold temperature for apoptotic change and death of RPE cells. Intracellular localization and amount of Hsp70 were investigated with immunofluorescence and western blotting, respectively. The threshold temperature (at the 10th second of irradiation: T10s) for cellular apoptosis and complete cell death showed a decrease over time after irradiation, suggesting a long-term process of thermally induced cell death. For complete cell death the threshold T10s was 52.1 ± 0.6 °C, 50.1 ± 1.4 °C, and 50.1 ± 0.8 °C, for 3, 24 and 48 h, respectively, whereas for the apoptotic changes 48.6 ± 1.8 °C, 47.2 ± 1.3 °C, and 46.7 ± 0.9 °C, respectively. Quantitative analysis of Hsp70 with western blotting showed a significant increase in intracellular Hsp70 at lethal irradiation with Tmax ≥ 51 °C, up to 19.6 ± 2.3 fold after 48 h at 59 °C, whereas sub-lethal irradiations with Tmax ≤ 44 °C led to a slight tendency of time-dependent increases (up to 1.8 ± 1.1 fold) over 48 h. Immunostainings for Hsp70 showed a circle- or ring-pattern of the Hsp70 staining during 3-48 h after irradiation, and the range of the 1st and 3rd quartiles of T10s for heat-induced Hsp70 expression over this time period was between 44.8 °C and 48.2 °C. A very strong staining of Hsp70 was observed at the border to the damaged zone, where many cells show the strong staining in the whole cytoplasmic space, while some cells in the nucleus, or some cells show the signs of cell migration and proliferation. Moreover, among the cells showing high intensity of Hsp70 staining, there are small round cells like apoptotic cells. Results suggest that RPE cell death after thermal irradiation may take time, and mostly undergoes through apoptosis, unless cells are immediately killed. Thermal irradiation-induced Hsp70 expression is not only temperature-dependent, but also depends largely on the existence of neighboring cell death, suggesting the crucial role of Hsp70 in apoptosis and wound healing processes of RPE cells. The increase of Hsp70 over 24-48 h indicates its long-term roles in cell responses both after sublethal and lethal thermal laser irradiations.
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Affiliation(s)
- Katharina Kern
- Institute of Biomedical Optics, University of Lübeck, Lübeck, Germany; Medical Laser Center Lübeck, Lübeck, Germany
| | | | - Ralf Brinkmann
- Institute of Biomedical Optics, University of Lübeck, Lübeck, Germany; Medical Laser Center Lübeck, Lübeck, Germany
| | - Yoko Miura
- Institute of Biomedical Optics, University of Lübeck, Lübeck, Germany; Medical Laser Center Lübeck, Lübeck, Germany; Department of Ophthalmology, University of Lübeck, Lübeck, Germany.
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11
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Baade A, von der Burchard C, Lawin M, Koinzer S, Schmarbeck B, Schlott K, Miura Y, Roider J, Birngruber R, Brinkmann R. Power-controlled temperature guided retinal laser therapy. JOURNAL OF BIOMEDICAL OPTICS 2017; 22:1-11. [PMID: 29164836 DOI: 10.1117/1.jbo.22.11.118001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 10/25/2017] [Indexed: 06/07/2023]
Abstract
Laser photocoagulation has been a treatment method for retinal diseases for decades. Recently, studies have demonstrated therapeutic benefits for subvisible effects. A treatment mode based on an automatic feedback algorithm to reliably generate subvisible and visible irradiations within a constant irradiation time is introduced. The method uses a site-individual adaptation of the laser power by monitoring the retinal temperature rise during the treatment using optoacoustics. This provides feedback to adjust the therapy laser power during the irradiation. The technique was demonstrated on rabbits in vivo using a 532-nm continuous wave Nd:YAG laser. The temperature measurement was performed with 523-nm Q-switched Nd:YLF laser pulses with 75-ns pulse duration at 1-kHz repetition rate. The beam diameter on the fundus was 200 μm for both lasers, respectively. The aim temperatures ranged from 50°C to 75°C in 11 eyes of 7 rabbits. The results showed ophthalmoscopically invisible effects below 55°C with therapy laser powers over a wide range. The standard deviation for the measured temperatures ranged from 2.1°C for an aim temperature of 50°C to 4.7°C for 75°C. The ED50 temperature value for ophthalmoscopically visible lesions in rabbits was determined as 65.3°C. The introduced method can be used for retinal irradiations with adjustable temperature elevations.
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Affiliation(s)
| | - Claus von der Burchard
- University Medical Center of Schleswig-Holstein, Department of Ophthalmology, Kiel, Germany
| | - Meike Lawin
- Medizinisches Laserzentrum Lübeck GmbH, Lübeck, Germany
| | - Stefan Koinzer
- University Medical Center of Schleswig-Holstein, Department of Ophthalmology, Kiel, Germany
| | | | | | - Yoko Miura
- University of Lübeck, Institute of Biomedical Optics, Lübeck, Germany
| | - Johann Roider
- University Medical Center of Schleswig-Holstein, Department of Ophthalmology, Kiel, Germany
| | - Reginald Birngruber
- Medizinisches Laserzentrum Lübeck GmbH, Lübeck, Germany
- University of Lübeck, Institute of Biomedical Optics, Lübeck, Germany
| | - Ralf Brinkmann
- Medizinisches Laserzentrum Lübeck GmbH, Lübeck, Germany
- University of Lübeck, Institute of Biomedical Optics, Lübeck, Germany
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12
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Miura Y, Pruessner J, Mertineit CL, Kern K, Muenter M, Moltmann M, Danicke V, Brinkmann R. Continuous-wave Thulium Laser for Heating Cultured Cells to Investigate Cellular Thermal Effects. J Vis Exp 2017. [PMID: 28715366 DOI: 10.3791/54326] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
An original method to heat cultured cells using a 1.94 µm continuous-wave thulium laser for biological assessment is introduced here. Thulium laser radiation is strongly absorbed by water, and the cells at the bottom of the culture dish are heated through thermal diffusion. A laser fiber with a diameter of 365 µm is set about 12 cm above the culture dish, without any optics, such that the laser beam diameter is almost equivalent to the inner diameter of the culture dish (30 mm). By keeping a consistent amount of culture medium in each experiment, it is possible to irradiate the cells with a highly reproducible temperature increase. To calibrate the temperature increase and its distribution in one cell culture dish for each power setting, the temperature was measured during 10 s of irradiation at different positions and at the cellular level. The temperature distribution was represented using a mathematical graphics software program, and its pattern across the culture dish was in Gaussian form. After laser irradiation, different biological experiments could be performed to assess temperature-dependent cell responses. In this manuscript, viability staining (i.e., distinguishing live, apoptotic, and dead cells) is introduced to help determine the threshold temperatures for cell apoptosis and death after different points in time. The advantages of this method are the preciseness of the temperature and the time of heating, as well as its high efficiency in heating cells in a whole cell culture dish. Furthermore, it allows for study with a wide variety of temperatures and time durations, which can be well-controlled by a computerized operating system.
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Affiliation(s)
- Yoko Miura
- Institute of Biomedical Optics, University of Luebeck; Medical Laser Center Luebeck GmbH, University of Leubeck; Department of Ophthalmology, University of Luebeck;
| | | | | | | | | | | | - Veit Danicke
- Medical Laser Center Luebeck GmbH, University of Leubeck
| | - Ralf Brinkmann
- Institute of Biomedical Optics, University of Luebeck; Medical Laser Center Luebeck GmbH, University of Leubeck
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13
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Schlott K, Koinzer S, Baade A, Birngruber R, Roider J, Brinkmann R. Lesion strength control by automatic temperature guided retinal photocoagulation. JOURNAL OF BIOMEDICAL OPTICS 2016; 21:98001. [PMID: 27670670 DOI: 10.1117/1.jbo.21.9.098001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 08/26/2016] [Indexed: 06/06/2023]
Abstract
Laser photocoagulation is an established treatment for a variety of retinal diseases. However, when using the same irradiation parameter, the size and strength of the lesions are unpredictable due to unknown inter- and intraindividual optical properties of the fundus layers. The aim of this work is to investigate a feedback system to generate desired lesions of preselectable strengths by automatically controlling the irradiation time. Optoacoustics were used for retinal temperature monitoring. A 532-nm continuous wave Nd:YAG laser was used for photocoagulation. A 75-ns/523-nm Q-switched Nd:YLF laser simultaneously excited temperature-dependent pressure transients, which were detected at the cornea by an ultrasonic transducer embedded in a contact lens. The temperature data were analyzed during the irradiation by a LabVIEW routine. The treatment laser was switched off automatically when the required lesion strength was achieved. Five different feedback control algorithms for different lesion sizes were developed and tested on rabbits in vivo. With a laser spot diameter of 133???m, five different lesion types with ophthalmoscopically visible diameters ranging mostly between 100 and 200???m, and different appearances were achieved by automatic exposure time control. The automatically controlled lesions were widely independent of the treatment laser power and the retinal pigmentation.
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Affiliation(s)
- Kerstin Schlott
- University of Lübeck, Institute of Biomedical Optics, Peter-Monnik-Weg 4, 23562 Lübeck, Germany
| | - Stefan Koinzer
- University of Kiel, Department of Ophthalmology, Arnold-Heller-Straße 3, House 25, 24105 Kiel, Germany
| | - Alexander Baade
- Medical Laser Center Lübeck, Lübeck, Peter-Monnik-Weg 4, 23562 Lübeck, Germany
| | - Reginald Birngruber
- University of Lübeck, Institute of Biomedical Optics, Peter-Monnik-Weg 4, 23562 Lübeck, Germany
| | - Johann Roider
- University of Kiel, Department of Ophthalmology, Arnold-Heller-Straße 3, House 25, 24105 Kiel, Germany
| | - Ralf Brinkmann
- University of Lübeck, Institute of Biomedical Optics, Peter-Monnik-Weg 4, 23562 Lübeck, Germany
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14
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Koinzer S, Baade A, Schlott K, Hesse C, Caliebe A, Roider J, Brinkmann R. Temperature-Controlled Retinal Photocoagulation Reliably Generates Uniform Subvisible, Mild, or Moderate Lesions. Transl Vis Sci Technol 2015; 4:9. [PMID: 26473086 DOI: 10.1167/tvst.4.5.9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 07/21/2015] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Conventional retinal photocoagulation produces irregular lesions and does not allow reliable control of ophthalmoscopically invisible lesions. We applied automatically controlled retinal photocoagulation, which allows to apply uniform lesions without titration, and aimed at five different predictable lesion intensities in a study on rabbit eyes. METHODS A conventional 532-nm photocoagulation laser was used in combination with a pulsed probe laser. They facilitated real-time fundus temperature measurements and automatic exposure time control for different predefined time/temperature dependent characteristics (TTC). We applied 225 control lesions (exposure time 200 ms) and 794 TTC lesions (5 intensities, exposure times 7-800 ms) in six rabbit eyes with variable laser power (20-66.4 mW). Starting after 2 hours, we examined fundus color and optical coherence tomographic (OCT) images over 3 months and classified lesion morphologies according to a seven-stage OCT classifier. RESULTS Visibility rates in funduscopy (OCT) after 2 hours were 17% (68%) for TTC intensity group 1, 38% (90%) for TTC group 2 and greater than 94% (>98%) for all consecutive groups. TTC groups 1 through 4 correlated to increasing morphological lesion intensities and increasing median funduscopic and OCT diameters. Group 5 lesions were as large as, but more intense than group 4 lesions. CONCLUSIONS Automatic, temperature controlled photocoagulation allows to apply predictable subvisible, mild, or moderate lesions without manual power titration. TRANSLATIONAL RELEVANCE The technique will facilitate standardized, automatically controlled low and early treatment of diabetic retinopathy study (ETDRS) intensity photocoagulation independently of the treating physician, the treated eye and lesion location.
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Affiliation(s)
- Stefan Koinzer
- Department of Ophthalmology University hospital of Schleswig-Holstein, Kiel, Germany
| | | | | | - Carola Hesse
- Department of Ophthalmology University hospital of Schleswig-Holstein, Kiel, Germany
| | - Amke Caliebe
- Institute of Medical Informatics and Statistics, University hospital of Schleswig-Holstein, Kiel, Germany
| | - Johann Roider
- Department of Ophthalmology University hospital of Schleswig-Holstein, Kiel, Germany
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15
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Choi TY, Denton ML, Noojin GD, Estlack LE, Shrestha R, Rockwell BA, Thomas R, Kim D. Thermal evaluation of laser exposures in an in vitro retinal model by microthermal sensing. JOURNAL OF BIOMEDICAL OPTICS 2014; 19:97003. [PMID: 25222532 DOI: 10.1117/1.jbo.19.9.097003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 08/25/2014] [Indexed: 06/03/2023]
Abstract
A temperature detection system using a micropipette thermocouple sensor was developed for use within mammalian cells during laser exposure with an 8.6-μm beam at 532 nm. We have demonstrated the capability of measuring temperatures at a single-cell level in the microscale range by inserting micropipettebased thermal sensors of size ranging from 2 to 4 μm into the membrane of a live retinal pigment epithelium (RPE) cell subjected to a laser beam. We setup the treatment groups of 532-nm laser-irradiated single RPE cell and in situ temperature recordings were made over time. Thermal profiles are given for representative cells experiencing damage resulting from exposures of 0.2 to 2 s. The measured maximum temperature rise for each cell ranges from 39 to 73°C; the RPE cells showed a signature of death for all the cases reported herein. In order to check the cell viability, real-time fluorescence microscopy was used to identify the transition of pigmented RPE cells between viable and damaged states due to laser exposure.
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Affiliation(s)
- Tae Y Choi
- University of North Texas, Department of Mechanical and Energy Engineering, 3940 N. Elm Street Denton, Texas 76207, United States
| | - Michael L Denton
- TASC, Inc., Department of Biomedical Sciences and Technologies, 4141 Petroleum Road, JBSA Fort Sam Houston, Texas 78234, United States
| | - Gary D Noojin
- TASC, Inc., Department of Biomedical Sciences and Technologies, 4141 Petroleum Road, JBSA Fort Sam Houston, Texas 78234, United States
| | - Larry E Estlack
- Conceptual MindWorks, Inc., 4141 Petroleum Road, JBSA Fort Sam Houston, Texas 78234, United States
| | - Ramesh Shrestha
- University of North Texas, Department of Mechanical and Energy Engineering, 3940 N. Elm Street Denton, Texas 76207, United States
| | - Benjamin A Rockwell
- 711th Human Performance Wing, Bioeffects Division, Optical Radiation Bioeffects Branch, 4141 Petroleum Road, JBSA Fort Sam Houston, Texas 78234, United States
| | - Robert Thomas
- 711th Human Performance Wing, Bioeffects Division, Optical Radiation Bioeffects Branch, 4141 Petroleum Road, JBSA Fort Sam Houston, Texas 78234, United States
| | - Dongsik Kim
- POSTECH, Department of Mechanical Engineering, San 31 Hyoja-Dong, Nam-Gu, Pohang, Gyungbuk 790-784, Republic of Korea
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16
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Protective effect of a laser-induced sub-lethal temperature rise on RPE cells from oxidative stress. Exp Eye Res 2014; 124:37-47. [PMID: 24800654 DOI: 10.1016/j.exer.2014.04.014] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2014] [Revised: 03/22/2014] [Accepted: 04/18/2014] [Indexed: 11/22/2022]
Abstract
Recently introduced new technologies that enable temperature-controlled laser irradiation on the RPE allowed us to investigate temperature-resolved RPE cell responses. In this study we aimed primarily to establish an experimental setup that can realize laser irradiation on RPE cell culture with the similar temperature distribution as in the clinical application, with a precise time/temperature history. With this setup, we conducted investigations to elucidate the temperature-dependent RPE cell biochemical responses and the effect of transient hyperthermia on the responses of RPE cells to the secondary-exposed oxidative stress. Porcine RPE cells cultivated in a culture dish (inner diameter = 30 mm) with culture medium were used, on which laser radiation (λ = 1940 nm, spot diameter = 30 mm) over 10 s was applied as a heat source. The irradiation provides a radially decreasing temperature profile which is close to a Gaussian shape with the highest temperature in the center. Power setting for irradiation was determined such that the peak temperature (Tmax) in the center of the laser spot at the cells reaches from 40 °C to 58 °C (40, 43, 46, 50, 58 °C). Cell viability was investigated with ethidium homodimer III staining at the time points of 3 and 24 h following laser irradiation. Twenty four hours after laser irradiation the cells were exposed to hydrogen peroxide (H2O2) for 5 h, followed by the measurement of intracellular glutathione, intracellular 4-hydroxynonenal (HNE) protein adducts, and secreted vascular endothelial growth factor (VEGF). The mean temperature threshold for RPE cell death after 3 h was found to be around 52 °C, and for 24 h around 50 °C with the current irradiation setting. A sub-lethal preconditioning on Tmax = 43 °C significantly induced the reduced glutathione (GSH)/oxidized glutathione (GSSG) ratio, and decreased H2O2-induced increase of intracellular 4-HNE protein adducts. Although sub-lethal hyperthermia (Tmax = 40 °C, 43 °C, and 46 °C) caused a slight increase of VEGF secretion in 6 h directly following irradiation, secondary exposed H2O2-induced VEGF secretion was significantly reduced in the sub-lethally preheated groups, where the largest effect was seen following the irradiation with Tmax = 43 °C. In summary, the current results suggest that sub-lethal thermal laser irradiation on the RPE at Tmax = 43 °C for 10 s enhances cell defense system against oxidative stress, with increasing the GSH/GSSG ratio. Together with the results that the decreased amount of H2O2-induced 4-HNE in sub-lethally preheated RPE cells was accompanied by the lower secretion of VEGF, it is also strongly suggested that the sub-lethal hyperthermia may modify RPE cell functionality to protect RPE cells from oxidative stress and associated functional decrease, which are considered to play a significant role in the pathogenesis of age-related macular degeneration and other chorioretinal degenerative diseases.
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17
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Ahmed EM, Barrera FJ, Early EA, Denton ML, Clark CD, Sardar DK. Maxwell's equations-based dynamic laser-tissue interaction model. Comput Biol Med 2013; 43:2278-86. [PMID: 24290944 DOI: 10.1016/j.compbiomed.2013.09.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Revised: 09/05/2013] [Accepted: 09/07/2013] [Indexed: 11/29/2022]
Abstract
Since its invention in the early 1960s, the laser has been used as a tool for surgical, therapeutic, and diagnostic purposes. To achieve maximum effectiveness with the greatest margin of safety it is important to understand the mechanisms of light propagation through tissue and how that light affects living cells. Lasers with novel output characteristics for medical and military applications are too often implemented prior to proper evaluation with respect to tissue optical properties and human safety. Therefore, advances in computational models that describe light propagation and the cellular responses to laser exposure, without the use of animal models, are of considerable interest. Here, a physics-based laser-tissue interaction model was developed to predict the dynamic changes in the spatial and temporal temperature rise during laser exposure to biological tissues. Unlike conventional models, the new approach is grounded on the rigorous electromagnetic theory that accounts for wave interference, polarization, and nonlinearity in propagation using a Maxwell's equations-based technique.
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Affiliation(s)
- Elharith M Ahmed
- Department of Physics and Astronomy, University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249, USA; TASC Inc., 4141 Petroleum Road, Ft. Sam Houston, TX 78234-2644, USA
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18
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Koinzer S, Hesse C, Caliebe A, Saeger M, Baade A, Schlott K, Brinkmann R, Roider J. Photocoagulation in rabbits: Optical coherence tomographic lesion classification, wound healing reaction, and retinal temperatures. Lasers Surg Med 2013; 45:427-36. [DOI: 10.1002/lsm.22163] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/13/2013] [Indexed: 11/12/2022]
Affiliation(s)
- Stefan Koinzer
- Department of Ophthalmology; University Hospital of Schleswig-Holstein; Campus Kiel; House 25 Arnold-Heller-Str. 3 24105 Kiel Germany
| | - Carola Hesse
- Department of Ophthalmology; University Hospital of Schleswig-Holstein; Campus Kiel; House 25 Arnold-Heller-Str. 3 24105 Kiel Germany
| | - Amke Caliebe
- Institute of Medical Informatics and Statistics; University Hospital of Schleswig-Holstein; Campus Kiel; House 31 Arnold-Heller-Str. 3 24105 Kiel Germany
| | - Mark Saeger
- Department of Ophthalmology; University Hospital of Schleswig-Holstein; Campus Kiel; House 25 Arnold-Heller-Str. 3 24105 Kiel Germany
| | - Alexander Baade
- Medical Laser Center Lübeck GmbH; Peter-Monnik-Weg 4 23562 Lübeck Germany
| | - Kerstin Schlott
- Medical Laser Center Lübeck GmbH; Peter-Monnik-Weg 4 23562 Lübeck Germany
| | - Ralf Brinkmann
- Medical Laser Center Lübeck GmbH; Peter-Monnik-Weg 4 23562 Lübeck Germany
| | - Johann Roider
- Department of Ophthalmology; University Hospital of Schleswig-Holstein; Campus Kiel; House 25 Arnold-Heller-Str. 3 24105 Kiel Germany
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19
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Koinzer S, Schlott K, Portz L, Ptaszynski L, Baade A, Bever M, Saeger M, Caliebe A, Denner R, Birngruber R, Brinkmann R, Roider J. Correlation of temperature rise and optical coherence tomography characteristics in patient retinal photocoagulation. JOURNAL OF BIOPHOTONICS 2012; 5:889-902. [PMID: 22899667 DOI: 10.1002/jbio.201200091] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Revised: 07/03/2012] [Accepted: 07/08/2012] [Indexed: 06/01/2023]
Abstract
We conducted a study to correlate the retinal temperature rise during photocoagulation to the afterward detected tissue effect in optical coherence tomography (OCT). 504 photocoagulation lesions were examined in 20 patients. The retinal temperature increase was determined in real-time during treatment based on thermoelastic tissue expansion which was probed by repetitively applied ns laser pulses. The tissue effect was examined on fundus images and OCT images of individualized lesions. We discerned seven characteristic morphological OCT lesion classes. Their validity was confirmed by increasing visibility and diameters. Mean peak temperatures at the end of irradiation ranged from approx. 60 °C to beyond 100 °C, depending on burn intensity.
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Affiliation(s)
- Stefan Koinzer
- Department of Ophthalmology, University of Kiel, Kiel, Germany.
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20
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Schlott K, Koinzer S, Ptaszynski L, Bever M, Baade A, Roider J, Birngruber R, Brinkmann R. Automatic temperature controlled retinal photocoagulation. JOURNAL OF BIOMEDICAL OPTICS 2012; 17:061223. [PMID: 22734753 DOI: 10.1117/1.jbo.17.6.061223] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Laser coagulation is a treatment method for many retinal diseases. Due to variations in fundus pigmentation and light scattering inside the eye globe, different lesion strengths are often achieved. The aim of this work is to realize an automatic feedback algorithm to generate desired lesion strengths by controlling the retinal temperature increase with the irradiation time. Optoacoustics afford non-invasive retinal temperature monitoring during laser treatment. A 75 ns/523 nm Q-switched Nd:YLF laser was used to excite the temperature-dependent pressure amplitudes, which were detected at the cornea by an ultrasonic transducer embedded in a contact lens. A 532 nm continuous wave Nd:YAG laser served for photocoagulation. The ED50 temperatures, for which the probability of ophthalmoscopically visible lesions after one hour in vivo in rabbits was 50%, varied from 63°C for 20 ms to 49°C for 400 ms. Arrhenius parameters were extracted as ΔE=273 J mol(-1) and A=3 x 10(44) s(-1). Control algorithms for mild and strong lesions were developed, which led to average lesion diameters of 162 ± 34 μm and 189 ± 34 μm, respectively. It could be demonstrated that the sizes of the automatically controlled lesions were widely independent of the treatment laser power and the retinal pigmentation.
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Affiliation(s)
- Kerstin Schlott
- University of Lübeck, Institute of Biomedical Optics, Peter-Monnik-Weg 4, D-23562, Lübeck, Germany.
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21
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Brinkmann R, Koinzer S, Schlott K, Ptaszynski L, Bever M, Baade A, Luft S, Miura Y, Roider J, Birngruber R. Real-time temperature determination during retinal photocoagulation on patients. JOURNAL OF BIOMEDICAL OPTICS 2012; 17:061219. [PMID: 22734749 DOI: 10.1117/1.jbo.17.6.061219] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The induced thermal damage in retinal photocoagulation depends on the temperature increase and the time of irradiation. The temperature rise is unknown due to intraocular variations in light transmission, scattering and grade of absorption in the retinal pigment epithelium (RPE) and the choroid. Thus, in clinical practice, often stronger and deeper coagulations are applied than therapeutically needed, which can lead to extended neuroretinal damage and strong pain perception. This work focuses on an optoacoustic (OA) method to determine the temperature rise in real-time during photocoagulation by repetitively exciting thermoelastic pressure transients with nanosecond probe laser pulses, which are simultaneously applied to the treatment radiation. The temperature-dependent pressure amplitudes are non-invasively detected at the cornea with an ultrasonic transducer embedded in the contact lens. During clinical treatment, temperature courses as predicted by heat diffusion theory are observed in most cases. For laser spot diameters of 100 and 300 μm, and irradiation times of 100 and 200 ms, respectively, peak temperatures range between 70°C and 85°C for mild coagulations. The obtained data look very promising for the realization of a feedback-controlled treatment, which automatically generates preselected and reproducible coagulation strengths, unburdens the ophthalmologist from manual laser dosage, and minimizes adverse effects and pain for the patient.
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Affiliation(s)
- Ralf Brinkmann
- University of Lübeck, Institute of Biomedical Optics, Lübeck, Germany.
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Saha A, Arora R, Yakovlev VV, Burke JM. Raman microspectroscopy of melanosomes: the effect of long term light irradiation. JOURNAL OF BIOPHOTONICS 2011; 4:805-813. [PMID: 21800432 DOI: 10.1002/jbio.201100008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Revised: 06/16/2011] [Accepted: 06/17/2011] [Indexed: 05/31/2023]
Abstract
Melanosomes are long lived organelles in retinal pigment epithelium cells and are primarily responsible for photoprotection. However, with aging or prolong light radiation, the function of melanosomes diminishes, which may be due to photobleaching of melanin pigments present in melanosomes. In this study, melanosomes were isolated from the retinal pigment epithelium cells and exposed to green light (532 nm), and the chemical changes were monitored using Raman microspectroscopy. Photochemical changes were recorded for different power levels and exposure times. The threshold power and the rate for irreversible photobleaching of melanosomes were calculated by fitting the experimental data with a proposed model.
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Affiliation(s)
- Anushree Saha
- School of Medicine, Case Western Reserve University, 2085 Adelbert Road, OH 44106, USA.
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