Selective RPE photodestruction: mechanism of cell damage by pulsed-laser irradiance in the ns to μm time regime

Brinkmann, Ralf; Roegener, Jan; Lin, Charles P.; Roider, Johann; Birngruber, Reginald; Huettmann, Gereon

doi:10.1117/12.350041

Cited by 10 publications

(24 citation statements)

References 11 publications

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“…Consequently the thresholds for cell death (412 mJ/cm ) and for bubble detection (456 mJ/cm^) are both higher than for 12 nsec pulses. However, this increase in threshold is not as dramatic as the values predicted for bubble formation around a single, isolated melanosome [4]. Mutual heating among the closely-spaced melanosome particles within the RPE cell can be a significant cause for the temperature increase during the microsecond laser pulses, leading to higher temperatures than an isolated melanosome would reach [4].…”

Section: Significancementioning

confidence: 86%

“…However, this increase in threshold is not as dramatic as the values predicted for bubble formation around a single, isolated melanosome [4]. Mutual heating among the closely-spaced melanosome particles within the RPE cell can be a significant cause for the temperature increase during the microsecond laser pulses, leading to higher temperatures than an isolated melanosome would reach [4]. Mutual heating is insignificant for 12 nsec pulses because there is much less heat diffiision outside the particles.…”

Section: Significancementioning

confidence: 88%

“…These pigment microparticles form intracellular hot spots and initiate microscopic cavitation bubbles that expand and collapse on the timescale of 0.1 -1 ^sec [1][2][3]. The mechanical actions associated with microbubble expansion and implosion imparts damage to cells [2][3][4][5].…”

Section: Collaborators/consultantsmentioning

confidence: 99%

“…This was done to ensure that the measurement condition was the same as that used in previous stroboscopic imaging experiments. Since the temperature required for bubble formation at the surface of the melanosom has been determined to be about 150°C [4], a background temperature of 20 or 35°C was not expected to make a significant difference in the threshold. On the other hand, for 6 |is pulses the sample was kept at a more physiologic temperature of 35°C in order not to bias our measurement against a potential thermal contribution to the cell death mechanism.…”

Section: Collaborators/consultantsmentioning

confidence: 99%

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Mechanism of Ultrashort Pulse Laser Injury to the RPE (Retinal Pigment Epithelium)

Lin¹

2003

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Section: Significancementioning

confidence: 86%

Section: Significancementioning

confidence: 88%

Section: Collaborators/consultantsmentioning

confidence: 99%

Section: Collaborators/consultantsmentioning

confidence: 99%

See 2 more Smart Citations

Mechanism of Ultrashort Pulse Laser Injury to the RPE (Retinal Pigment Epithelium)

Lin¹

2003

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“…15 We have demonstrated using a slit lamp adapted laser scanner that SRT can also be achieved in vivo in rabbits by scanning the spot ͑diameter of about one RPE cell͒ of a cw laser across the retina so as to produce microsecond-short exposure at each targeted RPE cell. 16,17 However, accurate dosimetry in a clinical setting will be complicated partly because the absorption coefficient of ocular melanosomes is not well described; available values in the literature [18][19][20][21][22] vary from about 0.2 m −1 to 1.3 m −1 . Furthermore, the number of absorbing melanosomes per RPE cell differs among individuals and is not necessarily uniformly distributed within an individual eye.…”

Section: Introductionmentioning

confidence: 99%

Optical detection of intracellular cavitation during selective laser targeting of the retinal pigment epithelium: dependence of cell death mechanism on pulse duration

et al. 2007

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Selective laser targeting of the retinal pigment epithelium (RPE) is an attractive method for treating RPE-associated disorders. We are developing a method for optically detecting intracellular microcavitation that can potentially serve as an immediate feedback of the treatment outcome. Thermal denaturation or intracellular cavitation can kill RPE cells during selective targeting. We examined the cell damage mechanism for laser pulse durations from 1 to 40 micros ex vivo. Intracellular cavitation was detected as a transient increase in the backscattered treatment beam. Cavitation and cell death were correlated for individual cells after single-pulse irradiation. The threshold radiant exposures for cell death (ED(50,d)) and cavitation (ED(50,c)) increased with pulse duration and were approximately equal for pulses of up to 10 micros. For 20 micros, the ED(50,d) was about 10% lower than the ED(50,c); the difference increased with 40-micros pulses. Cells were killed predominantly by cavitation (up to 10-micros pulses); probability of thermally induced cell death without cavitation gradually increases with pulse duration. Threshold measurements are discussed by modeling the temperature distribution around laser-heated melanosomes and the scattering function from the resulting cavitation. Detection of intracellular cavitation is a highly sensitive method that can potentially provide real-time assessment of RPE damage during selective laser targeting.

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Nanoparticles for Cancer Treatment

Avedisian

Cavicchi

McEuen

et al. 2009

Annals of the New York Academy of Sciences

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An overview is presented of an approach for treating cancer that uses nanoparticles to deliver heat to diseased areas after absorbing energy from a laser of the appropriate wavelength. The implications are discussed of the relationship of parameters necessary to raise the temperature to therapeutically beneficial levels. Tight focusing is required for a continuous-wave laser to sufficiently heat individual nanoparticles because of heat loss to the surrounding fluid during the period of exposure. The natural thermal confinement of pulse lasers minimizes this effect because of the finite thermal diffusion time, which restricts the absorbed energy to a region around the particle, that offers the potential for achieving high temperatures that can promote phase change on the surface of a nanoparticle or even melting of the particle. A discussion of a way to potentially measure temperature on the scale of an individual nanoparticle is included based on using a single-walled nanotube (SWNT) of carbon as a thermistor. The challenges of this undertaking are that SWNTs do not always follow Ohm's law, they may exhibit metallic or semiconductor behavior with an often unpredictable result in manufacturing, and no two SWNTs behave identically, which necessitates calibration for each SWNT. Some results are presented that show the electrical characteristics of SWNTs and their potential for exploitation in this application.

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Selective RPE photodestruction: mechanism of cell damage by pulsed-laser irradiance in the ns to μm time regime

Cited by 10 publications

References 11 publications

Mechanism of Ultrashort Pulse Laser Injury to the RPE (Retinal Pigment Epithelium)

Mechanism of Ultrashort Pulse Laser Injury to the RPE (Retinal Pigment Epithelium)

Optical detection of intracellular cavitation during selective laser targeting of the retinal pigment epithelium: dependence of cell death mechanism on pulse duration

Nanoparticles for Cancer Treatment

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