Research Papers

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

[+] Author Affiliations
Ho Lee

Wellman Center for Photomedicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114 and KyungPook National University, School of Mechanical Engineering, Daegu, 701-702, Korea

Clemens Alt

Wellman Center for Photomedicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114 and Tufts University, Department of Biomedical Engineering, Medford, Massachusetts 02114

Costas M. Pitsillides

Wellman Center for Photomedicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114 and Boston University, Department of Biomedical Engineering, Boston, Massachusetts 02114

Charles P. Lin

Wellman Center for Photomedicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114

J. Biomed. Opt. 12(6), 064034 (November 12, 2007). doi:10.1117/1.2804078
History: Received July 25, 2006; Revised June 11, 2007; Accepted June 12, 2007; Published November 12, 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 40μsex 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 (ED50,d) and cavitation (ED50,c) increased with pulse duration and were approximately equal for pulses of up to 10μs. For 20μs, the ED50,d was about 10% lower than the ED50,c; the difference increased with 40-μs pulses. Cells were killed predominantly by cavitation (up to 10-μs 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.

© 2007 Society of Photo-Optical Instrumentation Engineers

Citation

Ho Lee ; Clemens Alt ; Costas M. Pitsillides and Charles P. Lin
"Optical detection of intracellular cavitation during selective laser targeting of the retinal pigment epithelium: dependence of cell death mechanism on pulse duration", J. Biomed. Opt. 12(6), 064034 (November 12, 2007). ; http://dx.doi.org/10.1117/1.2804078


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