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

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

doi:10.1117/12.350041

14 June 1999 Selective RPE photodestruction: mechanism of cell damage by pulsed-laser irradiance in the ns to μm time regime

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

Author Affiliations +

Proceedings Volume 3601, Laser-Tissue Interaction X: Photochemical, Photothermal, and Photomechanical; (1999) https://doi.org/10.1117/12.350041
Event: BiOS '99 International Biomedical Optics Symposium, 1999, San Jose, CA, United States

Abstract

The subject of this study was to investigate the threshold radiant exposures for bubble formation at single porcine melanosomes in suspension and for porcine RPE cell damage when using pulse durations in the ns to microsecond(s) time regime. A frequency doubled Nd:YLF laser ((lambda) equals 527 nm) with adjustable pulse duration between 250 ns and 3 microsecond(s) and a Q- switched Nd:YAG laser ((lambda) equals 532 nm, (tau) equals 8 ns) were used for the single pulse irradiation. Fast flash photography was applied to probe vaporization around individual melanosomes while a fluorescence viability assay was used to probe cell vitality. Applying single ns laser pulses to RPE cells, an ED₅₀ threshold radiant exposure of 84 mJ/cm² was determined, which is close to the vaporization threshold around single melanosomes. When irradiating with pulse durations of 3 microsecond(s) , a threshold of about 223 mJ/cm² was measured, which is only 40% lower of the vaporization threshold around the single melanosome at that pulse width. This can be explained with heat contribution from adjacent melanosomes, which increases towards longer pulse durations. Calculations are in good agreement with the experimental results when assuming a surface temperature at the melanosome of 140 degrees Celsius and an absorption coefficient of 8000 cm^-1 to initiate vaporization. It can be concluded that the origin of RPE cell damage for single pulse irradiation with a duration of 8 ns results from transient microbubbles around the melanosomes, which lead to a transiently increased cell volume and subsequently a rupture of the cell structure. It is also likely that the same effect plays the major role when using pulse durations up to 3 microsecond(s) .

Citation Download Citation

Ralf Brinkmann, Jan Roegener, Charles P. Lin, Johann Roider M.D., Reginald Birngruber, and Gereon Huettmann "Selective RPE photodestruction: mechanism of cell damage by pulsed-laser irradiance in the ns to μm time regime", Proc. SPIE 3601, Laser-Tissue Interaction X: Photochemical, Photothermal, and Photomechanical, (14 June 1999); https://doi.org/10.1117/12.350041

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available