Selective damage of pigmented cells by means of a rapidly scanned cw laser beam

Ralf Brinkmann*, Norbert Koop, Mustafa Özdemir, Clemens Alt, Georg Schüle, Charles P. Lin, Reginald Birngruber

*Corresponding author for this work


Selective targeting the retinal pigment epithelium (RPE) while sparing adjacent tissue such as the photoreceptors has been demonstrated by repetitively irradiating the fundus with a train of green μs-laser pulses. The aim of this study was to investigate selective RPE effects alternatively by means of rapidly scanning a cw-laser beam across the RPE to obtain the required μ s-illumination times. The radiation of an Ar+ laser (514 nm) was transmitted through a 25 μm core diameter fiber to a scanner unit. The fiber tip was imaged onto the object plane with a magnification of 0.75. The beam was repetitively scanned across porcine RPE samples in vitro providing an irradiation time of 1.6 μ s. Cell damage was investigated with a fluorescence viability assay. The ED50 cell damage power was determined to 580 mW when applying 10 exposures with a repetition rate of 500 Hz. It decreases to 250 mW for 500 exposures and more. The threshold keeps constant for an axial focus displacement of about 250 μ m. In conclusion, selective cell targeting has been proved with a laser scanning device. The technique can be adapted for clinical RPE treatment to a slit-lamp or by modifying a retina angiograph.

Original languageEnglish
Title of host publicationLaser Tissue Interaction XIII: Photochemical, Photothermal, and Photomechanical
EditorsSteven L. Jacques, Donald Dean Duncan, Sean J. Kirkpatrick, Andres Kriete , Donald Dean Duncan, Sean J. Kirkpatrick, Andres Kriete
Number of pages7
Publication date27.06.2002
Publication statusPublished - 27.06.2002
EventLaser Tissue Interaction XIII: Photochemical, Photothermal and Photomechanical - San Jose, United States
Duration: 20.01.200223.01.2002
Conference number: 59829

Research Areas and Centers

  • Academic Focus: Biomedical Engineering


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