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Proceedings Paper

In-vivo and in-vitro selective targeting of the retinal pigment epithelium using a laser-scanning device
Author(s): Clemens Alt; Carsten Framme; Susanne Schnell; Georg Schuele; Ralf Brinkmann; Charles P. Lin
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Paper Abstract

Laser photocoagulation is a well-established treatment modality for a variety of retinal disorders, but is difficult to use near the fovea due to thermal retinal destruction. Certain diseases, such as drusen maculopathy, are thought to be caused by a dysfunction of the Retinal Pigment Epithelium. For those diseases selective targeting of the RPE, sparing the adjoining photoreceptors, might be the appropriate treatment to avoid laser scotoma, as it has been shown with application of a train of ms laser pulses by Birngruber and Roider. Our new approach is to use a conventional green cw laser and rapidly scan a small laser spot over the retina so as to produce microsecond(s) -illumination at each RPE cell. Two scanning devices were developed using acousto-optic deflectors. For the in vitro experiments the ED50 value RPE cell damage was 170 mW with 100 exposures, scanning with a speed of 1 spot diameter/3 microsecond(s) . In vivo experiments demonstrated an angiographic ED50 threshold of 66 mW for 100 exposures while scanning with an effective illumination time of 5 microsecond(s) . The ophthalmoscopic threshold was higher than a factor of 2 times the angiographic ED50. Using separated scan lines we show selectivity in the form of surviving cells in between irradiated lines. Selective destruction of RPE cells is possible using laser-scanning devices.

Paper Details

Date Published: 13 June 2002
PDF: 5 pages
Proc. SPIE 4611, Ophthalmic Technologies XII, (13 June 2002); doi: 10.1117/12.470607
Show Author Affiliations
Clemens Alt, Harvard Medical School (United States)
Carsten Framme, Harvard Medical School and Medical Laser Ctr. Luebeck and Univ. of Regensburg (Germany)
Susanne Schnell, Harvard Medical School (United States)
Georg Schuele, Medical Laser Ctr. Luebeck (Germany)
Ralf Brinkmann, Medical Laser Ctr. Luebeck (Germany)
Charles P. Lin, Harvard Medical School (United States)

Published in SPIE Proceedings Vol. 4611:
Ophthalmic Technologies XII
Fabrice Manns; Per G. Soederberg; Arthur Ho, Editor(s)

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