In-vitro Retinal Model Reveals a Sharp Transition between Laser Damage Mechanisms

We determined laser damage thresholds at 413 nm using a novel environmentally controlled enclosure and a previously described artificially pigmented RPE cell model. Exposure duration ranged from 0.1 to 200 s for a 0.3-mm beam, and 100 to 200 s for a 2.5-mm beam. We found substantial differences betw...

Full description

Saved in:
Bibliographic Details
Main Authors: Denton, Michael L, Clark, III, C D, Foltz, Michael S, Schuster, Kurt J, Noojin, Gary D, Estlack, Larry E, Thomas, Robert J
Format: Report
Language:English
Subjects:
Anatomy and Physiology
CELLS
IN VITRO ANALYSIS
LASER DAMAGE
LASER-INDUCED DAMAGE
Lasers and Masers
NONTHERMAL EFFECTS
PE61102F
PHOTOCHEMICAL
PHOTOCHEMICAL REACTIONS
PHOTOTHERMAL
PHOTOTHERMAL PROPERTIES
Radiation and Nuclear Chemistry
REPRINTS
RETINA
RPE(RETINAL PIGMENT EPITHELIAL)
THERMAL EFFECTS
THERMAL MODE
THERMAL PROPERTIES
TRANSITIONS
WUAFRL2312AH02
Online Access:Request full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:We determined laser damage thresholds at 413 nm using a novel environmentally controlled enclosure and a previously described artificially pigmented RPE cell model. Exposure duration ranged from 0.1 to 200 s for a 0.3-mm beam, and 100 to 200 s for a 2.5-mm beam. We found substantial differences between the thresholds for the two beam sizes, which we attribute to a continuing thermal contribution with the larger beam. To better understand the transition from photothermal to photochemical mechanisms, damage from the 0.3-mm beam was assessed with greater temporal resolution between 20 to 100 s. The thresholds for all exposures between 0.1 and 60 s followed the same power function, indicating the same damage rate regardless of mechanism. However, the transition to pure photochemical damage (irradiance reciprocity) was characterized by a sudden 2-fold reduction in threshold value between the exposure durations of 60 and 100 s. Predicted temperature rise data from our thermal model support the theory of a significant thermal component in the damage generated by 60-s exposure. The thermal simulations also support the notion that laser beam diameter, in addition to wavelength and exposure duration, can influence when cells are damaged by purely photochemical means. Published in the Journal of Biomedical Optics, v15 n3 p030512-1 through 030512-3, May/Jun 2010. Prepared in cooperation with TASC, Inc., Brooks City-Base, TX; Conceptual MindWorks, Inc., San Antonio, TX; and Air Force Research Laboratory (AFRL), Brooks City-Base, TX. Sponsored in part by Air Force Office of Scientific Research (AFOSR), grant no. 92HE04COR. The original document contains color images.