Accession Number:

ADA523201

Title:

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

Descriptive Note:

Journal article

Corporate Author:

NORTHROP GRUMMAN CORP SAN ANTONIO TX INFORMATION TECHNOLOGY

Report Date:

2010-05-07

Pagination or Media Count:

4.0

Abstract:

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.

Subject Categories:

  • Anatomy and Physiology
  • Radiation and Nuclear Chemistry
  • Lasers and Masers

Distribution Statement:

APPROVED FOR PUBLIC RELEASE