Evaluation of retinal exposures from repetitively pulsed and scanning lasers.

Published

Journal Article

Threshold damage in the macaque retina is shown to be equivalent for the argon-krypton (Ar-Kr) 647 nm and the helium-neon (He-Ne) 632.8-nm lines for exposures to continuous wave (CW) radiation from 1 to 1,000 s. This equivalence allows interpolation from experiments with 647-nm, exposures at power levels that are unavailable with the He-Ne laser. To simulate He-Ne laser scanner exposures, 40-microseconds pulses of 647-nm light transmitted through a revolving disk with holes in the periphery were used to expose the retinas of monkeys under deep anesthesia at pulse repetition frequencies (PRFs) of 100, 200, 400, and 1,600 Hz for exposure durations of 1, 10, 100, and 1,000 s. The thresholds between laser exposure at 488 nm (Ar-Kr) and between laser exposure at 647 nm (Kr) are compared to assess thermal versus photochemical effects on the retina. The threshold for 488-nm pulses was consistently lower than that for 647-nm pulses at all PRFs and exposure times. The difference in thresholds increased with exposure time and PRF. The sharp decreases in 488-nm thresholds at 100-s exposure times for each PRF can be interpreted as a basically photochemical effect. The radiant exposure required for damage at 647 nm was several orders of magnitude above the radiant exposure from typical He-Ne scanner applications. From the similarity of the macaque retina to the human retina, it is concluded that no realistic ocular hazard exists from exposure to scanning laser systems of 1 mW or less, operating at higher than 100 Hz.

Full Text

Cited Authors

  • Ham, WT; Mueller, HA; Wolbarsht, ML; Sliney, DH

Published Date

  • March 1988

Published In

Volume / Issue

  • 54 / 3

Start / End Page

  • 337 - 344

PubMed ID

  • 3346165

Pubmed Central ID

  • 3346165

Electronic International Standard Serial Number (EISSN)

  • 1538-5159

International Standard Serial Number (ISSN)

  • 0017-9078

Digital Object Identifier (DOI)

  • 10.1097/00004032-198803000-00011

Language

  • eng