April 2010
Volume 51, Issue 13
Free
ARVO Annual Meeting Abstract  |   April 2010
Competing Photochemical Retinal Damage Mechanisms From Visible Light: Implications for Human Retinal Exposure Limits
Author Affiliations & Notes
  • D. H. Sliney
    Army Medical Dept (retired), Consulting Medical Physicist, Fallston, Maryland
  • J. J. Hunter
    Center for Visual Science, University of Rochester, Rochester, New York
  • F. C. Delori
    Schepens Eye Research Institute, Harvard Medical School, Boston, Massachusetts
  • D. R. Williams
    Center for Visual Science, University of Rochester, Rochester, New York
  • J. Mellerio
    University of Westminster, London, United Kingdom
  • Footnotes
    Commercial Relationships  D.H. Sliney, None; J.J. Hunter, Polgenix, Inc., F; F.C. Delori, None; D.R. Williams, Polgenix, Inc., F; Optos, C; U.S. Patents #5,777,719, #5,949,521, #6,095,651, #6,379,005, #6,948,818, #6,199,986, #6,299,311, #6,827,444, #6,264,328, #6,338,559, #20080007693, P; J. Mellerio, None.
  • Footnotes
    Support  NIH Grants EY004367, EY001319, EY014375; Research to Prevent Blindness; This work made use of STC shared experimental facilities supported by the NSF under Agreement No. AST-9876783
Investigative Ophthalmology & Visual Science April 2010, Vol.51, 3456. doi:https://doi.org/
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      D. H. Sliney, J. J. Hunter, F. C. Delori, D. R. Williams, J. Mellerio; Competing Photochemical Retinal Damage Mechanisms From Visible Light: Implications for Human Retinal Exposure Limits. Invest. Ophthalmol. Vis. Sci. 2010;51(13):3456. doi: https://doi.org/.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose: : To evaluate if recently published retinal injury thresholds (Morgan et al., 2008) make it necessary to revise current light safety guidelines for human retinal exposure to protect against photochemical injury.

Methods: : We reviewed known retinal injury thresholds from studies of mammalian retinae that provided reliable dosimetric information. Of particular value were those that attempted to determine action spectra or explored the potential photochemical damage mechanism. Threshold data from thermal injury were excluded.

Results: : Traditionally, the guidelines for limiting human exposure to bright light have been the retinal-thermal limits (400-1400 nm) and the blue light hazard (BLH) limits (380-550 nm). The BLH has a well-defined action spectrum peaking near 445 nm for the normal phakic eye. Two types of photochemically induced retinal injury have been well reported: Type 1 and Type 2. Type 1 is typically seen in animals exposed for many hours to fluorescent lamps (LV ~ 1 cd•cm-2, retinal irradiance approx 0.1 mW•cm-2). Since the action spectrum indicates that injury results from saturation of the visual pigment regeneration cycle (i.e., from a full bleach), exposure limits were not needed. Type 2 results from focal exposures to short-wavelengths for fractions of an hour, but the chromophore is still debated. The luminous efficacy of radiation at 568 nm is 654 lm/W, near the max of 683 lm/W, which suggests the damage mechanism could be due to saturation of cone-opsin regeneration in the RPE. Retinal changes reported by Morgan et al (2008) at 568 nm were similar to those found in full-bleach, flash-blindness studies (retinal illuminance > 7 logTd-sec).

Conclusions: : Although previously developed retinal exposure limits are still relevant for the awake, task-oriented eye, this is not the case for ophthalmic instrument exposure--particularly to the anesthetized eye during surgery. Until the action spectrum for this kind of damage is determined, we propose that the retinal radiant exposure shall not exceed 5/V() J/cm2, where V() is the CIE photopic sensitivity function.

Keywords: radiation damage: light/UV • laser • retina 
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