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Journal of Biomedical Optics • Open Access

Retinal safety of near-infrared lasers in cataract surgery

Paper Abstract

Femtosecond lasers have added unprecedented precision and reproducibility to cataract surgery. However, retinal safety limits for the near-infrared lasers employed in surgery are not well quantified. We determined retinal injury thresholds for scanning patterns while considering the effects of reduced blood perfusion from rising intraocular pressure and retinal protection from light scattering on bubbles and tissue fragments produced by laser cutting. We measured retinal damage thresholds of a stationary, 1030-nm, continuous-wave laser with 2.6-mm retinal spot size for 10- and 100-s exposures in rabbits to be 1.35 W (1.26 to 1.42) and 0.78 W (0.73 to 0.83), respectively, and 1.08 W (0.96 to 1.11) and 0.36 W (0.33 to 0.41) when retinal perfusion is blocked. These thresholds were input into a computational model of ocular heating to calculate damage threshold temperatures. By requiring the tissue temperature to remain below the damage threshold temperatures determined in stationary beam experiments, one can calculate conservative damage thresholds for cataract surgery patterns. Light scattering on microbubbles and tissue fragments decreased the transmitted power by 88% within a 12 deg angle, adding a significant margin for retinal safety. These results can be used for assessment of the maximum permissible exposure during laser cataract surgery under various assumptions of blood perfusion, treatment duration, and scanning patterns.

Paper Details

Date Published: 14 September 2012
PDF: 3 pages
J. Biomed. Opt. 17(9) 095001 doi: 10.1117/1.JBO.17.9.095001
Published in: Journal of Biomedical Optics Volume 17, Issue 9
Show Author Affiliations
Jenny Wang, Stanford Univ. (United States)
Christopher Sramek, Stanford Univ. (United States)
Yannis M. Paulus, Stanford Univ. School of Medicine (United States)
Daniel Lavinsky, Stanford Univ. School of Medicine (United States)
Georg Schuele, OptiMedica Corp. (United States)
Dan E. Andersen, OptiMedica Corp. (United States)
David A. Dewey, OptiMedica Corp. (United States)
Daniel V. Palanker, Stanford Univ. (United States)

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