title: Transmission of retinal laser wavelengths through blood.
abstract: OBJECTIVE
  Treatment of retinal and choroidal diseases may be influenced by overlying blood. We compared the penetration through blood of various laser wavelengths used in thermal photocoagulation, photodynamic therapy, and transpupillary thermotherapy.
  
  
  METHODS
  Laser light of wavelengths 514 nm, 568 nm, 647 nm, 689 nm, and 810 nm was directed through normal saline (control), whole blood with a hematocrit of 40%, and serial dilutions of whole blood until a steady-state reading of laser power output was obtained. Laser power output was measured with an Orion Laser Power/Energy monitor (Ophir Optronics LTD). Laser power was measured in milliwatts and expressed as a percentage of control.
  
  
  RESULTS
  Five hundred fourteen-nanometer and 568-nm laser wavelengths penetrated the least through all dilutions of blood tested (>60% attenuation through the highest dilution tested); 647-nm, 689-nm, and 810-nm laser wavelengths penetrated most effectively through blood but were still significantly attenuated ( approximately 46%, 49.6%, and 47.0% attenuation, respectively, at the highest dilution tested).
  
  
  CONCLUSIONS
  The presence of hemorrhage may have a significant effect on the delivery of laser energy to underlying structures/tissue. This may affect parameters used in thermal and nonthermal laser treatment of ocular diseases such as choroidal neovascularization.
authors.affiliation: Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Stoltz
authors.forename: Carolyn
authors.initials: C
authors.lastname: Glazer-Hockstein
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Tolentino
authors.forename: Albert M
authors.initials: AM
authors.lastname: Maguire
mesh_terms: D000328:Adult; D001769:Blood / Q000528:radiation effects*; D006801:Humans; D006979:Hyperthermia, Induced; D017075:Laser Coagulation; D008027:Light; D010778:Photochemotherapy