title: Retinal injury thresholds for 532, 578, and 630 nm lasers in connection to photodynamic therapy for choroidal neovascularization.
abstract: OBJECTIVE
  The purpose of this study was to explore the retinal injury thresholds in rabbits and evaluate the influence of retinal pigmentation on threshold irradiance at laser wavelengths of 532, 578, and 630 nm which might be involved in hypocrellin B (HB) and hematoporphyrin monomethyl ether (HMME) photodynamic therapy (PDT) for choroidal neovascularization (CNV).
  
  
  METHODS
  The eyes of pigmented and non-pigmented rabbits were exposed to 532, 578, and 630 nm lasers coupled to a slit lamp biological microscope. The exposure duration was 100 seconds and the retinal spot size was 2 mm throughout the experiment. The minimum visible lesions were detected by funduscopy at 1 and 24 hours post exposure. Bliss probit analysis was performed to determine the ED50 thresholds, fiducial limits and probit slope.
  
  
  RESULTS
  In pigmented rabbits, the 24-hour retinal threshold irradiances at 532, 578, and 630 nm were 1,003, 1,475, and 1,720 mW/cm(2) , respectively. In non-pigmented rabbits, the 24-hour threshold irradiances were 1,657, 1,865, and 15,360 mW/cm(2) , respectively. The ED50 for 24-hour observation differed very little from the ED50 for 1-hour observation. The non-pigmented rabbits required a ninefold increase in threshold irradiance at 630 nm comparing to the pigmented rabbits.
  
  
  CONCLUSIONS
  This study will contribute to the knowledge base for the limits of laser irradiance in application of HB or HMME PDT for CNV.
authors.affiliation: Department of Dermatology, The First Affiliated Hospital of Chinese PLA General Hospital, Beijing, 100048, P.R. China.
authors.forename: Hongxia
authors.initials: H
authors.lastname: Chen
authors.forename: Zaifu
authors.initials: Z
authors.lastname: Yang
authors.forename: Xianbiao
authors.initials: X
authors.lastname: Zou
authors.forename: Jiarui
authors.initials: J
authors.lastname: Wang
authors.forename: Jianguo
authors.initials: J
authors.lastname: Zhu
authors.forename: Ying
authors.initials: Y
authors.lastname: Gu
mesh_terms: D000818:Animals; D020256:Choroidal Neovascularization / Q000188:drug therapy*; D006415:Hematoporphyrins / Q000627:therapeutic use*; D007834:Lasers / Q000009:adverse effects*; D054020:Lasers, Gas / Q000009:adverse effects / Q000627:therapeutic use; D054023:Lasers, Semiconductor / Q000009:adverse effects / Q000627:therapeutic use; D053844:Lasers, Solid-State / Q000009:adverse effects / Q000627:therapeutic use; D010569:Perylene / Q000031:analogs & derivatives* / Q000627:therapeutic use; D010778:Photochemotherapy / Q000009:adverse effects* / Q000379:methods; D017319:Photosensitizing Agents / Q000627:therapeutic use*; D011809:Quinones / Q000627:therapeutic use*; D011817:Rabbits; D011897:Random Allocation; D012160:Retina / Q000293:injuries*
chemical_list: D006415:Hematoporphyrins; D017319:Photosensitizing Agents; D011809:Quinones; C494379:hematoporphyrin monomethyl ether; D010569:Perylene; C064522:hypocrellin B
keywords: injury thresholds; lasers; photodynamic therapy; retina