title: Retinal ganglion cells toxicity caused by photosensitising effects of intravitreal indocyanine green with illumination in rat eyes.
abstract: OBJECTIVE
  To investigate the effects of indocyanine green (ICG) with or without illumination on rat retinal ganglion cells (RGC) and retinal morphology.
  
  
  METHODS
  Intravitreal injections of 1.0 mg/ml ICG solution were performed in rat eyes with or without subsequent illumination for 5 minutes. Eyes in the control group had intravitreal injections of balanced salt solution with illumination. Retrograde labelling of RGC with 6% Fluoro-Gold was performed 1 month later and RGC densities were compared between the three groups. Light microscopy with measurements of outer nuclear layer (ONL) and inner nuclear layer (INL) thicknesses were also performed and compared.
  
  
  RESULTS
  Eyes with ICG without illumination showed insignificant reduction in RGC density compared with the control group (p = 0.28), whereas a significant decrease in RGC density was found in eyes that had ICG injection with illumination (p = 0.036). A significant increase in ONL thickness was also observed in the ICG with illumination treated eyes compared with the ICG without illumination and the control groups (p<0.001). No significant difference in INL thickness was observed between the three groups.
  
  
  CONCLUSIONS
  Intravitreal injection of 0.1 mg/ml ICG in rat eyes followed by illumination resulted in photosensitising toxicity to RGC. Lower ICG concentration or illumination level should be considered when performing ICG assisted macular surgery.
authors.affiliation: Department of Anatomy, University of Hong Kong, Hong Kong SAR, People's Republic of China.
authors.forename: H K F
authors.initials: HK
authors.lastname: Yip
authors.forename: T Y Y
authors.initials: TY
authors.lastname: Lai
authors.forename: K-F
authors.initials: KF
authors.lastname: So
authors.forename: A K H
authors.initials: AK
authors.lastname: Kwok
mesh_terms: D000818:Animals; D002452:Cell Count; D004396:Coloring Agents / Q000633:toxicity; D005260:Female; D007208:Indocyanine Green / Q000633:toxicity*; D007267:Injections; D010775:Photic Stimulation; D017319:Photosensitizing Agents / Q000633:toxicity; D051381:Rats; D012160:Retina / Q000187:drug effects / Q000473:pathology; D012165:Retinal Ganglion Cells / Q000187:drug effects* / Q000473:pathology; D014822:Vitreous Body
chemical_list: D004396:Coloring Agents; D017319:Photosensitizing Agents; D007208:Indocyanine Green