Morphological and functional damage of the retina caused by intravitreous indocyanine green in rat eyes

Graefes Arch Clin Exp Ophthalmol. 2002 Mar;240(3):209-13. doi: 10.1007/s00417-002-0433-7. Epub 2002 Feb 15.


Background: This study was designed to investigate the influence of intravitreal indocyanine green (ICG) on retinal morphology and function.

Methods: Brown Norway rats eyes ( n=24) were vitrectomized by the injection of 0.05 ml of 100% SF(6) gas. Two weeks later, ICG solution was injected into the vitreous cavity of vitrectomized eyes at a dose of 25 mg/ml, 2.5 mg/ml, 0.25 mg/ml or 0.025 mg/ml (0.05 ml/eye). Retinal toxicity was histologically assessed by light microscopy on day 10. The retinal function was also evaluated by electroretinography (ERG) in the low-dose groups (0.25 mg/ml and 0.025 mg/ml) after 10 days and again after 2 months,. Sham-operated eyes (SF(6) injected followed by 0.05 ml of BSS plus, n=6) were used as controls.

Results: In the high-dose group (25 mg/ml ICG), the retinal structure was severely deformed and the retinal pigment epithelium partly disappeared. In eyes with 2.5 mg/ml ICG, the retinal structure was also affected but less strongly so than with 25 mg/ml. No apparent pathologic change was observed in the low-dose groups (0.25 mg/ml or 0.025 mg/ml) by light microscopy. In contrast, 10 days later the amplitude of dark-adapted a- and b-waves of ERGs in the eyes of low-dose group rats were found to have decreased. In addition the light-adapted b-waves did not change significantly. These changes remained for 2 months.

Conclusion: Even at a low dose (0.025 mg/ml), intravitreous ICG induced functional damage of the retina without any apparent morphological damage. This information should be taken into account when clinically administering ICG into the vitreous cavity.

MeSH terms

  • Animals
  • Coloring Agents / toxicity*
  • Electroretinography / drug effects
  • Indocyanine Green / toxicity*
  • Male
  • Rats
  • Rats, Inbred BN
  • Retina / drug effects*
  • Retina / pathology
  • Retina / physiopathology
  • Retinal Diseases / chemically induced*
  • Retinal Diseases / pathology
  • Retinal Diseases / physiopathology
  • Vitrectomy
  • Vitreous Body


  • Coloring Agents
  • Indocyanine Green