title: Morphological and functional damage of the retina caused by intravitreous indocyanine green in rat eyes.
abstract: 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Enaida
authors.forename: Taiji
authors.initials: T
authors.lastname: Sakamoto
authors.forename: Toshio
authors.initials: T
authors.lastname: Hisatomi
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Goto
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Ishibashi
mesh_terms: D000818:Animals; D004396:Coloring Agents / Q000633:toxicity*; D004596:Electroretinography / Q000187:drug effects; D007208:Indocyanine Green / Q000633:toxicity*; D008297:Male; D051381:Rats; D011914:Rats, Inbred BN; D012160:Retina / Q000187:drug effects* / Q000473:pathology / Q000503:physiopathology; D012164:Retinal Diseases / Q000139:chemically induced* / Q000473:pathology / Q000503:physiopathology; D014821:Vitrectomy; D014822:Vitreous Body
chemical_list: D004396:Coloring Agents; D007208:Indocyanine Green