Morphological and functional damage of the retina caused by intravitreous indocyanine green in rat eyes.
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.
Enaida
Hiroshi
H
Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Sakamoto
Taiji
T
Hisatomi
Toshio
T
Goto
Yoshinobu
Y
Ishibashi
Tatsuro
T
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
D004396:Coloring Agents; D007208:Indocyanine Green