Transfer of Indocyanine Green into the Optic Nerve After Intravitreal Application in the Rabbit Eye

Abstract

Abstract: : Purpose: To investigate whether indocyanine green (ICG) migrates into the optic nerve after intravitreal application. Methods: Gas vitrectomy was performed in one eye of adult pigmented rabbits by the pars plana injection of 0.4 ml of 100% C₃F₈ (n=10). One week later, vitrectomy was performed and 0.2 ml of 0.25% ICG was instilled into the vitreous cavity of vitrectomized eyes. After 30 seconds of ICG application, the vitreous cavity was rinsed with BSS plus solution. Non-operated rabbits served as control group (n=2). Globes and visual pathways as well as the entire brain were removed, and ICG fluorescence of the specimens was examined with a digital fundus camera starting from the1^st day upto the 4^th week after the surgery. Results: No fluorescein was detected at all in the visual pathways and the brain of the control group of rabbits. Optic nerve adjacent to the ICG instilled eye was stained diffusely ICG starting from the 1^st day after surgery. Fluorescence extended along the intraorbital portion of the optic nerve and ICG never reached to the optic chiasm. At the 4^th postoperative week, ICG signal was still detected, but staining was less intense. Conclusions: Intravitreally injected ICG transfers into the optic nerve in the rabbit eye.

Keywords: vitreoretinal surgery • injection • imaging methods (CT, FA, ICG, MRI, OCT, RTA, S