Purpose  

To investigate the effects of subretinal indocyanine green (ICG) on retinal morphology in rabbit eyes.

Methods  

Retinal bleb detachments were produced by injections of ICG at dosages of 25 mg/ml, 5 mg/ml, and 0.5 mg/ml or with an injection of balanced salt solution (BSS) into the subretinal space of albino rabbit eyes. Morphological change was assessed by light and transmission electron microscopy from the viewpoint of dose and time. Some sections were also probed with the TUNEL technique to detect apoptotic cells.

Results  

At 14 days after subretinal injection of BSS and 0.5 mg/ml ICG, the structure of the retina was well preserved. However, injections of 5 mg/ml or 25 mg/ml caused thinning of the retina, especially loss of the outer retinal layer. In eyes injected with 5 mg/ml ICG, the photoreceptors began disappearing within 3 days after the injection and over time showed the development of retinal atrophy. TUNEL-positive cells appeared abundantly in the photoreceptor layers 1 and 3 days after the injection of 5 mg/ml ICG. Transmission electron microscopy confirmed apoptosis in the photoreceptors.

Conclusion  

These data indicate that subretinal ICG induces apparent morphological damage of the retina in a dose-dependent manner.