Toxicity of indocyanine green injected into the subretinal space: subretinal toxicity of indocyanine green.

PURPOSE

To evaluate the toxicity of indocyanine green (ICG) injected into the subretinal space. Indocyanine green may come in contact with photoreceptors and retinal pigment epithelium through a macular hole during ICG-assisted peeling of the internal limiting membrane.

METHODS

Balanced salt solution or ICG of various concentrations (0.6, 1.25, 2.5, or 5.0 mg/mL) was injected into the subretinal space of rabbit eyes and removed after 1 minute. After 3 days, 1 week, and 4 weeks, the eyes were enucleated and evaluated by light microscopy and electron microscopy.

RESULTS

When the ICG of 1.25 mg/mL or higher concentration was injected into the subretinal space, degenerative changes of the photoreceptors and the retinal pigment epithelial cells were found after 3 days with light and electron microscopy. After 1 week, the outer retina was disintegrated and the photoreceptors were not found. After 4 weeks in the eyes with 1.25 mg/mL ICG, short photoreceptors and a thin outer nuclear layer were seen. In the eyes with 2.5 mg/mL or higher ICG, the photoreceptors and the outer nuclear layer were destroyed completely.

CONCLUSION

The results of this study suggest that the ICG of 1.25 mg/mL or higher concentration has toxicity to the outer retina of the rabbit and may cause adverse effects on the functional outcome after macular hole surgery.