Residual indocyanine green evident in eyes of highly myopic patients undergoing vitrectomy surgery

Although several reports about residual indocyanine green (ICG) have been published, high myopia has not been well investigated, and its kinetics are not well understood. A study in the American Journal of Ophthalmology evaluated eyes of highly myopic patients undergoing vitrectomy surgery with ICG-assisted internal limiting membrane (ILM) peeling. The authors found that ICG does accumulate and is evident for up to one month post-operatively. They observe that the accumulation of ICG seemed to depend on the status of the retinal pigment epithelium underlying the posterior retina. They postulate that the retinal pigment epithelial cells may play some role in the deposition of the residual ICG. 
 
It is possible that some eyes are more susceptible to toxic effects, such as highly myopic eyes, eyes with macular detachments or eyes with macular holes in which the ICG will have direct access to the RPE and then may accumulate in the RPE cells. The ICG may then be difficult for the RPE to degrade and may exhibit toxic effects directly on the RPE cells leading to patchy RPE changes and atrophy which has been documented in cases of presumed ICG toxicity. 
 
It may be useful to minimize the exposure of the RPE to the ICG when it is used in cases such as macular hole surgery or in cases in which the macula is detached.