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Malav Joshi, Raymond Iezzi; Redistribution of indocyanine green dye after pars plana vitrectomy with epiretinal membrane peel surgery. Invest. Ophthalmol. Vis. Sci. 2017;58(8):2801.
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© ARVO (1962-2015); The Authors (2016-present)
The fate of residual indocyanine green (ICG) dye used to aid in epiretinal membrane (ERM) peeling during pars plana vitrectomy (PPV) surgery is not well-established. Our goal is to understand how this residual dye interacts and redistributes within the retinal and choroidal tissues post-vitrectomy.
Retained ICG dye was imaged post-vitrectomy via ICG fluorescence (ICG-F) scanning laser ophthalmoscopy in two eyes of two patients without intravenous ICG dye injection. Both patients underwent PPV with ICG dye staining and ERM peeling, without intravitreal gas. The ICG dye was reconstituted using dextrose 5% water and applied to the retinal surface for 60 seconds. ERM was removed using a pinch-and-peel technique, without ILM peeling. In both patients, ICG-F images were obtained on postoperative week one (POW1). In one patient, the images were obtained on postoperative day (POD1) as well.
We found evidence of residual ICG dye present after vitrectomy as seen by the hyperfluorescence (HF) on the ICG-F images. These images demonstrate that some of the residual dye gets absorbed in the deep retina or retinal pigment epithelium (RPE) on postoperative day one. This created a pattern of fundus HF that correlated with the area where the dye was applied. ICG-F images demonstrate that the ICG retro-illuminated the residual macular pucker, highlighting the inner-retinal features. On POW1, however, the uniform pattern of ICG-F was reduced and the fluorescence migrated into the retinal nerve fiber layer (RNFL) and the optic nerve (ON).
This redistribution of ICG dye from the outer retina/RPE/choroid to the retinal nerve fiber layer and ON in the postoperative period is an interesting and unexpected finding. ICG has lipid and aqueous-soluble domains, allowing portions of the molecule to reside in the plasma membrane and cytosol of neurons such as retinal ganglion cells. It is also a voltage sensitive dye that demonstrates action potential-dependent fluorescence. Consequently, the finding that ICG enters retinal ganglion cells may permit imaging of this voltage sensitive dye to assess retinal ganglion cell function. A larger case series with longer follow-up is needed to elucidate the mechanism of this finding and its potential diagnostic applications.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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