Kinetics of indocyanine green dye after intraocular surgeries using indocyanine green staining

Objective: To determine the elimination kinetics of indocyanine green (ICG) after intraocular operations using ICG staining. Methods: Intraocular fluorescence of ICG was determined using the ICG angiographic mode of a scanning laser ophthalmoscope (in vivo) and fluorescence microscopy (in vitro) after circular curvilinear capsulorhexis with ICG staining during cataract surgery and internal limiting membrane (ILM) peeling with ICG staining during macular hole surgery. Subjects: We studied 9 eyes of 7 patients with white cataracts and 14 eyes of 14 patients with idiopathic macular holes. Results: Scanning laser ophthalmoscopy revealed fluorescence in the anterior segment of patients with cataracts on the first postoperative day, and fluorescence remained for a mean ± SD of 6.0 ± 2.2 days postoperatively. Scanning laser ophthalmoscopy also revealed fluorescence in the posterior pole of patients with macular holes, and it remained for a mean ± SD of 2.7 ± 1.4 months postoperatively. Fluorescence microscopy showed fluorescence of the entire tissues, suggesting that ICG had stained not only the surface of the membranes but had also entered them. In both operations, visual outcomes were not significantly different from the results obtained without ICG. Conclusions: Because entire tissues were stained, the differences in ICG kinetics might also be caused by factors other than differences in stainability, such as the environment surrounding the tissues or molecular structural differences between the lens capsule and the ILM. Although we found complete disappearance of fluorescence and good functional recovery, the longer resident time of the dye after macular hole surgery may suggest a potential risk to intraocular tissues.