Electrophysiological retinal pigment epithelium changes observed with indocyanine green, trypan blue and...

Intravitreal application of indocyanine green (ICG), trypan blue (TB) or triamcinolone (TA) during vitreoretinal surgery has been associated with severe damage to the retinal pigment epithelium (RPE). However, the physiological background of these findings remains to be assessed.

In bovine RPE choroid preparations maintained in Ussing chambers, the effect of apical application of ICG, TA (filtered and not filtered) and TB at different concentrations was evaluated. The electrophysiological parameters (transepithelial potential, tissular resistance and short-circuit current) were continuously monitored. The experiments were conducted either in daylight or in dark-adapted conditions.

After apical application of ICG and TA (purified and not purified), all bioelectrical parameters were affected in a dose-dependent manner. No significant changes were observed when the preparations were exposed to daylight. No changes were observed with TB.

The electrophysiological results of apical application may explain the toxic effects observed after intraoperative use of ICG and TA. In this RPE study, TB appears to be the safest visualization aid for vitreoretinal surgery.