Effect of Intravitreal Injection of Indocyanine Green, Triamcinolone Acetonide and Trypan Blue on the Electroretinographic Response of Rats

Abstract

Purpose:: Indocyanine Green (ICG) and Tripan Blue (TB) are commonly used in macular surgery by making easier the internal limiting membrane (ILM) removing. However, the innocuousness of these dyes is not actually established notably for ICG. Then, several authors proposed the use of triamcinolone acetonide (TA) as an alternative to the use of intraoperative dyes for visualizing the ILM. The purpose of this study was to evaluate the effects of intravitreal injection of ICG, TB and TA on the rat electroretinogram (ERG).

Methods:: Three groups of 12-week-old Sprague Dawley rats (n=6) received intravitreal injection in one eye of 0.1mL of either ICG 0.5mg/mL, TB 3mg/mL or TA 40mg/mL followed by a rinse using a 1mL of saline solution. The controlateral eye was used as a control and was injected similarly with a saline solution only. The scotopic ERG was recorded at different intensities (10mcds/m², 2500mcds/m² and 25000mcds/m²) before injection and 28 days after treatment.

Results:: No effect of the treatment was observed on the ERG amplitudes and wave latencies in control eyes and in eyes treated with TB and TA. The ERG b-wave amplitudes and latencies were significantly reduced in eyes treated with ICG at 10mcds/m² and 2500mcds/m² but not at 25000mcds/m² (amplitude means: t₀=174.8µV versus t₂₈=55.0µV at 10mcds/m² p<0.05; t₀=176.5µV versus t₂₈=70.0µV at 2500mcds/m² p<0.05; t₀=140.3µV versus t₂₈=40.0µV at 25000mcds/m² p=0.057). The ERG a-wave amplitudes and latencies were also significantly lower at 2500mcds/m² in eyes treated with ICG (amplitude means: t₀=45.0µV versus t₂₈=23µV p<0.05; latency means: t₀=7.6msec versus t₂₈=9.5msec p<0.01).

Conclusions:: This study shows a negative effect of ICG on retinal function one month after a transient retinal exposure. TA and TB could be considered as an interesting alternative to ICG for macular surgery.

Keywords: retina • drug toxicity/drug effects • electroretinography: non-clinical