gms | German Medical Science

The introduction of indocyanine green (ICG) and trypan blue (TB) for staining the epiretinal structures has opened a new field in vitreoretinal surgery, the so-called "chromovitrectomy". However, recent reports have shown adverse effects related to ICG and TB. This study aims to investigate the feasibility to stain the internal limiting membrane (ILM) and the vitreous by alternative dyes belonging to the group of amino di- and triarylmethane. For staining experiments, we used enucleated pig eyes and epiretinal membranes (ERM).

Seventy fresh pig eyes were used after removal of the vitreous body and 0.3 ml of light green (LG), fast green (FG), patent blue (PB), methyl violet (MV), and crystal violet (CV), were injected at the concentration of 0.5 % onto the macula and aspirated after 1 minute. ICG and TB were injected in equal concentrations for comparison with the five dyes previously described. In all eyes the ILM was tried to remove with a gripping membrane forceps. The peeled ILM and the remaining retina were fixed and embedded for light microscopy examination. The entire vitreous of fresh enucleated eyes were placed in a 2 ml of each dye for 1 minute. freshly removed Human ERM were exposed to 1 ml the five dyes at 0.5 %. The intensity of retinal surface and vitreous staining was graded as minimal staining, faint staining (+), moderate staining (++), or strong staining (+++).

Staining of the ILM was with CV strong (+++), with MV and PB moderate (++), with FG faint (+) and with LG minimal. With good visualization of the ILM we achieved an easy ILM-peeling similar to ICG. After staining with CV was the ILM-peeling more difficult. On histological examination we determined deeper layers of the retina on the outside of the ILM. Histological evaluation revealed a successful separation of the fine removed ILM in cases of peeling assisted by PB, FG and MV dyes. Vitreous staining was achieved with all dyes tested in this study. Vitreous staining with CV, FG, PB, and MV showed a moderate (++) staining, and LG a faint (+) staining. Human ERM stained brightly after exposure to PB and FG dyes.

This study demonstrated, that PB and FG in a concentration of 0.5% are excellent alternative dyes to stain the ILM. Further studies are needed to determine the safety for human chromovitrectomy.