The majority of vitreoretinal surgeons use dyes to stain the internal limiting membrane (ILM) and/or epiretinal membranes.1Dyes are mostly used to assist surgeons during macular hole and pucker surgery, with the gold standard for such procedures being indocyanine green (ICG).
ICG selectively stains the ILM and the large majority of vitreoretinal surgeons are quite comfortable with this dye, because it improves the safety and ease of ILM peeling, whilst also saving time during surgery. Functional improvement with ICG compared with ILM peeling without ICG is discussed controversially,2 with some reports even urging caution when using ICG, because of the risk of adverse effects on the retina.3 The use of alternative dyes, such as trypan blue, is also questionable, primarily because this dye is thought to be less well tolerated by the retina than ICG.4
Recently, a Japanese group tested a new dye, Brilliant Blue G (BBG), which shows a better biocompatibility than ICG.5
Why is it better than ICG?
From their studies with the dye, Hiroshi Enaida, MD and colleagues found that BBG is non-toxic to the retina in concentrations from 1 to 10 mg/ml. Since it is a non-fluorescent dye, the presence of light toxicity, such as that found in ICG, is highly unlikely. The staining of the ILM is comparable to ICG, however, the BBG concentration required for ILM staining in primates (0.5 mg/ml) is one tenth of that required for ICG (5 mg/ml). Moreover, Dr Enaida has more recently published a clinical study showing that a concentration of 0.25 mg/ml of BBG is sufficient to stain ILM.6 BBG is also now being used as a stain for the lens capsule.7
The use of BBG for chromovitrectomy is patented8 and is also EC-approved.