The concept of retinal vital staining is not new.^1–3 There has however been renewed interest in the subject since indocyanine green (ICG) was introduced as a vital stain to highlight the internal limiting membrane (ILM) during macular surgery. ICG’s well known role in cardiac and choroidal angiography exploits its properties as a fluorophore, but its role as a macular vital stain relies on its properties as a chromophore or biological stain. Biological stains such as ICG have specific atomic groupings that impart colour (C = S, C = N, N = N, N = O, and NO₂). ICG is therefore able to stain the thin, optically clear ILM, assisting maculorhexis in much the same way that trypan blue assists capsulorhexis. ICG has more recently been used to help remove epiretinal membranes.⁴

Initial reports were favourable.^5–7 Subsequently, some of the most prominent exponents of ICG reported possible toxicity,⁸ and enthusiasm waned. More recently there have again been papers showing a favourable outcome,^9,10 and the debate continues. The article by Hillenkamp et al in this issue of the BJO (p 437) supports the continued use of ICG, but it should not be read in isolation. This editorial presents the case for and against ICG macular vital staining, considering the clinical and experimental evidence in turn.

Hillenkamp’s study suggests that ICG vital staining is both safe and effective. It reports a retrospective analysis of two consecutive series of patients undergoing removal of epiretinal membranes, with and without the aid of ICG. The strength of this study lies in its …