Staining of the intraocular structures during surgery facilitatesanterior and posterior segment surgery, in anterior segment surgery,when retroillumination is absent; a controlled capsulorhexisbecomes difficult due to reduced visibility of the developing anteriorcapsular flap.Staining of the lens structures with the use of several dyesincluding indocyanine green, trypan blue, fluorescein sodium, andgentian violet facilitates these maneuvers during cataract surgery.In posterior segment surgery dyes have been used to stain thevitreous, internal limiting membrane (ILM), and epiretinalmembranes (ERM). This provides a contrast between the stainedmembrane and the unstained retina.