To determine the degree of residual internal limiting membrane (ILM) after idiopathic epiretinal membrane (ERM) peeling and the usefulness of staining with brilliant blue G.
A prospective, multicenter, observational study of 98 eyes undergoing pars plana vitrectomy and membrane peeling for idiopathic ERM. All eyes underwent core vitrectomy (20, 23, or 25 gauge) followed by intravitreal triamcinolone to verify that the posterior hyaloid had been removed. Brilliant blue G (0.2 mL of 0.25 mg/mL) was injected into the vitreous cavity and washed out immediately. The ERM was peeled and then the surgeon observed and recorded the characteristics of the underlying ILM. The posterior pole was restained with brilliant blue G (0.2 mL of 0.25 mg/mL), and the same observations on the characteristics of the ILM were recorded. Peeling of the remaining ILM was performed. The main outcome measured was the status of the ILM after ERM peel. Secondary outcomes included best-corrected visual acuity and central macular thickness at 6 months postoperatively.
After ERM peel, all of the eyes had residual ILM. In 74 eyes, the ILM was present and damaged, whereas in 24 eyes, the ILM was present and undamaged. In 37 eyes, the operating surgeon was unable to determine the status of the ILM before brilliant blue G staining. At 6 months, the logarithm of the minimum angle of resolution best-corrected visual acuity improved from 0.75 ± 0.39 at baseline to 0.31 ± 0.26 (P < 0.0001). The central macular thickness also improved from 460 ± 91 μm at baseline to 297 ± 102 μm (P < 0.003).
Internal limiting membrane is frequently still present after ERM peeling. Staining with brilliant blue G facilitates its identification.