Aims: To develop an intraoperative, extraocular ICG dye staining test (IE-ICG) for the differentiation of a peeled ILM from a thin epiretinal membrane, and to evaluate its efficacy.
Methods: A consecutive observational case and laboratory observational series. We performed ILM peeling in patients with an idiopathic macular hole (MH, n=10) and diabetic macular edema (DME, n=10) without vital dye staining such as indocyanin green or trypan blue. We also performed membrane peeling in patients with an idiopathic epiretinal membrane (ERM, n=10). Then, the peeled membranes were stained with ICG (1.25mg/ml) beyond the operation field and examined them under a light microscope. After this examination, membranes were fixed with glutaraldehyde and electron microscope was performed to confirm whether they were ILMs or thin ERM. The concordance rates between surgeon's intraoperative impression of membranes (SI), IE-ICG results (IT) and histologic findings (HF) of peeled membranes were evaluated to reveal the efficacy of IE-ICG.
Results: The ILMs were homogenously stained with ICG dye (posivite IE-ICG) and the ERMs were not stained at all by ICG dye (negative IE-ICG). The concordance rate between IT and HF was 100% in all three groups of patients. However, concordance rates between SI and IT were 100% in MH, 80% in DME, and 50% in ERM, respectively. Surgeon's impression of membrane is inaccurate especially in patients with idiopathic epiretinal membrane.
Conclusion: Considering the cost, difficulties of tissue preparation, and the time consuming process of histologic confirmation of an ILM, IE-ICG may be a useful alternative for the differentiation of a peeled ILM and a thin ERM.
- ICG dye test
- epiretinal membrane
- internal limiting membrane
- new method