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N Okamoto, T Yanagita, M Nakanishi, S Tanaka, N Ogino, S Uga, K Shimizu; Internal Limiting Membrane (ILM) Stained with Indocyanine Green (ICG) . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2488.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:Today many vitreoretinal surgeons prefer staining the internal limiting membrane (ILM) with Indocyanine green (ICG) while peeling it during macular hole surgery or vitrectomy for macular edema, because it seems safer and more effective. However, it is still unknown exactly which cells or tissues are stained with ICG, and if staining with ICG and/or ILM peeling itself harm the retina. Herein we report on the histopathological results of the peeled ILMs using ICG during vitrectomy. Methods:Thirty-five cases with macular hole were included in this study. These cases underwent ILM peeling using ICG during vitrectomy surgery at Kitasato University Hospital from August 2000 through November 2001. ILMs were peeled using vitreoretinal microforceps after dyeing with 5mg/ml ICG during vitrectomy, immediately frozen to specimens, and observed with a light microscope in a light or dark field condition. Some specimens were fixed with 4% glutaraldehyde and observed with a transmission or scanning electron microscope. Results:Peeled ILMs were observed to be stained only on the side of the vitreous cavity, and not on the other side of the retina. ICG particles were observed to attach to the side of the vitreous cavity, which means the staining we speculated. This observation suggested differences in the characteristics of each side of the ILM. Particle-like substances, which were thought to be small fragments of the retinal cells and myofibroblastic-differentiated cells, were observed on the side of the retina. This observation suggested that the retinal cells, probably Muller cells, were damaged by ILM peeling. Conclusion:The ILM is of uniform structure produced by Muller cells as a basal membrane. It appears that the vitreous side of the ILM is easily attach to ICG particles. That is, the vitreous side of the ILM might be different from the retinal side of the ILM. The myofibroblastic-differentiated cells on the surface of the ILM may play a role in the formation of macular holes and surgical management of macular holes. Also it seems that there is a possibility of damage to the retinal cells including Muller cells, but further investigation is required on the extent and the reversibility of the retinal impairment.
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