Abstract
Abstract: :
Purpose: Patients after ICG-assisted vitrectomy for macular pucker seem to have less functional benefit postoperatively. This study was performed to compare the ultrastructure of tissue removed during vitrectomy for macular pucker with and without the use of ICG. Methods: Epiretinal tissue of 16 patients after ICG-assisted vitrectomy and of 6 patients without intraoperative ICG application was harvested during standard pars plana vitrectomy. Specimens were placed in 4% glutaraldehyde. The tissue was then postfixed with Dalton´s fixative (osmium 2%), dehydrated, and embedded in Epon. Semithin sections were stained with 2% toluidine blue. Ultrathin sections were obtained from all specimens, contrasted with uranyl acetate and lead citrate, and analyzed using a Zeiss EM 9 electron microscope (Zeiss Jena, Germany). No modification of the surgical technique except the use of ICG (<0.5%, 275 mOsm, pH 7.5) was made. Results: Light microscopy of all specimens showed continuous pieces of ILM. Adherent to the vitreal surface of the ILM we observed fibrous-cellular layers consistent with previous findings in epiretinal tissue removed during macular pucker surgery. Additionally, electron microscopy revealed cellular elements on the retinal side of the ILM in all specimens which had been stained with ICG. These structures were identified as plasma membranes of Mueller cells and other undetermined retinal structures. There were no obvious differences concerning these findings between patients with and without postoperative visual field defects. In contrast, only very few cellular elements were found on the retinal side of the ILM when ICG had not been used for staining. Conclusion: The reported morphological findings indicating a deeper cleavage plane may explain the less favorable functional outcome following ICG-assisted peeling. As single patients showed an increase in postoperative visual acuity, it seems not likely, that the disruption of Mueller cells is the only factor responsible for the postoperative results observed. Further studies will be needed to evaluate the influence of ICG on the human retina. None.
Keywords: 460 macula/fovea • 507 pathology: human