Interference microscopy delineates cellular proliferations on flat mounted internal limiting membrane specimens.

Aim: To demonstrate that interference microscopy of flat mounted internal limiting membrane specimens clearly delineates cellular proliferations at the vitreomacular interface. Methods: ILM specimens harvested during vitrectomy were fixed in glutaraldehyde 0.05% and paraformaldehyde 2% for 24 h (pH 7.4). In addition to interference microscopy, immunocytochemistry using antibodies against glial fibrillar acidic protein (GFAP) and neurofilament (NF) was performed. After washing in phosphatebuffered saline 0.1 M, the specimens were flat-mounted on glass slides without sectioning, embedding or any other technique of conventional light microscopy. A cover slide and 49,6-diamidino-2-phenylindole (DAPI) medium were added to stain the cell nuclei. Results: Interference microscopy clearly delineates cellular proliferations at the ILM. DAPI stained the cell nuclei. Areas of cellular proliferation can be easily distinguished from ILM areas without cells. Immunocytochemistry can be performed without changing the protocols used in conventional microscopy. Conclusion: Interference microscopy of flat mounted ILM specimens gives new insights into the distribution of cellular proliferations at the vitreomacular interface and allows for determination of the cell density at the ILM. Given that the entire ILM peeled is seen en face, the techniques described offer a more reliable method to investigate the vitreoretinal interface in terms of cellular distribution compared with conventional microscopy

Chromovitrectomy and the Vitreoretinal Interface

It still remains unclear to which extent the presence and the amount ofretinal debris seen in internal limiting membrane (ILM) specimensharvested during macular surgery for macular holes or epiretinalmembranes are related to the procedure of ILM peeling itself or tomodifications of the surgical technique, such as application of vitaldyes for visualization of the ILM, or to pathological conditions withepiretinal membrane formation at the vitreoretinal interface. Thepresence of cellular fragments on the retinal side of the removed ILMappears to be of multifactorial origin, and additional causes besidesdye application need to be considered. However, morphological studieswith evaluation of vital dyes are still of relevance and provideadditional insights into the ultrastructure of the vitreoretinalinterface and its interaction with adjuvants used during macularsurgery. Chromovitrectomy is an emerging field in vitreoretinal surgery.It is of importance to better understand the tissue-dye interactions,which not only alter the mechanical properties of the tissue beingstained, but may also have an impact on the functional resultpostoperatively

Epiretinale Membranen

Bei der Fixierung immunzytochemischer Präparate lässt sich sowohl durch Kryomethoden als auch durch milde chemische Fixierungen potentiell die Antigenität erhalten. Inwieweit die Ultrastruktur epiretinaler Membranen (ERM) durch Verwendung dieser Präparationsverfahren erhalten bleibt, ist unklar. Durch Pars-plana-Vitrektomie wurden epiretinale Membranen von 15 Patienten mit Makula pucker entnommen. Zum einen wurden ERM in einem Gemisch aus 2% Paraformaldehyd und 0,05% Glutaraldehyd ohne Osmiumtetroxid bei 4°C chemisch fixiert. Zum anderen wurden Proben durch Plunging oder Impact Freezing in flüssigem Stickstoff unter Gefrierschutz mit 1-Hexadecene und 40% Saccharose kryofixiert. Filterpapier diente als Trägersubstanz bei der Durchführung der Kryofixierung. Die Dehydrierung und Einbettung erfolgte in Aceton und Unicryl bzw. Unicryl-ähnlichem Medium. Die Transmissionselektronenmikroskopie zeigte, dass die innere Grenzmembran (ILM) der Retina und Kollagenfibrillen durch die Kryofixierung gut erhalten bleibt. Zelluläre Details konnten jedoch nicht dargestellt werden. Im Gegensatz dazu erlaubte die milde chemische Fixierung ERM die präzise Darstellung sowohl von ILM und Kollagen als auch von zellulären Strukturen wie Kernmembranen, Nukleoli, Chromatin und zytoplasmatischen Mikrofilamenten. Das Filterpapier als Trägersubstanz beschränkte aufgrund von Eiskristallbildung die Kryofixierung epiretinaler Membranen. Um die Ultrastruktur für immunzytochemische Untersuchungen zuverlässig zu erhalten, wird die milde chemische Fixierung in 2% Paraformaldehyd und 0,05% Glutaraldehyd empfohlen. Es werden weitere Studien benötigt, die den Erhalt der Antigenität epiretinalen Gewebes nach Kryofixierung und milder Aldehyd-Fixierung im Zusammenhang mit verschiedenen Dehydrierungs- und Einbettungsverfahren untersuchen

Sequential epiretinal membrane removal with internal limiting membrane peeling in brilliant blue G-assisted macular surgery

Purpose To assess the selectivity of brilliant blue G (BBG) staining by analysing the morphological components of unstained and stained tissue obtained during epiretinal membrane (ERM) removal with internal limiting membrane (ILM) peeling in BBG-assisted macular surgery. Methods Twenty-six surgical specimens were removed from 13 eyes with epiretinal gliosis during vitrectomy using BBG for ERM and ILM peeling. We included eyes with idiopathic macular pucker, idiopathic macular hole and vitreomacular traction syndrome. The dye was injected into the fluid-filled globe. Unstained and stained epiretinal tissue was harvested consecutively and placed into separate containers. All specimens were processed for conventional transmission electron microscopy. Results The first surgical specimen of all eyes showed no intraoperative staining with BBG and corresponded to masses of cells and collagen. The second surgical specimen demonstrated good staining characteristics and corresponded to the ILM in all patients included. In seven eyes, the ILM specimens were seen with minor cell proliferations such as single cells or a monolayer of cells. Myofibroblasts, fibroblasts and astrocytes were present. In five cases, native vitreous collagen fibrils were found at the ILM. In six of the eyes, ILM specimens were blank. Conclusion Our clinicopathological correlation underlines the selective staining properties of BBG. The residual ILM is selectively stained by BBG even when a small amount of cells and collagen adheres to its vitreal side. To reduce the retinal exposure to the dye, the surgeon might choose to remove the ERM without using the dye, followed by a BBG injection to identify residual ILM

Chromovitrectomy and the Vitreoretinal Interface

It still remains unclear to which extent the presence and the amount ofretinal debris seen in internal limiting membrane (ILM) specimensharvested during macular surgery for macular holes or epiretinalmembranes are related to the procedure of ILM peeling itself or tomodifications of the surgical technique, such as application of vitaldyes for visualization of the ILM, or to pathological conditions withepiretinal membrane formation at the vitreoretinal interface. Thepresence of cellular fragments on the retinal side of the removed ILMappears to be of multifactorial origin, and additional causes besidesdye application need to be considered. However, morphological studieswith evaluation of vital dyes are still of relevance and provideadditional insights into the ultrastructure of the vitreoretinalinterface and its interaction with adjuvants used during macularsurgery. Chromovitrectomy is an emerging field in vitreoretinal surgery.It is of importance to better understand the tissue-dye interactions,which not only alter the mechanical properties of the tissue beingstained, but may also have an impact on the functional resultpostoperatively

An in vivo evaluation of Brilliant Blue G in animals and humans

Background/Aims: To evaluate the retinal toxicity of Brilliant Blue G (BBG) following intravitreal injection in rat eyes and examine the biocompatibility and the staining properties in humans.Methods: BBG was injected into the 11 rat eyes to evaluate toxic effects with balanced salt solution (BSS) serving as control. Retinal toxicity was assessed by retinal ganglion cell (RGC) counts and by light microscopy 7 days later. In addition, BBG was applied during vitrectomy for macular hole (MH) (n = 15) or epiretinal membranes (ERM) (n = 3) in a prospective, non-comparative consecutive series of patients. Before and after surgery, all patients underwent a complete clinical examination including measurement of best corrected visual acuity (VA) and intraocular pressure, perimetry, fundus photography and optical coherence tomography. Patients were seen 1 day before surgery and then in approximately four weeks intervals.Results: No significant reduction in RGC numbers and no morphological alterations were noted. A sufficient staining of the internal limiting membrane (ILM) was seen in patients with MH, while the staining pattern in ERM cases was patchy, indicating that parts of the ILM were peeled off along with the ERM in a variable extent. All MHs could be closed successfully. VA improved in 10 eyes (56%; 8/15 MH patients, 2/3 ERM patients), was unchanged in four eyes (22%; all MH patients) and was reduced in four eyes (22%; 3/15 MH, 1/3 ERM). No toxic effects attributable to the dye were noted during patient follow-up. The ultrastructure of tissue harvested during surgery was unremarkable.Conclusion: Brilliant Blue provides a sufficient and selective staining of the ILM. No retinal toxicity or adverse effects related to the dye were observed in animal and human studies. The long-term safety of this novel dye will have to be evaluated in larger patient series and a longer follow-up

Epiretinal Cell Proliferation in Macular Pucker and Vitreomacular Traction Syndrome: Analysis of Flat-Mounted Internal Limiting Membrane Specimens

Purpose: To describe new details of epiretinal cell proliferation in flat-mounted internal limiting membrane specimens. Methods: One hundred nineteen internal limiting membrane specimens were removed en bloc with epiretinal membranes from 79 eyes with macular pucker (MP) and 40 eyes with vitreomacular traction syndrome. Intraoperatively, posterior vitreous detachment was assessed as complete or incomplete. Whole specimens were flat-mounted on glass slides and processed for interference and phase-contrast microscopy, cell viability assay, and immunocytochemistry. Results: Mean cell viability percentage was higher in MP than in vitreomacular traction syndrome. Two cell distribution patterns were found. Anti-CD163 labeling presented predominantly in MP with complete posterior vitreous detachment. CD45 expression was similar in all groups of diagnosis. Anti-glial fibrillary acidic protein (GFAP) labeling was found in MP irrespective of the extent of posterior vitreous detachment. Alpha-SMA (alpha-smooth muscle actin) labeling was mainly presented in MP with incomplete posterior vitreous detachment and in vitreomacular traction syndrome. Simultaneous antibody labeling included GFAP/CD45, GFAP/CD163, CD163/CD45, and CD163/alpha-SMA. Conclusion: Hyalocytes constitute a major cell type of epiretinal cell proliferation in eyes with MP and vitreomacular traction syndrome. Glial cells, notably retinal Muller cells, are involved as well. It appears that transdifferentiation of cells in vitreomacular traction might be more frequent than previously thought and that those cells possess a greater variability of immunocytochemical properties than expected. RETINA 33:77-88, 201

Cell composition at the vitreomacular interface in traumatic macular holes

PURPOSE To describe characteristics of the vitreomacular interface (VMI) in traumatic macular holes (TMH) compared to idiopathic macular holes (IMH) using immunofluorescence and electron microscopy, and to correlate with clinical data. METHODS For immunocytochemical and ultrastructural analyses, premacular tissue with internal limiting membrane (ILM) and epiretinal membrane (ERM) was harvested during vitrectomy from 5 eyes with TMH and 5 eyes with IMH. All specimens were processed as flat mounts for phase-contrast microscopy, interference and fluorescence microscopy, and transmission electron microscopy (TEM). Primary antibodies were used against microglial and macroglial cells. Clinical data was retrospectively evaluated. RESULTS Surgically excised premacular tissue of eyes with TMH showed a less pronounced positive immunoreactivity for anti-glutamine synthetase, anti-vimentin and anti-IBA1 compared to eyes with IMH. Cell nuclei staining of the flat-mounted specimens as well as TEM presented a lower cell count in eyes with TMH compared to IMH. All detected cells were found on the vitreal side of the ILM. No collagen fibrils were seen in specimens of TMH. According to patients' age, intraoperative data as well as spectral-domain optical coherence tomography (SD-OCT) analysis revealed an attached posterior vitreous in the majority of TMH cases (60%), whereas all eyes with IMH presented posterior vitreous detachment. CONCLUSION The vitreomacular interface in TMH and IMH shows significant differences. In TMH, glial cells are a rare finding on the vitreal side of the ILM

Optical coherence tomography-based consensus definition for lamellar macular hole.

BackgroundA consensus on an optical coherence tomography definition of lamellar macular hole (LMH) and similar conditions is needed.MethodsThe panel reviewed relevant peer-reviewed literature to reach an accord on LMH definition and to differentiate LMH from other similar conditions.ResultsThe panel reached a consensus on the definition of three clinical entities: LMH, epiretinal membrane (ERM) foveoschisis and macular pseudohole (MPH). LMH definition is based on three mandatory criteria and three optional anatomical features. The three mandatory criteria are the presence of irregular foveal contour, the presence of a foveal cavity with undermined edges and the apparent loss of foveal tissue. Optional anatomical features include the presence of epiretinal proliferation, the presence of a central foveal bump and the disruption of the ellipsoid zone. ERM foveoschisis definition is based on two mandatory criteria: the presence of ERM and the presence of schisis at the level of Henle's fibre layer. Three optional anatomical features can also be present: the presence of microcystoid spaces in the inner nuclear layer (INL), an increase of retinal thickness and the presence of retinal wrinkling. MPH definition is based on three mandatory criteria and two optional anatomical features. Mandatory criteria include the presence of a foveal sparing ERM, the presence of a steepened foveal profile and an increased central retinal thickness. Optional anatomical features are the presence of microcystoid spaces in the INL and a normal retinal thickness.ConclusionsThe use of the proposed definitions may provide uniform language for clinicians and future research