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Arnd Gandorfer

Publications and source records attributed to Arnd Gandorfer.

At least 19 recordsLinked to original sources
PubMed2006

Ultrastructure of the vitreomacular interface in full-thickness idiopathic macular holes: a consecutive analysis of 100 cases.

PURPOSE: To evaluate the ultrastructure of the vitreoretinal interface in stage III and stage IV idiopathic macular holes. DESIGN: A consecutive observational case series, laboratory investigation. METHODS: Pars plana vitrectomy with en-bloc removal of the internal limiting membrane (ILM) and epimacular tissue was performed by one surgeon in 80 eyes with stage III macular holes and in 20 eyes with stage IV macular holes. In total, 218 specimens were processed for light and transmission electron microscopy. RESULTS: Fibrocellular proliferation at the vitreal side of the ILM was found in 57 cases. Native vitreous collagen (NVC) was attached to the ILM in 36 eyes. The presence of NVC was considerably more frequent in eyes with stage IV (70%) than in eyes with stage III macular holes (26%). Mono- and multilayered cellular membranes were seen more frequently in stage IV macular holes. NVC, if present, was always associated with fibrocellular proliferation. In 39 eyes with stage III and in four eyes with stage IV macular holes, the ILM was devoid of any cells and collagen. CONCLUSIONS: Fibrocellular proliferation appears to be a secondary event instead of a primary feature in macular hole development. The severity of fibrocellular proliferation is associated with the presence of NVC. Incomplete vitreoretinal separation may contribute to the development of epimacular membranes in eyes with idiopathic macular holes. Remnants of the vitreous cortex remain more often attached to the ILM in eyes with spontaneous posterior vitreous detachment (PVD) than in eyes with surgical PVD induction.

Aged↗
PubMed2006

Evaluation of the internal limiting membrane after conventional peeling during macular hole surgery.

We evaluated the histologic features of the internal limiting membrane (ILM) of the retina removed during macular hole surgery without indocyanine green staining. Our investigation focused on the presence or absence of retinal structures adherent to the retinal surface of the ILM. Because only tiny retinal cellular fragments were observed especially in ILM folds, we conclude that conventional ILM peeling can be performed safely with a cleavage plane between the retinal surface of the ILM and Müller cell endfeet.

Aged↗
PubMed2005

Pulsed electron avalanche knife (PEAK-fc) for dissection of retinal tissue.

OBJECTIVE: To evaluate the effectiveness and precision of tractionless retinal tissue dissection by the advanced version of the pulsed electron avalanche knife for fine cutting (PEAK-fc; Carl Zeiss Meditec, Jena, Germany). METHODS: Porcine retina (in vivo) and human retina (in vitro) were incised with the PEAK-fc using various pulse parameters. The globes were then processed for light microscopy. Evaluation of all specimens focused on depth of the retinal cuts and on the degree of collateral damage. RESULTS: Retinal cuts performed both in vivo on porcine eyes and on human donor eyes showed very sharp edges with only little collateral damage. With probes of 600 mum in length, the optimal pulse parameters for precise and reproducible cutting of the retina were an amplitude of 350 to 380 V, a repetition rate of 300 Hz, and 30 "minipulses" per pulse of 100-microsecond duration. With increasing voltage, cuts also affected the retinal pigment epithelium and the choroid, followed by intravitreal bleeding during in vivo application. CONCLUSION: We demonstrated that PEAK-fc is capable of precisely cutting retinal tissue in vivo and in vitro using optimal pulse parameters. Further in vivo studies will be necessary to determine the efficacy of this new tractionless cutting device in vitreoretinal surgery.

Adult↗
PubMed2005

Epiretinal pathology of diffuse diabetic macular edema associated with vitreomacular traction.

PURPOSE: To investigate the ultrastructure of the vitreomacular interface in patients with diffuse diabetic macular edema (DDME) associated with vitreomacular traction. DESIGN: Laboratory investigation. METHODS: Fifty-five consecutive patients with DDME underwent vitrectomy with en-bloc removal of the inner limiting membrane (ILM) and epimacular tissue. Six patients were operated on both eyes. Sixty-one specimens harvested during vitrectomy were analyzed by electron microscopy. RESULTS: Preoperatively, a thickened premacular cortical vitreous was present in 47 eyes. Native vitreous collagen with single cells interspersed within the collagenous layer or a cellular monolayer were the ultrastructural features in these eyes. Twenty-three eyes showed an epimacular membrane. In eyes with obvious signs of tangential vitreomacular traction, multilayered membranes situated on a layer of native vitreous collagen were found. Fibroblasts and fibrous astrocytes were the predominant cell types; myofibroblasts and macrophages were also present. Sixty of 61 specimens showed native vitreous collagen covering the ILM. Macular edema resolved in 58 eyes and persisted in 3 eyes. No recurrent fibrocellular proliferation was observed during the follow-up period of 18 months (mean, 3 to 56 months). CONCLUSIONS: The vitreomacular interface in eyes with DDME is characterized by a layer of native vitreous collagen and a varying cellular component. Tangential vitreomacular traction is associated with multilayered membranes situated on a layer of vitreous collagen. Resolution of macular edema does not depend on the presence and removal of contractile membranes. In eyes without tangential traction, complete removal of epimacular tissue also leads to fluid resorption.

Adult↗
PubMed2005

Staining and peeling of the internal limiting membrane in the cat eye.

PURPOSE: To investigate the cat vitreomacular interface using trypan blue (TB) and indocyanine green (ICG) and to determine the validity of the cat model in terms of staining and peeling of the internal limiting membrane (ILM). METHODS: Lensectomy and vitrectomy were performed in four eyes of two cats. The ILM of two eyes was stained with TB (0.15%). ILM peeling was performed in one eye. Two eyes were stained with ICG (0.5%). One eye was illuminated for 3 min. Light and transmission electron microscopy and confocal microscopy were performed. RESULTS: Clinically, both dyes stained the cat ILM similar to human ILM. TB staining resulted in a normal ultrastructure and antigenity of the retina. ILM peeling was associated with intraretinal bleeding. There were fragments of Müller cells adherent to the retinal side of the ILM, and Müller cell endfeet were ruptured and avulsed. ICG staining of the ILM followed by illumination caused severe inner retinal damage. ICG without illumination resulted in focal ILM detachments associated with tearing of Müller cell endfeet. CONCLUSIONS: The cat can be used as a model to study the effect of TB and ICG on the central area of the cat retina, as previous results from clinical and experimental postmortem settings in human eyes were confirmed in the current study. Peeling of the ILM as a sheet as performed in human macular surgery is not feasible. Differences in the ultrastructure of the ILM and a strong adhesion of the ILM to Müller cell endfeet may account for this observation.

Animals↗
PubMed2005

Histology of the vitreoretinal interface after indocyanine green staining of the ILM, with illumination using a halogen and xenon light source.

PURPOSE: To assess the histology of the retinal surface after staining of the inner limiting membrane (ILM) with indocyanine green (ICG) followed by illumination with halogen or xenon light sources in human donor and porcine eyes. METHODS: Ten eyes of six human donors and six porcine eyes were used in the study. In human donor eyes, the postmortem time varied between 7 and 38 hours, and porcine eyes were evaluated 9 hours after death. In all eyes, the vitreous was removed, and a few drops of 0.5% ICG were poured over the trephined posterior pole and carefully washed out after a period of 1 minute, with balanced salt solution. Then the stained retina was illuminated for 3 minutes with different light sources: a halogen light source of 145-W power or a xenon light source of 50-W power. Adjacent, unstained retina of each eye served as a control to assess postmortem artifacts. In two human and two porcine eyes ICG was applied without illumination. Retinal specimens were evaluated by light and electron microscopy. RESULTS: In human eyes, severe disorganization of the innermost retina and ILM loss were observed after ICG application with subsequent illumination with the halogen light source. After illumination with the xenon light source, there was only slight vacuolization of the innermost retina, with mostly intact Muller cells. The ILM remained in situ in relation to the retinal surface. Intact cellular architecture was found in all specimens after ICG staining without subsequent illumination and control specimens of unstained retina. In porcine eyes, no impact attributable to the light source or ICG alone was noted in this experimental setting. CONCLUSIONS: These findings suggest that adverse effects of ICG at the retinal surface may depend on the light source used during vitrectomy and correlate with the emission spectrum of the different light sources. In addition, care should be taken when comparing results obtained in human eyes and porcine eyes.

Adolescent↗
PubMed2004

Histology of the vitreoretinal interface after staining of the internal limiting membrane using glucose 5% diluted indocyanine and infracyanine green.

PURPOSE: To evaluate the effect of indocyanine green (ICG) diluted with glucose 5% on the human retina in an experimental setting in postmortem eyes and during surgery for macular hole formation. DESIGN: Histopathological evaluation. METHODS: Possible adverse effects of two different solutions of 0.05% ICG (Pulsion, Munich, Germany; and Infracyanine, Laboratoire SERB, Paris, France) diluted with glucose 5% were evaluated in four eyes of two donors. In one eye of each donor, the ICG-stained macula was illuminated with 380 to 760 nm using the light source of a commonly used vitrectomy machine. In the other eye, ICG was applied to the macula without illumination. The retinal specimens were evaluated using light- and electron microscopy. Additionally, the ultrastructure of the internal limiting membrane (ILM) of four eyes that underwent ICG-assisted vitrectomy for macular hole formation was examined. RESULTS: In the postmortem study, both solutions of ICG caused significant morphologic alterations of the inner retina after light exposure. There was disorganization of the inner retina and complete loss of ILM after application of the dye and illumination. In contrast, no abnormalities were found after application of the dye without illumination and in unstained control specimens. No differences were noted between the two ICG products. Specimens of the ILM harvested during vitrectomy revealed cellular elements adjacent to the retinal side of the ILM. CONCLUSIONS: Staining of the ILM using ICG diluted in glucose 5% followed by illumination might induce an adverse effect on the inner retina and may result in an alteration of the cleavage plane from the ILM to the innermost retinal layers.

Adult↗