Histopathology Findings following Retinal Tack Implantation (With 1 color plate)

Daus, W.; Völcker, H. E.; Alexandridis, E.; Käsmann, B

doi:10.1159/000310035

Cited by 5 publications

(6 citation statements)

References 6 publications

(5 reference statements)

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“…Any impact of the tack on local circulatory structures appeared minimal and was clinically insignificant to these subjects with severe retinal degeneration. The appearance of the tack extraction site in all four cases was similar to earlier published interpretations of healing response around retinal tacks in human subjects, which involved localized fibrovascular tissue proliferation [12] and moderate gliosis [13]. …”

Section: Discussionsupporting

confidence: 83%

Extraction of retinal tacks from subjects implanted with an epiretinal visual prosthesis

Juan

Spencer

Barale

et al. 2013

Graefes Arch Clin Exp Ophthalmol

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Background Retinal tacks, first developed for the treatment of complex retinal detachments, have more recently been used for the fixation of epiretinal electrode arrays as part of implanted visual prostheses. Here we report on the clinical experience of extracting four such tacks after chronic implantation. The ability to safely extract retinal tacks ensures that epiretinal devices can be repositioned or removed if necessary. Methods Custom-built, titanium alloy retinal tacks were mechanically removed from the posterior coats after prolonged implantation (up to 19 months). The resulting wound was characterized by clinical evaluation, fundus photography and fluorescein angiography while being monitored for stability over time. The wounds were also compared to earlier published reports of the healing response around retinal tacks in human subjects. Results Tack extraction was accomplished successfully, without complication, in all four subjects. The wound site was readily identified by pale scar tissue. No change in the wound size or appearance was noted over many months of post-operative observation (up to 22 months after explant). No adverse effects on overall ocular health were detected. Conclusion Extraction of retinal tacks from subjects implanted with epiretinal prostheses can be performed without significant complication. The long-term healing response appears to be stable and localized in eyes afflicted with retinitis pigmentosa or choroideremia. There was also minimal, if any, impact on the local circulatory system. These cases suggest that the use of retinal tacks for anchoring epiretinal visual prostheses does not preclude safe repositioning or removal of the device more than a year after implant.

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Section: Discussionsupporting

confidence: 83%

Extraction of retinal tacks from subjects implanted with an epiretinal visual prosthesis

Juan

Spencer

Barale

et al. 2013

Graefes Arch Clin Exp Ophthalmol

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“…A moderate gliosis as well as minor residua of blood are known to be found in the surroundings of retinal tacks [24][25][26][27] . The gliosis is not per se regarded to be a threat to the retinal tissue.…”

Section: Discussionmentioning

confidence: 99%

Surgical Results and Microscopic Analysis of the Tissue Reaction following Implantation and Explantation of an Intraocular Implant for Epiretinal Stimulation in Minipigs

et al. 2011

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Aims: For the purpose of visual rehabilitation of subjects with photoreceptor degeneration, an implantable microelectronic device for epiretinal stimulation was developed. Our study aimed to show whether implantation and explantation could be conducted safely and to investigate tissue compatibility. Methods: The device was implanted in 5 Göttinger minipigs. Four weeks later, the implant was surgical- ly removed. Histopathological examination that followed aimed at detecting inflammatory or proliferative changes. Stains used were hematoxylin and eosin, leukocyte common antigen, CD68 and glial fibrillary acidic protein. A grinding technique was used to visualize the retinal tissue in conjunction with the retinal tacks. Results: The implantation of the devices was successful in all cases. The explantation was complicated by intraoperative hemorrhages. Complete explantation could only be achieved after modifying the implantation strategy. Histopathology revealed a mild degree of cystic disaggregation of the retina. Immunohistochemically, an increased glial fibrillary acidic protein expression of Müller cells was found, which shows a moderate glial cell activation. Inflammatory cells were absent. Using the grinding technique, tissue adjacent to the retinal tacks showed a mild gliosis. Discussion: The viability of implantation and explantation of the implant in minipigs has been shown. The absence of immunoreactive cells or a considerable glial reaction suggest that the device may be considered safe and suitable for further implantation in humans.

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“…Histopathological analysis performed on eyes of two unfavourable cases with total retinal detachment (Daus et al 1989, Nork et al 1990) do not contribute additional information regarding this problem apart from the impression that tacks did not seem to be inductive on the ongoing proliferative vitreoretinopathy but the tissue capsule around tacks may have acted as anchor to contractile proliferative membranes or strands (Nork et al 1990). Whether tacks used in these cases had an effect, positive or negative, on the ongoing proliferative disease and, vice versa, if proliferative vitreo-retinopathy did influence tissue reactions towards implantated tacks, remains open.…”

Section: Discussionmentioning

confidence: 99%

Successful long-term evaluation of intraocular titanium tacks for the mechanical stabilization of posterior segment ocular implants

Gerding

Taneri

Benner

et al. 2001

Mat.-wiss. u. Werkstofftech.

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Presently there are several lines of new intraocular implants under development (retina stimulators, drug delivery systems and others) that necessitate novel anchoring techniques for the posterior eye segment. It was the aim of this study to test intrasclerally inserted titanium tacks for this purpose in rabbit eyes under long‐term observation. Insertion of titanium tacks was performed through vitreous cavity and retina into the sclera in six rabbits after vitreous removal by mechanical and enzyme assisted (plasmin) vitrectomy. Follow‐up (between 2 weeks and 6 months, median: 4.5 months) and outcome were analyzed using fundus imaging, echography, electroretinography, light microscopy (standard, immunhistochemistry), and scanning electron microscopy. Intraoperative handling of tacks (Heimann design) revealed as a critical manouver due to relatively high mechanical force necessary for insertion. Position of tacks was stable without any signs of extrusion, tilting or dislocation in all eyes during the whole follow‐up period. Tack surface in contact with ocular tissue was embedded by a thin capsule of fibroglial avascular tissue extending from choroid and retina. Scanning electron microscopy of explanted tacks did not present any sign of surface degradation. The retina around inserted tacks presented a regional fibroglial transformation and thickening limited to the surround of insertion (radial diameter < 750 μm). No significant signs of proliferative disease or retinal degeneration were detected outside this area by funduscopy, histology, or in electroretinography. In one case the retina detached due to intraoperative complications not related to the insertion. Results of this study demonstrate that intrascleral tacks provide principially a permanent, stable, and biocompatible option for posterior segment anchoring necessary for the mechanical stabilization of intraocular implants. It is desired to design mimimalized structures in order to limit the surgical trauma of tack insertion.

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Histopathology Findings following Retinal Tack Implantation (With 1 color plate)

Cited by 5 publications

References 6 publications

Extraction of retinal tacks from subjects implanted with an epiretinal visual prosthesis

Extraction of retinal tacks from subjects implanted with an epiretinal visual prosthesis

Surgical Results and Microscopic Analysis of the Tissue Reaction following Implantation and Explantation of an Intraocular Implant for Epiretinal Stimulation in Minipigs

Successful long-term evaluation of intraocular titanium tacks for the mechanical stabilization of posterior segment ocular implants

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