Techniques for Processing Eyes Implanted with a Retinal Prosthesis for Localized Histopathological Analysis: Part 2 Epiretinal Implants with Retinal Tacks
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Date
2014-12
Journal Title
Journal ISSN
Volume Title
Publisher
JoVE Corp
Abstract
Retinal prostheses for the treatment of certain forms of blindness are gaining traction in clinical trials around the world with commercial
devices currently entering the market. In order to evaluate the safety of these devices, in preclinical studies, reliable techniques are needed.
However, the hard metal components utilised in some retinal implants are not compatible with traditional histological processes, particularly in
consideration for the delicate nature of the surrounding tissue. Here we describe techniques for assessing the health of the eye directly adjacent
to a retinal implant secured epiretinally with a metal tack.
Retinal prostheses feature electrode arrays in contact with eye tissue. The most commonly used location for implantation is the epiretinal location
(posterior chamber of the eye), where the implant is secured to the retina with a metal tack that penetrates all the layers of the eye. Previous
methods have not been able to assess the proximal ocular tissue with the tack in situ, due to the inability of traditional histological techniques to
cut metal objects. Consequently, it has been difficult to assess localized damage, if present, caused by tack insertion.
Therefore, we developed a technique for visualizing the tissue around a retinal tack and implant. We have modified an established technique,
used for processing and visualizing hard bony tissue around a cochlear implant, for the soft delicate tissues of the eye. We orientated and
embedded the fixed eye tissue, including the implant and retinal tack, in epoxy resin, to stabilise and protect the structure of the sample.
Embedded samples were then ground, polished, stained, and imaged under various magnifications at incremental depths through the sample.
This technique allowed the reliable assessment of eye tissue integrity and cytoarchitecture adjacent to the metal tack.
Description
Keywords
Retinal Prosthesis, Implant, Epiretinal, Histology, Fixation, Tack, Grinding, In Situ
Citation
Nayagam, D. A. X., Durmo, I., McGowan, C., Williams, R. A. & Shepherd, R. K. (2014). Techniques for Processing Eyes Implanted With a Retinal Prosthesis for Localized Histopathological Analysis: Part 2 Epiretinal Implants with Retinal Tacks. Journal of Visualized Experiments, e52348.