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Explantation of Tack-fixated EPIRETINAL Microcontact Foils in Rabbits - Preliminary Observations
1Berk H., 1Vobig M. A., 1Marzella G., 2Held S., 1Alteheld N., 1Walter P.,
1Universität zu Köln, Zentrum für Augenheilkunde (Köln)
Purpose: To determine if explantation of epiretinally implanted and tack fixated microcontact foils as a part of a retinal prosthesis is feasible in rabbits.
Methods: After vitrectomy microcontact foils were fixated onto the visual streak by a retinal tack in six rabbits. With an interval between 4 to 12 weeks later the implants and the tack were explanted. Explantation consisted of epiretinal membrane peeling, tack mobilization, retinotomy, tack and implant removal, PFCL, endolaser, and tamponade with silicone oil or air. During a follow-up of three months the animals were examined by means of ERG, VEP, and ophthalmoscopy.
Results: Implantation and tack fiation was successful in 5/6 cases. In one case a total retinal detachment was observed due to PVR. The explant procedure will be demonstrated. Although extensive vitreoretinal manipulations were necessary to remove the implant, the procedure seemed to be feasible and comparable to the removal of intraretinal foreign bodies. In four cases the eye was filled with silicone oil, in one case we used air due to a very limited retinal trauma. In two cases we observed a total retinal detachment due to PVR after explantation due to large retinal defects. In the other three eyes the retina remained attached. In this series of experiments it was not possible to preserve the retinal area under the microcontacts due to the strong adherence between the implant and the retinal surface, which could also be demonstrated by REM studies of the explant.
Conclusions: Explantation of tack fixated microcontact foils seemed surgically to be feasible. The functional and anatomical outcome was strongly associated with the size of the retinal defect induced by the explantation procedure.