Abstract
Abstract: :
Purpose:Legal requirements for human implants as well as ethic considerations make the removal or exchangeability of an implant desirable. The possibility of a future implantation of a further developed device id decisive for the collective of patients which is supplied with implants in the first phase. Methods:5 Cats previously implanted with micro photo diode arrays (MPDA) received a second vitrectomy were the implanted device was exchanged. To access the fist implant balanced salt solution (BSS) was injected adjacent to the chip leading to a little bleb in the subretinal space. To minimize trauma to the retina a viscoelastic substance is injected into the subretinal bleb. Through a 2 mm retinotomy the implant can easily be accessed and removed with a forceps. In a further step a second implant is inserted via the same retinotomy. Results:The feasibility of an implant exchange could be demonstrated in the cat model. All 5 implant exchanges in cats showed no complication in postoperative follow up. The re-implanted device remained stable in its position. The reattached retina showed no difference after the second implantation compared with the first one. Conclusion:The demonstration of feasibility of an implant exchange opens a variety of possibilities for future implantation procedures. Specific legal considerations of implant surgery are therefore taken into account.
Keywords: 316 animal model • 559 retinal connections, networks, circuitry