Abstract
Purpose:
Active subretinal visual prostheses require a transchoroidal implantation. The reason fot that is the necessity of an external energy supply. Surgically the choroidal access was assumed to be one of the major problems.
Methods:
26 legally blind RP patients were included in the multicentre study to regain vision with electronic chips. Patients were implanted with a chronic active prosthetic subretinal device via a transchoroidal surgical access. A subgroup of 12 out of these 26 patients were operated by one surgeon who had developed the transchoroidal procedure and had experience with it. Only this subgroup was analyzed to eliminate the learning curve effects of multiple surgeons and to estimate the frequency and the outcome after occurence of choroidal promlems.
Results:
All implantations were carried out successfully and led to a stable retinal situation. Feared major bleedings were no observed. Accidental perforation of the choroid occurred (1) in the area of the posterior pole. Problems were observed when advancing the guide foil or the implant subretinally due to adhesions between RPE and retina. Adhesions seem to be common in the area of dense pigmentation or scaring in RP patients. Sub RPE implantation occurred twice but could be corrected within the same surgical session. This never was associated with bleedings or other unexpected effects.
Conclusions:
Problems resulting from the choroid occur but are are manageable and seem not to be a limiting factor for this procedure. Perforations of the choroid that occurred did not have a threatening or harmful decisive side effect. Proper guide foil and implant design are relevant. Design of this tools are under improvement to minimize incidents resulting from this challenge. Difficult retinal situations are no contraindication for chip implantation.