iris pilot - extended pilot study with a retinal implant system

Conditions: Retinitis Pigmentosa; Cone-Rod Dystrophy; Choroideremia

Summary: investigate whether blind subjects that fulfil the patient criteria provided with a retinal implant are able to differentiate between simple patterns like horizontal bar, vertical bar and cross.

the retinal implant system consists of three main components, the retinal stimulator, which is the component actually implanted into the eye, the visual interface, and the pocket processor the retinal stimulator will be implanted into the eye of a blind subject during a surgical operation. however, the external components are activated only during the test sessions under the control of the investigator team. in a first step of the investigation a software controlled system on a pc which is connected to the pocket processor via ethernet interface, will generate the defined stimulation patterns (bars, crosses, cubes). during the test session, the blind subject is exposed to a series of these stimulation patterns and he / she has to describe the visual perceptions. based on his descriptions and in an interactive way, the stimulation signal is subsequently be modulated by changing parameters like amplitude, duration of impulse, polarity, number of repetitions or pulse frequency on the pc. in a second step the visual interface is equipped with a camera which presents realtime images to the subject. data obtained from the investigation with computer generated patterns in the first step are used in the second step to improve the fitting software for the use in the camera supported system. finally the system should enable the subject to recognize simple images supported from the camera.

Eligibility criteria:
inclusion criteria * age between 30 and 79 years at the date of enrollment * normal hearing and linguistic understanding (with hearing aids if - necessary and in the language of the hospital or in english) * ability to understand the study and procedures involved * willingness to participate and comply with follow-up procedures * good general health based on investigator's opinion * ability to undergo surgery using general anaesthesia * signed informed consent * rp, choroideremia, or rod cone dystrophy * visual field less than 40 ° (if measurable) * visual acuity not better than (1/50), (logmar≥1.7) * visual function stable for a duration of at least one year (according to subject statement) * normal eye pressure (9-21 mmhg) * bulbus length (ap) between 21 and 25 mm exclusion criteria * allergic response to multiple antibiotics * known allergies to materials of the implant * known carrier of multi-resistant organisms * pregnancy or lactating * history of epileptic seizures * having active implantable devices (or need within the next 3 years) * patients with cancer or patients received cancer therapy within the last 2 years * currently undergoing psychiatric treatment without expert opinion approving participation on the study * patients having insufficient mental capacity * neurological diseases, in particular those affecting nerve conduction velocities * patients currently taking medications affecting brain function * immunosuppressive subjects

Keywords: visual perception retina light retinitis pigmentosa visual acuity retinal implant electrical stimulation