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Visual outcome in 29 blind retinitis pigmentosa patients with electronic subretinal implant Alpha-IMS

Session Details

Session Title: Vitreo Retinal Surgery I

Session Date/Time: Thursday 11/09/2014 | 08:00-10:00

Paper Time: 08:00

Venue: Auditorium

First Author: : E.Zrenner GERMANY

Co Author(s): :    K.U. Bartz-Schmidt   F. Gekeler   T.L Jackson   R. McLaren   S. Katarina   a. Study Group

Abstract Details

Purpose:

To assess the 12-month visual and safety outcomes following implantation of a 1500-pixel subretinal implant in patients blind from retinitis pigmentosa (RP).

Setting:

A prospective mono-& multicenter clinical trial on safety & efficacy of subretinal implants for partial restoration of vision in patients blind from hereditary retinal dystrophies; multicenter phase interim report. http://www.clinicaltrials.gov Registration number: NCT00515814, NCT01024803, NCT01497379

Methods:

Alpha IMS subretinal implants (Retina Implant AG, Reutlingen, Germany) were positioned beneath the foveal region of 16 male and 13 female RP-patients (mean age 53.8 ± 8.2). Each of the 1500 subfoveal photodiodes within an 11° by 11° field controls an amplifier that, depending on the strength of the light, emits currents to stimulate overlying bipolar cells. Power and control signals are supplied inductively via a subdermal, retroauricular coil from which a subdermal cable leads to the eyeball. Function was tested by 4 procedures - 1: Monitor-based standardized tests for light perception, light localization, movement detection, grating acuity and visual acuity with Landolt C-rings (2- or 4 alternative-force-choice-tests); 2: Detection, localization and identification of objects placed on a table; 3: Reading letters; 4: Visual experiences during outdoor and daily-life activities.

Results:

1: Implant-mediated light perception was possible for 25 (86%) patients; light localization for 17 (59%); movement detection (up to 35 cycles/degree) for 6 (20%); measurable grating acuity (up to 3.3 cycles/degree) for 14 (48%) and measurable visual acuity (up to 20/546) for 4 patients (14%). 2: On a visual ability scale from 0 (worst) to 4 (best) for 4 white geometric figures presented on a black table, patients averaged 2.7 ± 0.3 for detection, 2.5 ± 0.2 for localization and 1.0 ± 0.04 for identification at month 1 which was significantly better than with chip power switched off. Similar results were obtained with a table setup of activities of daily living. Detection, localization and recognition of shapes and objects in an activities of daily living task was significantly better with implant power switched on than off during the first three months (p<0.05). 3: Four patients (14%) could read letters 4-8 cm in size. 4: Thirteen patients (45%) reported useful visual experiences including recognition of shapes or details in daily life and 8 patients (28%) could localize objects in daily life without details. 5: Besides two treatable serious adverse events there were no safety concerns.

Conclusions:

The Alpha-MS implant has a CE mark for commercial use in Europe. Psychophysical testing and self-reported outcomes show restoration of useful vision in a majority of patients. Subretinal implantation surgery is safe and a multicenter study is continuing.

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