gms | German Medical Science

Background: To evaluate the improvement of reaching movement in a patient implanted with retinal prosthesis by suprachoroidal-transretinal stimulation (STS).

Methods: The subject was a 42-year-old man with advanced Stargardt disease with visual acuity of LP (right eye) and HM (left eye). We implanted STS retinal prosthesis in the right eye after the approval of the Institutional Review Board of Osaka University Medical School. In the localization test, a target of white square (visual angle; 10°) was displayed on the PC monitor at a random position and subjects were instructed to touch the center of a target (n=20). We measured the distance between the touched point and the center of a target and averaged (average deviation) in a condition with system ON and OFF.

Results: When the left eye was occluded, the average deviation with system ON was not different from that with system OFF for a high contrast target (96%) but was smaller with system ON than system OFF for a low contrast target (85%) (system, ON; 7.6±4.3°, OFF; 17.2±9.6°, P<0.001). With system ON and with a low contrast target, the average deviation was also smaller with the right-eye occlusion and the both-eye open condition. With the system ON, the average touching time was shorter with right-eye occlusion and both-eye open than with left-eye occlusion (right-eye occlusion; 2.41 sec, both-eye open; 2.23 sec, left-eye occlusion; 8.45 sec, P<0.001 one way ANOVA).

Conclusion: With the appropriate target contrast, the accuracy of reaching movement improved in a patient with retinal prosthesis. A possibility exists that patients with retinal prosthesis can improve their visual performance using both the prosthetic vision and the residual natural vision.

Acknowledgment: This work was supported by the Translational Research Network Program (B03) from the Ministry of Education, Culture, Sports, Science and Technology, Japan.