A 4.49nW/Pixel Light-to-Stimulus Duration Converter-Based Retinal Prosthesis Chip.

This paper presents a 288-pixel retinal prosthesis (RP) chip implemented in a 0.18 µm CMOS process. The proposed light-to-stimulus duration converter (LSDC) and biphasic stimulator generate a wide range of retinal stimuli proportional to the incident light intensity at a low supply voltage of 1V. The implemented chip shows 25.5 dB dynamic stimulation range and the state-of-the art low power consumption of 4.49 nW/pixel. Ex-vivo experiments were performed with a mouse retina and patch-clamp recording. The electrical artifact recorded by the patch electrode demonstrates that the proposed chip can generate electrical stimuli that have different pulse durations depending on the light intensity. Correspondingly, the spike counts in a retinal ganglion cell (RGC) were successfully modulated by the brightness of the light stimuli.

Patient-performed seton irrigation for the treatment of deep horseshoe fistula.

PURPOSE: Compared with total fistulotomy using a lay-open technique for treatment of deep horseshoe or deep posterior complex anal fistula, the seton drainage method has reduced damage of the external anal sphincter. However, conventional seton drainage is burdensome to patients, requiring frequent clinic visits for wound management during prolonged periods while the drainage tube is in place. To reduce the number of clinic visits and facilitate healing, we devised a patient-performed seton irrigation technique and compared the results with a conventional loose seton to determine its clinical usefulness. METHODS: We reviewed medical records of 24 patients who were diagnosed with deep horseshoe fistula and underwent surgery between January 1999 and December 2004. Twelve patients treated through December 2001 received a conventional loose seton. Twelve patients treated from January 2002 performed self-irrigation via the seton. These 2 groups were compared regarding duration of purulent discharge, length of time until seton removal, and recurrence rate. RESULTS: The mean duration of purulent discharge was 18.75 (range, 15-24) days for self-irrigation vs 29.75 (24-37) days for conventional loose seton treatment (P < .001). The mean time to removal of the seton was 21.58 (18-29) days for self-irrigation vs 32.58 (28-39) days for conventional treatment (P < .001). The recurrence rate after surgery was 8.3% for self-irrigation vs 16.7% for conventional treatment (P > .99). CONCLUSION: Patient-performed seton irrigation shortens the period of treatment and healing through more effective wound management, and we propose this technique as a useful new method of treating deep horseshoe fistula.