Nidek (Japan)

This demonstration embodies a prototyping device for artificial vision systems. This device consists of goggles and a smartphone, equipped with an application that replicates light perception in real time by converting images sourced from the smartphone's internal camera. This instrument enables a person with vision to gain insights into how users of the artificial vision device would perceive and recognize their environment through the artificial vision systems.

Purpose Retinal vessels reflect alterations related to hypertension and arteriosclerosis in the physical status. Previously, we had reported a deep-learning algorithm for automatically detecting retinal vessels and measuring the total retinal vascular area in fundus photographs (VAFP). Herein, we investigated the relationship between VAFP and brachial–ankle pulse wave velocity (baPWV), which is the gold standard for arterial stiffness assessment in clinical practice. Methods Retinal photographs (n = 696) obtained from 372 individuals who visited the Keijinkai Maruyama Clinic for regular health checkups were used to analyze VAFP. Additionally, the baPWV was measured for each patient. Automatic retinal-vessel segmentation was performed using our deep-learning algorithm, and the total arteriolar area (AA) and total venular area (VA) were measured. Correlations between baPWV and several parameters, including AA and VA, were assessed. Results The baPWV was negatively correlated with AA (R = –0.40, n = 696, P < 2.2e-16) and VA (R = –0.36, n = 696, P < 2.2e-16). Independent variables (AA, sex, age, and systolic blood pressure) selected using the stepwise method showed a significant correlation with baPWV. The estimated baPWV, calculated using a regression equation with variables including AA, showed a better correlation with the measured baPWV (R = 0.70, n = 696, P < 2.2e-16) than the estimated value without AA (R = 0.68, n = 696, P < 2.2e-16). Conclusions AA and VA were significantly correlated with baPWV. Moreover, baPWV estimated using AA correlated well with the actual baPWV. VAFP may serve as an alternative biomarker for evaluating systemic arterial stiffness.

Abstract This study proposes an alternating current (AC)‐driven retinal prosthesis device using an implantable CMOS‐LSI chip that can control multiple electrodes. The proposed device uses AC power with the electrical grounds of the main and stimulation units separated to reduce the possibility of current leakage and to improve safety. The stimulation unit implanted in the eye cannot include large capacitor chips for ground separation. To solve this problem, large capacitor chips are mounted on the implantable control unit that supplies power, not on the stimulating device, and a cooperative mode of operation is devised. In this way, it is realised that a circuit configuration that achieves both miniaturisation and improved power supply efficiency. This study verifies the functionality of the proposed circuit. The results suggest that power supply and stimulation operations are possible through coupling capacitors. In addition, this stimulation operation can be performed continuously.

We have been developing a retinal prosthesis based on suprachoroidal transretinal stimulation (STS). From a practical viewpoint, it is essential to confirm the safety and effectiveness of continuous electrical stimulation to the retina. In this study, the electrical stimulation of a rabbit retina for 8 h a day was conducted for one month, and its safety and efficacy were evaluated by histological, electrophysiological, and electrochemical methods. Results suggested that one month of semichronic electrical stimulation by STS was safe and effective.

Development of direct neural interface (DNI) including visual prostheses absolutely requires confirmation of their long-term safety and stability. Functional evaluation by electrically evoked potentials (EEPs) is effective in this regard, although the recording system must be stable for chronic use. In addition, control of anesthetic depth is important for stable recording of the evoked potentials. The purpose of this study was to develop a chronically implanted electrode capable of recording visual evoked responses safely during repeated anesthesia over long periods, which would allow more effective safety evaluations of not only visual prostheses but also DNI. We developed two types of electrodes, and implanted them into rabbits. A general screw electrode was used for comparison with the novel electrodes. Structurally, the newly developed platinum (Pt) ball-tip screw electrode consisted of a plastic screw with smoothly surfaced Pt balls on the tip. The depth of implantation into the brain was adjustable via a threaded insert installed in the skull. The newly developed platinum/iridium (Pt/Ir) ball-tip planar multi-electrode array (MEA) comprised Pt/Ir ball electrodes placed in a two-dimensional lattice pattern, which was implanted just beneath the skull. These electrodes recorded variations in visual evoked potentials (VEPs) in response to 20 J flash stimuli over a period of 48 weeks. After 48 weeks of implantation, the ability of the electrodes to continue recording EEPs was confirmed (500 µA, 500 µs, cathodic first biphasic). During the recording of VEPs and EEPs, stable anesthesia was maintained with isoflurane (end-tidal 2.4%). The depth of anesthesia using isoflurane could be adjusted safely, and allowed stable recording of evoked potentials throughout the long-term study. However, stable recording using the general screw electrode was possible only for a short period. We also obtained stable latency and N1 amplitude readings over the 48 weeks using the newly developed electrodes, and successfully recorded EEPs after the 48-week period. These results suggest that the novel electrodes work well over the entire duration of the study, and may allow assessment of long-term safety and stability of not only visual prostheses, but also other devices utilizing brain machine interfaces or direct neural interfaces.

To assess photoreceptor structure in macular microholes by using adaptive optics scanning laser ophthalmoscopy (AO-SLO) and spectral-domain optical coherence tomography (SD-OCT) and compare with visual acuity. Fourteen eyes from 12 patients with macular microholes underwent a full ophthalmologic examination and imaging with a fundus camera, SD-OCT, and an original prototype AO-SLO system at each visit. All eyes had a cone outer segment tip line disruption and a normal retinal pigment epithelium line on SD-OCT images. Adaptive optics scanning laser ophthalmoscopy revealed foveal cone disruption (13 eyes, round or oval; 1 eye, T-shaped) in all eyes. Cone disruption area (mean = 14,805 ± 9120 μm(2); range, 3495-35,901 μm(2)) positively correlated with logMAR visual acuity at the first visit (P = 0.015, rs = 0.679). During the follow-up period, cone disruption area increased in two eyes, was stable in seven eyes, and decreased in five eyes. At the last visit, cone disruption area (mean = 8717 ± 7432 μm(2); range, 0-25,746 μm(2)) also positively correlated with logMAR visual acuity (P = 0.035, rs = 0.610). In one patient with bilateral microholes and no apparent vitreous traction, lesion size gradually increased. Cone disruption area decreased and visual acuity improved following oral prednisone therapy. Cone disruption occurs in eyes with macular microholes and a larger cone disruption area translates into a poorer visual acuity. Macular microholes, which are commonly observed as foveal cone inner and outer segment disruptions, may occur in eyes with or without vitreofoveal traction.