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[IEEE 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Honolulu, HI, USA (2018.7.18-2018.7.21)] 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Automatic Detection of Preferred Retinal Locus (PRL) for Low Vision Rehabilitation using Oculometrics Analysis*
摘要： Low vision rehabilitation is an important step towards individuals with Age-related macular degeneration (AMD) regaining useful functional vision and quality of life. One of the key steps in low vision rehabilitation is the determination of the preferred retinal locus (PRL). Currently, localization of PRL is performed manually though the guidance of a low vision therapist and the process is highly time-consuming, labour-intensive and subjective. In this paper, we present an automated system to objectively and accurately locate an individual’s PRL with the aid of gaze tracking technology. We also propose a graph-based method for false fixation detection to improve the system robustness. We validated the reliability of the system by using eye tracking technology to simulate central vision loss on people with normal vision. Experimental results show the potential use of eye tracking in detecting PRL for low vision rehabilitation.
关键词： Preferred retinal locus,Eye tracking technology,Low vision rehabilitation,False fixation detection,Age-related macular degeneration
更新于2025-09-10 09:29:36
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The Pattern of Visual Fixation Eccentricity and Instability in Optic Neuropathy and Its Spatial Relationship to Retinal Ganglion Cell Layer Thickness
摘要： The purpose of this study was to assess whether clinically useful measures of fixation instability and eccentricity can be derived from retinal tracking data obtained during optical coherence tomography (OCT) in patients with optic neuropathy (ON) and to develop a method for relating fixation to the retinal ganglion cell complex (GCC) thickness. Twenty-nine patients with ON underwent macular volume OCT with 30 seconds of confocal scanning laser ophthalmoscope (cSLO)-based eye tracking during fixation. Kernel density estimation quantified fixation instability and fixation eccentricity from the distribution of fixation points on the retina. Preferred ganglion cell layer loci (PGCL) and their relationship to the GCC thickness map were derived, accounting for radial displacement of retinal ganglion cell soma from their corresponding cones. Fixation instability was increased in ON eyes (0.21 deg2) compared with normal eyes (0.06982 deg2; P < 0.001), and fixation eccentricity was increased in ON eyes (0.488) compared with normal eyes (0.248; P ? 0.03). Fixation instability and eccentricity each correlated moderately with logMAR acuity and were highly predictive of central visual field loss. Twenty-six of 35 ON eyes had PGCL skewed toward local maxima of the GCC thickness map. Patients with bilateral dense central scotomas had PGCL in homonymous retinal locations with respect to the fovea. Fixation instability and eccentricity measures obtained during cSLO-OCT assess the function of perifoveal retinal elements and predict central visual field loss in patients with ON. A model relating fixation to the GCC thickness map offers a method to assess the structure–function relationship between fixation and areas of preserved GCC in patients with ON.
关键词： optic neuropathy,fixation,ganglion cell,OCT
更新于2025-09-10 09:29:36
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Variability in monocular and binocular fixation during standard automated perimetry
摘要： The aim of this cross-sectional study was to use standard automated perimetry to compare fixation variability among the dominant eye fixation, non-dominant eye fixation, and binocular fixation conditions. Thirty-five eyes of 35 healthy young participants underwent standard automated perimetry (Humphrey 24–2 SITA-Standard) in dominant eye fixation, non-dominant eye fixation, and binocular fixation conditions. Fixation variability during foveal threshold and visual field measurement, which was recorded using a wearable eye-tracking glass and calculated using the bivariate contour ellipse area (deg2), was compared among the three fixation conditions. Further, the association of bivariate contour ellipse area with ocular position and fusional amplitude during binocular fixation was analysed. There were no significant differences in bivariate contour ellipse area during foveal threshold measurement among the dominant eye fixation (1.75 deg2), non-dominant eye fixation (1.45 deg2), and binocular fixation (1.62 deg2) conditions. In contrast, the bivariate contour ellipse area during visual field measurement in binocular fixation (2.85 deg2) was significantly lower than the bivariate contour ellipse area in dominant eye fixation (4.62 deg2; p = 0.0227) and non-dominant eye fixation (5.24 deg2; p = 0.0006) conditions. There was no significant difference in bivariate contour ellipse area during visual field measurement between dominant eye fixation and non-dominant eye fixation conditions. There was no significant correlation between bivariate contour ellipse area and either ocular position or fusional amplitude during both foveal threshold and visual field measurements. Thus, fixation variability might be improved in binocular fixation conditions during a long-duration test, such as visual field measurement.
关键词： binocular fixation,standard automated perimetry,monocular fixation,fixation variability,bivariate contour ellipse area
更新于2025-09-09 09:28:46
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Clinical outcomes of 4-point scleral fixated 1-piece hydrophobic acrylic equiconvex intraocular lens using polytetrafluoroethylene suture
摘要： Purpose: To report the visual outcomes and complications of scleral fixated intraocular lenses (IOLs) using Gore-Tex suture. Methods: The current study is a retrospective noncomparative case series including patients who underwent scleral fixation of IOL (Akreos AO60) using Gore-Tex suture from August 2015 to March 2017 at a university teaching center. Primary outcome measures were visual acuity and complications at last follow-up. Results: The current study included 49 eyes of 48 patients. Mean follow-up duration postsurgery was 6.9 months (range: 0.9–29.4 months). The indications for secondary IOL surgery were dislocated IOL in 16/49 (33%), subluxed IOL in 9/49 (18%), dislocated or subluxed crystalline lens in 9/49 (18%), traumatic cataract in 8/49 (16%), and complicated cataract surgery in 7/49 (14%). Mean best-corrected logMAR visual acuity improved from 1±0.7 (20/200 Snellen equivalent) preoperatively to 0.5±0.5 (20/63 Snellen equivalent) at last follow-up. There were no intraoperative complications noted. Early postoperative complications included significant persistent corneal edema (longer than 1 week) in 4/49 (8.2%), ocular hypertension (intraocular pressure $25 mmHg) in 8/49 (16.3%), hypotony (intraocular pressure #5 mmHg) in 6/49 (12.2%), cystoid macular edema 3/21 (6.1%), IOL tilt 2/49 (4.1%), hyphema in 2/49 (4.1%), and vitreous hemorrhage in 5/49 (4.8%). There was one case of recurrent retinal detachment. One patient presented with an erosion of the Gore-Tex suture through the conjunctiva resulting in a purulent scleritis 6 months after the initial surgery, and was managed with removal of the IOL, debridement, and cryotherapy. Forty-one of 49 patients completed 3-month follow-up, among which visual acuity improved, deteriorated, or remained same compared to baseline in 27/49 (55.1%), 8/49 (16.3%), and 6/49 (12.2%) eyes, respectively. Conclusion: In the current study, visual acuity outcomes were generally favorable. The complications were largely transient. Significant complications included a suture-related infection, which required removal of the IOL, and a recurrence of a retinal detachment.
关键词： secondary intraocular lens,scleral fixation,clinical outcomes,Gore-Tex
更新于2025-09-09 09:28:46
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Metal-Ligand Cooperative Synthesis of Benzonitrile via Electrochemical Reduction and Photolytic Splitting of Dinitrogen
摘要： Thermal nitrogen fixation relies on strong reductants to overcome the extraordinarily large N–N bond energy. Photochemical strategies that drive N2 fixation are scarcely developed. Here, the synthesis of a dinuclear N2-bridged complex is presented upon reduction of a rhenium(III) pincer platform. Photochemical splitting into terminal nitride complexes is triggered by visible light. Clean N-transfer with benzoyl chloride to free benzamide and benzonitrile is enabled by cooperative 2H+/2e– transfer of the pincer ligand. A three-step cycle is demonstrated for N2 to nitrile fixation that relies on electrochemical reduction, photochemical N2-splitting and thermal N-transfer.
关键词： Rhenium,Photochemistry,Electrochemistry,Nitrogen Fixation,Pincer Ligand
更新于2025-09-09 09:28:46
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A Novel Green Stabilization of TiO2 Nanoparticles onto Cotton
摘要： Facile embedding of TiO2 nanoparticles onto cotton fabric has been successfully attained by ultraviolet light irradiations. The adhesion of nanoparticles with fibre surface, tensile behaviour and physicochemical changes before and after ultraviolet treatment were investigated by scanning electron microscopy, energy dispersive X-ray and inductive couple plasma-atomic emission spectroscopy. Experimental variables i.e. dosage of TiO2 nanoparticles, temperature of the system and time of ultraviolet irradiations were optimised by central composite design and response surface methodology. Moreover, two different mathematical models were developed for incorporated TiO2 onto cotton and tensile strength of cotton after ultraviolet treatment and used further to testify the obtained results. Self-clean fabric through a synergistic combination of cotton with highly photo active TiO2 nanoparticles was produced. Stability against ultraviolet irradiations and self-cleaning properties of the produced fabric were evaluated.
关键词： Nanoparticles,Self-stabilization,Self-cleaning,TiO2,UV fixation
更新于2025-09-09 09:28:46
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Binocular contrast discrimination needs monocular multiplicative noise
摘要： The effects of signal and noise on contrast discrimination are difficult to separate because of a singularity in the signal-detection-theory model of two-alternative forced-choice contrast discrimination (Katkov, Tsodyks, & Sagi, 2006). In this article, we show that it is possible to eliminate the singularity by combining that model with a binocular combination model to fit monocular, dichoptic, and binocular contrast discrimination. We performed three experiments using identical stimuli to measure the perceived phase, perceived contrast, and contrast discrimination of a cyclopean sine wave. In the absence of a fixation point, we found a binocular advantage in contrast discrimination both at low contrasts (<4%), consistent with previous studies, and at high contrasts (>34%), which has not been previously reported. However, control experiments showed no binocular advantage at high contrasts in the presence of a fixation point or for observers without accommodation. We evaluated two putative contrast-discrimination mechanisms: a nonlinear contrast transducer and multiplicative noise (MN). A binocular combination model (the DSKL model; Ding, Klein, & Levi, 2013b) was first fitted to both the perceived-phase and the perceived-contrast data sets, then combined with either the nonlinear contrast transducer or the MN mechanism to fit the contrast-discrimination data. We found that the best model combined the DSKL model with early MN. Model simulations showed that, after going through interocular suppression, the uncorrelated noise in the two eyes became anticorrelated, resulting in less binocular noise and therefore a binocular advantage in the discrimination task. Combining a nonlinear contrast transducer or MN with a binocular combination model (DSKL) provides a powerful method for evaluating the two putative contrast-discrimination mechanisms.
关键词： anticorrelation,fixation point,interocular enhancement,accommodation fluctuation,interocular inhibition,binocular advantage,singularity,gain-control of gain-control,nonlinear contrast transducer,contrast-gain control
更新于2025-09-04 15:30:14
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Fixation Stability Measurement Using Two Types of Microperimetry Devices
摘要： Purpose: We compared the fixation stability measurements obtained with two microperimeters, the Micro Perimeter 1 (MP-1) and the Spectral OCT/SLO (OCT/SLO), in subjects with and without maculopathies. Methods: A total of 41 eyes with no known ocular diseases and 45 eyes with maculopathies were enrolled in the study. Both eyes of each participant had a 20-second fixation test using the MP-1 and OCT/SLO. The bivariate contour ellipse area (BCEA) was used for fixation stability evaluation. Results: In the normal group, BCEA was 2.93 6 0.32 log minarc2 on OCT/SLO and 2.89 6 0.30 log minarc2 on MP-1. In the maculopathy group, BCEA was 3.05 6 0.41 log minarc2 on OCT/SLO and 3.15 6 0.46 log minarc2 on MP-1. There was no statistically significant difference between the BCEA measured by OCT/SLO and by MP-1 in both groups. A moderate correlation was found between the two devices (r ? 0.45, P , 0.001). The sample size during the fixation test was 535.5 6 14.6 pairs of coordinates in the normal group and 530.7 6 14.9 pairs in the maculopathy group with MP-1, while it was 72.3 6 6.9 and 59.9 6 10.1, respectively, with OCT/SLO. This was due to different tracking frequencies between the two microperimeters. Conclusion: Fixation stability assessment yields similar results using the OCT/SLO and MP-1. A major difference in sampling rate between the two microperimeters does not significantly affect BCEA measurements. Translational Relevance: Fixation stability assessments are comparable and interchangeable between the OCT/SLO and the MP-1.
关键词： fixation stability,comparison,microperimetry
更新于2025-09-04 15:30:14