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Night-vision aid using see-through display for patients with retinitis pigmentosa
摘要： Purpose From an early stage, retinitis pigmentosa (RP) patients suffer from night blindness which causes nocturnal mobility difficulties. We created a wearable visual aid that uses a high-performance see-through display, and added a high-sensitivity camera with a complementary metal-oxide-semiconductor sensor. Here, we evaluate the device’s efficacy for helping night-blindness sufferers walk in the dark. Study design Prospective clinical study. Methods Twenty-eight subjects underwent binocular visual acuity testing in the dark without (power off) and with (power on) the device. The test was carried out in a darkened room. We recorded the number of trial errors and the time it took each subject to arrive at the goal both with and without the aid of our device. Results Our device effectively assists walking in RP patients with mobility problems in the dark. Conclusion Binocular visual acuity in the dark was significantly improved with the aid of our device. In the walking test, the number of errors decreased greatly with the device, and the travel time was significantly shortened.
关键词： night blindness,retinitis pigmentosa,visual aids,see-through display
更新于2025-09-23 15:23:52
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Psychophysical measures of visual function and everyday perceptual experience in a case of congenital stationary night blindness
摘要： An appreciation of the relation between laboratory measures of visual deficit and everyday perceptual experience is fundamental to understanding the impact of a visual condition on patients and so to a fuller characterization of the disorder. This study aims to understand better the interpretative processes by which modified sensory information is perceived by a patient with congenital stationary night blindness and the adaptive strategies that are devised to deal with their measurable visual loss. Psychophysical measurements of temporal resolution, spectral sensitivity, and color discrimination were conducted on a 78-year-old male patient with the condition, who was also interviewed at length about the ways in which his diagnosis affected his daily life. Narrative analysis was employed to identify the relation between his subjective perceptual experiences and functional deficits in identifiable components of the visual system. Psychophysical measurements indicated a complete lack of rod perception and substantially reduced cone sensitivity. Two particular effects of this visual loss emerged during interviews: 1) the development of navigational techniques that relied on light reflections and point sources of light and 2) a reluctance to disclose the extent of visual loss and resulting lifelong psychosocial consequences. This study demonstrates the valuable complementary role that rich descriptive patient testimony can play, in conjunction with laboratory and clinical measurements, in more fully characterizing a disorder and in reaching a more complete understanding of the experience of vision loss. It also evidences the particular suitability of filmmaking techniques as a means of accessing and communicating subjective patient experience.
关键词： narrative analysis,congenital stationary night blindness,quality of life,GRM6 gene,perception,psychophysics
更新于2025-09-23 15:22:29
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Retinal degeneration 3 (RD3) protein, a retinal guanylyl cyclase regulator, forms a monomeric and elongated four helix bundle
摘要： Retinal degeneration 3 (RD3) protein promotes accumulation of retinal membrane guanylyl cyclase (RetGC) in photoreceptor outer segment and suppresses RetGC activation by guanylyl cyclase activating proteins (GCAPs). Mutations truncating RD3 cause severe congenital blindness by preventing the inhibitory binding of RD3 to the cyclase. The high propensity of RD3 to aggregate in solution has prevented structural analysis. Here, we produced a highly soluble variant of human RD3 (residues 18–160) that is monomeric and can still bind and negatively regulate RetGC. The NMR solution structure of RD3 revealed an elongated backbone structure (70? long and 30? wide), consisting of a four helix bundle with a long unstructured loop between helices 1 and 2. The structure reveals that RD3 residues previously implicated in RetGC binding map to a localized and contiguous area on the structure, involving a loop between helices 2 and 3 and adjacent parts of helices 3 and 4. The NMR structure of RD3 was validated by mutagenesis. Introducing Trp85 or Phe29 to replace Cys or Leu, respectively, disrupts packing in the hydrophobic core and lowers RD3’s apparent affinity for RetGC1. Introducing a positive charge at the interface (Glu32 to Lys), also lowered the affinity. Conversely, introducing Val in place of Cys93 stabilized the hydrophobic core and increased the RD3 affinity for the cyclase. The NMR structure of RD3 presented here provides a structural basis for elucidating RD3/RetGC interactions relevant for normal vision or blindness.
关键词： phototransduction,retina,NMR spectroscopy,guanylate cyclase (guanylyl cyclase),retinal degeneration 3 (RD3),photoreceptor,blindness
更新于2025-09-23 15:22:29
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Early Alteration of Retinal Neurons in <i>Aipl1</i> <sup>?/?</sup> Animals
摘要： PURPOSE. Mutations in the photoreceptor cell-specific gene encoding aryl hydrocarbon receptor-interacting protein-like 1 (AIPL1) lead to Leber congenital amaurosis (LCA4), retinitis pigmentosa, and cone–rod dystrophy. Gene therapy appears to be promising in the treatment for AIPL1-mediated vision loss in humans. Prior to initiating these treatments, however, it is crucial to understand how the retinal neurons remodel themselves in response to photoreceptor cell degeneration. In this study, using an animal model for AIPL1-LCA, Aipl1(cid:2)/(cid:2) mice, we investigate the changes in postreceptoral retinal neurons during the course of photoreceptor cell loss. METHODS. Morphology of the Aipl1(cid:2)/(cid:2) retina from postnatal day 8 to 150 was compared to that of age-matched, wild-type C57Bl6/J retina (WT) by immunocytochemistry using cell-specific markers. RESULTS. Expression of postsynaptic proteins in bipolar cells is reduced prior to photoreceptor cell degeneration at postnatal day 8. Bipolar and horizontal cells retract their dendrites. Cell bodies and axons of bipolar and horizontal cells are disorganized during the course of degeneration. M¨uller cell processes become hypertrophic and form a dense fibrotic layer outside the inner nuclear layer. CONCLUSIONS. An early defect in photoreceptor cells in the AIPL1-LCA mouse model affects the expression of postsynaptic markers, suggesting abnormal development of bipolar synapses. Once degeneration of photoreceptor cells is initiated, remodeling of retinal neurons in the Aipl1(cid:2)/(cid:2) animal is rapid.
关键词： childhood blindness,photoreceptor degeneration,retina,LCA,remodeling
更新于2025-09-23 15:22:29
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Wideband Wide-Scanning Phased Array in Triangular Lattice with Electromagnetic Band-Gap Structures
摘要： A phased array in triangular lattice, with a large element spacing, wide band and wide scan angle, is investigated in this paper. The array is designed based on a connected backed-cavity antenna element. Scan blindness is observed for this triangular lattice array when the beam scans in the E plane due to large element spacing which provides a suitable propagation condition for the leaky surface waves in the array aperture. Therefore, compact electromagnetic band-gap (EBG) structures are loaded in the array element to suppress the leaky surface waves and then remove the E-plane scan blindness for the largest impedance bandwidth. The bandwidths close to the theoretical values are achieved as the beam is scanned in the E and H planes, for the given element spacing. The validity of design is verified by fabricating a 13×5 prototype, the measured results are in good agreements with the full-wave simulations.
关键词： scan blindness,phased arrays,wide scanning,Electromagnetic band-gap (EBG) structures,triangular lattice
更新于2025-09-19 17:15:36
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Handbook of Bioelectronics (Directly Interfacing Electronics and Biological Systems) || Photovoltaic retinal prosthesis for restoring sight to the blind
摘要： Age-related macular degeneration (AMD) is one of the leading causes of blindness in the developed world, with an incidence of 1:500 in patients aged 55–64, and 1:8 in patients over 85 [1]. Retinitis pigmentosa (RP) is an inherited disease blinding about 1 in every 4000 individuals much earlier in life [2]. In both of these conditions the photoreceptor layer degenerates, while the inner retinal neurons survive to a large extent [3–5]. Electrically activating these neurons provides an alternative route for visual information and raises hope for the restoration of sight to the blind.
关键词： age-related macular degeneration,restoring sight,Photovoltaic retinal prosthesis,blindness,retinitis pigmentosa
更新于2025-09-12 10:27:22
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Molecular Diagnosis of Inherited Retinal Diseases in Indigenous African Populations by Whole-Exome Sequencing
摘要： PURPOSE. A majority of genes associated with inherited retinal diseases (IRDs) have been identi?ed in patients of European origin. Indigenous African populations exhibit rich genomic diversity, and evaluation of reported genetic mutations has yielded low returns so far. Our goal was to perform whole-exome sequencing (WES) to examine variants in known IRD genes in underrepresented African cohorts. METHODS. Whole-exome sequencing was performed on 56 samples from 16 families with diverse IRD phenotypes that had remained undiagnosed after screening for known mutations using genotyping-based microarrays (Asper Ophthalmics). Variants in reported IRD genes were identi?ed using WES and validated by Sanger sequencing. Custom TaqMan assays were used to screen for identi?ed mutations in 193 unrelated indigenous Africans with IRDs. RESULTS. A total of 3494 variants were identi?ed in 217 known IRD genes, leading to the identi?cation of seven different mutations (including six novel) in six genes (RHO, PRPF3, PRPF31, ABCA4, CERKL, and PDE6B) in six distinct families. TaqMan screening in additional probands revealed identical homozygous CERKL and PDE6B variants in four more patients. CONCLUSIONS. This is the ?rst report of WES of patients with IRDs in indigenous African populations. Our study identi?ed genetic defects in almost 40% of the families analyzed, signi?cantly enhancing the molecular diagnosis of IRD in South Africa. Thus, WES of understudied cohorts seems to present an effective strategy for determining novel mutations in heterogeneous retinal diseases.
关键词： genetic testing,vision loss,inherited blindness,South Africa,retinal degeneration,next generation sequencing,photoreceptor dysfunction,clinical genetics
更新于2025-09-11 14:15:04
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Diabetic Nephropathy (Pathophysiology and Clinical Aspects) || Microvascular Complications in the?Eye: Diabetic Retinopathy
摘要： Diabetic retinopathy (DR) is a major cause of vision loss and blindness among persons with diabetes mellitus. It is estimated that approximately 35% of diabetes patients develop some form of DR [1]. DR is a progressive disease that is predominantly characterized by alterations in the retinal microvasculature. It may develop from an asymptomatic nonproliferative form associated with capillary non-perfusion, microaneurysms, and retinal hemorrhages, into a vision-threating disorder such as diabetic macular edema (DME) and proliferative DR (PDR).
关键词： vision loss,Diabetic retinopathy,retinal microvasculature,blindness,microvascular complications,diabetic macular edema,diabetes mellitus,proliferative diabetic retinopathy
更新于2025-09-10 09:29:36
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Photoreceptor degeneration in a new Cacna1f mutant mouse model
摘要： The Cacna1f gene encodes the α1F subunit of an L-type voltage-gated calcium channel, Cav1.4. In photoreceptor synaptic terminals, Cav1.4 channels mediate glutamate release and postsynaptic responses associated with visual signal transmission. We have discovered a new Cacna1f mutation in nob9 mice, which display more severe phenotypes than do nob2 mice. To characterize the nob9 phenotype at different ages, we examined the murine fundus, applied retinal optical coherence tomography, measured flash electroretinograms (ERGs) in vivo, and analyzed the retinal histology in vitro. After identifying the X-linked recessive inheritance trait, we sequenced Cacna1f as the candidate gene. Mutations in this gene were detected by polymerase chain reaction (PCR) and confirmed by restriction fragment length polymorphism. Morphologically, an early-onset of retinal disorder was detected, and the degeneration of the outer plexiform layers progressed rapidly. Moreover, the mutant mice showed drastically reduced scotopic ERGs with increasing age. In 14-month-old nob9 retinas, immunostaining of cone opsins demonstrated a reduction in the number of short-wavelength opsins (S-opsins) to 54% of wild-type levels, and almost no middle-wavelength opsins (M-opsins) were observed. No cone ERGs could be detected from residual cones, in which S-opsins abnormally migrated to inner segments of the photoreceptors. The mutations of the Cacna1f gene in nob9 mice involved both a single nucleotide G to A transition and a 10-nucleotide insertion, the latter resulting in a frame-shift mutation in exon 14.
关键词： X-linked recessive inheritance,Electroretinogram,Congenital stationary night blindness,Mice,Cone opsins
更新于2025-09-10 09:29:36
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[IEEE 2018 International Conference on Advances in Computing, Communications and Informatics (ICACCI) - Bangalore, India (2018.9.19-2018.9.22)] 2018 International Conference on Advances in Computing, Communications and Informatics (ICACCI) - Detection of Exudates in Diabetic Retinopathy
摘要： Diabetic Retinopathy (DR) is an eye abnormality in which the human retina will get affected and is becoming one of the leading cause of preventable blindness. In the world, it is found that nearly 4.8% of blindness is caused due to DR. Preliminary symptoms include the formation of microaneurysms, exudates and hemorrhages. Early detection of DR can save the vision of diabetes patients and manual diagnosis takes time and effort for confirmation. In this paper, a Computer-aided Automated Diagnosis (CAD) is developed to solve this problem. The proposed approach uses edge-based segmentation method for segmenting the optic disc and blood vessels more accurately than region-based methods, followed by extraction of most probable exudates regions, feature extraction and the classifier stage to detect the presence of exudates. This system achieved sensitivity 82.61%, specificity 92.31% and moreover an accuracy of 87.75% for DIARETDB dataset.
关键词： Blindness,edge-based segmentation,Diabetic Retinopathy,CAD,exudates,NPDR,PDR
更新于2025-09-09 09:28:46