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https://www.readbyqxmd.com/read/29934802/iscev-extended-protocol-for-the-photopic-on-off-erg
#1
Maja Sustar, Graham E Holder, Jan Kremers, Claire S Barnes, Bo Lei, Naheed W Khan, Anthony G Robson
The International Society for Clinical Electrophysiology of Vision (ISCEV) standard for full-field electroretinography (ERG) describes a minimum procedure, but encourages more extensive testing. This ISCEV extended protocol describes an extension to the ERG standard, namely the photopic On-Off ERG, and outlines common clinical applications. A light stimulus duration of 150-200 ms is used in the presence of a rod-suppressing background to elicit cone-driven On- and Off-system ERG components. The On-response occurs after the stimulus onset and has a negative a-wave and positive b-wave...
June 22, 2018: Documenta Ophthalmologica. Advances in Ophthalmology
https://www.readbyqxmd.com/read/29934801/iscev-extended-protocol-for-the-dark-adapted-red-flash-erg
#2
Dorothy A Thompson, Kaoru Fujinami, Ido Perlman, Ruth Hamilton, Anthony G Robson
The International Society for Clinical Electrophysiology of Vision (ISCEV) standard for full-field electroretinography (ERG) describes a minimum procedure, but encourages more extensive testing. This ISCEV extended protocol describes an extension to the ERG standard, namely the dark-adapted (DA) red flash ERG. The DA red flash ERG can be incorporated conveniently within the ISCEV standard ERG protocol after a minimum of 20-min DA and recorded after the DA 0.01 ERG to a flash strength of 0.3 phot cd s m-2 , eliciting a waveform with two positive peaks in healthy individuals...
June 22, 2018: Documenta Ophthalmologica. Advances in Ophthalmology
https://www.readbyqxmd.com/read/29888430/contrary-to-popular-belief-chinchillas-do-not-have-a-pure-rod-retina
#3
Shai Sandalon, Anna Boykova, Maya Ross, Alexey Obolensky, Eyal Banin, Ron Ofri
PURPOSE: To establish whether there is cone contribution to retinal function and structure in chinchillas (Chinchilla lanigera), in view of the prevailing notion that this species possesses a pure rod retina. METHODS: Photopic electroretinography (ERG) responses to high-intensity flashes (10 and 25 cd*s/m2 ) were recorded unilaterally in six pigmented chinchillas following 10 minutes of light adaptation (30 cd/m2 ). Retinas of two animals were studied histologically, and immunohistochemistry (IHC) was conducted to detect the presence of short and medium/long wavelength cone photoreceptors...
June 10, 2018: Veterinary Ophthalmology
https://www.readbyqxmd.com/read/29858967/dark-adapted-red-flash-ergs-in-healthy-adults
#4
R Hamilton, K Graham
PURPOSE: The x-wave of the dark-adapted (DA) ERG to a red flash reflects DA cone function. This exploratory study of healthy adults aimed to investigate changes in the DA red ERG with flash strength and during dark adaptation to optimise visualisation and therefore quantification of the x-wave. METHODS: The effect of altering red flash strength was investigated in four subjects by recording ERGs after 20 min dark adaptation to red flashes (0.2-2.0 cd s m-2 ) using skin electrodes and natural pupils...
June 1, 2018: Documenta Ophthalmologica. Advances in Ophthalmology
https://www.readbyqxmd.com/read/29721988/role-of-sirtuins-in-retinal-function-under-basal-conditions
#5
Jonathan B Lin, Shunsuke Kubota, Raul Mostoslavsky, Rajendra S Apte
Sirtuins are NAD+ -dependent enzymes that govern cellular homeostasis by regulating the acylation status of their diverse target proteins. We recently demonstrated that both rod and cone photoreceptors rely on NAMPT-mediated NAD+ biosynthesis to meet their energetic requirements. Moreover, we found that this NAD+ -dependent retinal homeostasis relies, in part, on maintenance of optimal activity of the mitochondrial sirtuins and of SIRT3 in particular. Nonetheless, it is unknown whether other sirtuin family members also play important roles in retinal homeostasis...
2018: Advances in Experimental Medicine and Biology
https://www.readbyqxmd.com/read/29684405/moderate-perinatal-thyroid-hormone-insufficiency-alters-visual-system-function-in-adult-rats
#6
William K Boyes, Laura Degn, Barbara Jane George, Mary E Gilbert
Thyroid hormone (TH) is critical for many aspects of neurodevelopment and can be disrupted by a variety of environmental contaminants. Sensory systems, including audition and vision are vulnerable to TH insufficiencies, but little data are available on visual system development at less than severe levels of TH deprivation. The goal of the current experiments was to explore dose-response relations between graded levels of TH insufficiency during development and the visual function of adult offspring. Pregnant Long Evans rats received 0 or 3 ppm (Experiment 1), or 0, 1, 2, or 3 ppm (Experiment 2) of propylthiouracil (PTU), an inhibitor of thyroid hormone synthesis, in drinking water from gestation day (GD) 6 to postnatal day (PN) 21...
April 21, 2018: Neurotoxicology
https://www.readbyqxmd.com/read/29603933/human-s-cone-electroretinograms-obtained-by-silent-substitution-stimulation
#7
J Maguire, N R A Parry, J Kremers, I J Murray, D McKeefry
We used triple silent substitution stimuli to characterize human S-cone electroretinograms (ERGs) in normal trichromats. Short-wavelength-cone (S-cone) ERGs were found to have different morphological features and temporal frequency response characteristics compared to ERGs derived from L-cones, M-cones, and rod photoreceptors in normal participants. Furthermore, in two cases of retinal pathology, blue cone monochromatism (BCM) and enhanced S-cone syndrome (ESCS), S-cone ERGs elicited by our stimuli were preserved and enhanced, respectively...
April 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
https://www.readbyqxmd.com/read/29518352/loss-of-cone-function-without-degeneration-in-a-novel-gnat2-knock-out-mouse
#8
Kaitryn E Ronning, Gabriel Peinado Allina, Eric B Miller, Robert J Zawadzki, Edward N Pugh, Rolf Herrmann, Marie E Burns
Rods and cones mediate visual perception over 9 log units of light intensities, with both photoreceptor types contributing to a middle 3-log unit range that comprises most night-time conditions. Rod function in this mesopic range has been difficult to isolate and study in vivo because of the paucity of mutants that abolish cone signaling without causing photoreceptor degeneration. Here we describe a novel Gnat2 knockout mouse line (Gnat2-/- ) ideal for dissecting rod and cone function. In this line, loss of Gnat2 expression abolished cone phototransduction, yet there was no loss of cones, disruption of the photoreceptor mosaic, nor change in general retinal morphology up to at least 9 months of age...
March 5, 2018: Experimental Eye Research
https://www.readbyqxmd.com/read/29420665/electroretinographic-evidence-suggesting-that-the-type-2-diabetic-retinopathy-of-the-sand-rat-psammomys-obesus-is-comparable-to-that-of-humans
#9
COMPARATIVE STUDY
Ahmed Dellaa, Maha Benlarbi, Imane Hammoum, Nouha Gammoudi, Mohamed Dogui, Riadh Messaoud, Rached Azaiz, Ridha Charfeddine, Moncef Khairallah, Pierre Lachapelle, Rafika Ben Chaouacha-Chekir
PURPOSE: Type 2 diabetic retinopathy is the main cause of acquired blindness in adults. The aim of this work was to examine the retinal function of the sand rat Psammomys obesus as an animal model of diet-induced type 2 diabetes when subjected to a hypercaloric regimen. MATERIALS AND METHODS: Hyperglycemia was induced in Psammomys obesus by high caloric diet (4 kcal/g). The visual function of control (n = 7) and diabetic (n = 7) adult rodents were followed up during 28 consecutive weeks with full-field electroretinogram(ERG) recordings evoked to flashes of white light according to the standard protocol of the International Society for Clinical Electrophysiology of Vision protocol (ISCEV)...
2018: PloS One
https://www.readbyqxmd.com/read/29385733/autosomal-recessive-nrl-mutations-in-patients-with-enhanced-s-cone-syndrome
#10
Karin W Littink, Patricia T Y Stappers, Frans C C Riemslag, Herman E Talsma, Maria M van Genderen, Frans P M Cremers, Rob W J Collin, L Ingeborgh van den Born
Enhanced S-cone syndrome (ESCS) is mainly associated with mutations in the NR2E3 gene. However, rare mutations in the NRL gene have been reported in patients with ESCS. We report on an ESCS phenotype in additional patients with autosomal recessive NRL (ar NRL ) mutations. Three Moroccan patients of two different families with ar NRL mutations were enrolled in this study. The mutation in the DNA of one patient, from a consanguineous marriage, was detected by homozygosity mapping. The mutation in the DNA of two siblings from a second family was detected in a targeted next-generation sequencing project...
January 30, 2018: Genes
https://www.readbyqxmd.com/read/29131863/long-term-retinal-cone-rescue-using-a-capsid-mutant-aav8-vector-in-a-mouse-model-of-cnga3-achromatopsia
#11
Xufeng Dai, Ying He, Hua Zhang, Yangyang Zhang, Yan Liu, Muran Wang, Hao Chen, Ji-Jing Pang
Adeno-associated virus (AAV) vectors are important gene delivery tools for the treatment of many recessively inherited retinal diseases. For example, a wild-type (WT) AAV5 vector can deliver a full-length Cnga3 (cyclic nucleotide-gated channel alpha-3) cDNA to target cells of the cone photoreceptor function loss 5 (cpfl5) mouse, a spontaneous animal model of achromatopsia with a Cnga3 mutation. Gene therapy restores cone-mediated function and blocks cone degeneration in the mice. However, since transgene expression delivered by an AAV vector shows relatively short-term effectiveness, this cannot be regarded as a very successful therapy...
2017: PloS One
https://www.readbyqxmd.com/read/28993665/variabilities-in-retinal-function-and-structure-in-a-canine-model-of-cone-rod-dystrophy-associated-with-rpgrip1-support-multigenic-etiology
#12
Rueben G Das, Felipe Pompeo Marinho, Simone Iwabe, Evelyn Santana, Kendra Sierra McDaid, Gustavo D Aguirre, Keiko Miyadera
Defects in the cilia gene RPGRIP1 cause Leber congenital amaurosis and cone-rod dystrophy in humans. A form of canine cone-rod dystrophy (cord1) was originally associated with a homozygous insertion in RPGRIP1 (RPGRIP1 ins/ins ) as the primary disease locus while a homozygous deletion in MAP9 (MAP9 del/del ) was later identified as a modifier associated with the early onset form. However, we find further variability in cone electroretinograms (ERGs) ranging from normal to absent in an extended RPGRIP1 ins/ins canine colony, irrespective of the MAP9 genotype...
October 9, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28975461/measurement-of-dark-adaptometry-during-iscev-standard-flash-electroretinography
#13
Jeff Rabin, Brooke Houser, Carolyn Talbert, Rue Patel
PURPOSE: Dark adaptometry (DA) is a sensitive test for diagnosis of retinal disease. Patients requiring flash electroretinograms (ERGs) benefit from DA for proper diagnosis. Our purpose was to develop a DA test to be administered during the 20-min dark adaptation period of the flash ERG ( www.iscev.org ) using alternating red and blue stimuli to bias responses in favor of cones (red) and rods (blue). METHODS: An ERG Ganzfeld was used to measure DA in 21 normal subjects and 21 patients with retinal disease...
December 2017: Documenta Ophthalmologica. Advances in Ophthalmology
https://www.readbyqxmd.com/read/28929832/cngb3-mutations-cause-severe-rod-dysfunction
#14
J Maguire, M McKibbin, K Khan, S Kohl, M Ali, D McKeefry
PURPOSE: Congenital achromatopsia or rod monochromatism is a rare autosomal recessive condition defined by a severe loss of cone photoreceptor function in which rods purportedly retain normal or near-to-normal function. This report describes the results of electroretinography in two siblings with CNGB3-associated achromatopsia. METHODS: Full field light- and dark-adapted electroretinograms (ERGs) were recorded using standard protocols detailed by the International Society for Clinical Electrophysiology of Vision (ISCEV)...
January 2018: Ophthalmic Genetics
https://www.readbyqxmd.com/read/28798898/dark-adapted-chromatic-perimetry-for-measuring-rod-visual-fields-in-patients-with-retinitis-pigmentosa
#15
Lea D Bennett, Martin Klein, Kirsten G Locke, Kelly Kiser, David G Birch
PURPOSE: Although rod photoreceptors are initially affected in retinitis pigmentosa (RP), the full-field of rod vision is not routinely characterized due to the unavailability of commercial devices detecting rod sensitivity. The purpose of this study was to quantify rod-mediated vision in the peripheral field from patients with RP using a new commercially available perimeter. METHODS: Participants had one eye dilated and dark-adapted for 45 minutes. A dark-adapted chromatic (DAC) perimeter tested 80 loci 144° horizontally and 72° vertically with cyan stimuli...
July 2017: Translational Vision Science & Technology
https://www.readbyqxmd.com/read/28662245/reduction-of-rod-and-cone-function-in-6-5-year-old-children-born-extremely-preterm
#16
COMPARATIVE STUDY
Anna E C Molnar, Sten O Andréasson, Eva K B Larsson, Hanna M Åkerblom, Gerd E Holmström
Importance: The function of rods and cones in children born extremely preterm has not yet been fully investigated. Objective: To compare retinal function via full-field electroretinographic (ffERG) recordings in 6.5-year-old children born extremely preterm with children born at term. Design, Setting, and Participants: A subcohort study was conducted from July 1, 2010, to January 15, 2014, of the national Extremely Preterm Infants in Sweden Study, including preterm children (<27 weeks' gestational age) and children born at term, at 6...
August 1, 2017: JAMA Ophthalmology
https://www.readbyqxmd.com/read/28593392/multimodal-imaging-and-functional-correlations-identify-unusual-cases-of-macular-retinal-pigment-epithelium-hypopigmentation-occurring-without-functional-loss
#17
E Boulanger-Scemama, J Akesbi, S Tick, S Mohand-Said, J-A Sahel, I Audo
PURPOSE: Patients with unusual macular retinal pigment epithelium (RPE) hypopigmentation are described and analyzed using retinal multimodal imaging. METHODS: We report three cases of patients with unilateral (2) or bilateral (1) macular lesions discovered incidentally on fundoscopy. A comprehensive ophthalmic examination including visual acuity, fundoscopy, spectral-domain optical coherence tomography (SD-OCT), short-wavelength light and near-infrared autofluorescence, fluorescein angiography, microperimetry, multifocal electroretinogram, adaptive optics (AO), and OCT-angiography (OCT-A) has been performed...
August 2017: Documenta Ophthalmologica. Advances in Ophthalmology
https://www.readbyqxmd.com/read/28516000/role-of-a-dual-splicing-and-amino-acid-code-in-myopia-cone-dysfunction-and-cone-dystrophy-associated-with-l-m-opsin-interchange-mutations
#18
Scott H Greenwald, James A Kuchenbecker, Jessica S Rowlan, Jay Neitz, Maureen Neitz
PURPOSE: Human long (L) and middle (M) wavelength cone opsin genes are highly variable due to intermixing. Two L/M cone opsin interchange mutants, designated LIAVA and LVAVA, are associated with clinical diagnoses, including red-green color vision deficiency, blue cone monochromacy, cone degeneration, myopia, and Bornholm Eye Disease. Because the protein and splicing codes are carried by the same nucleotides, intermixing L and M genes can cause disease by affecting protein structure and splicing...
May 2017: Translational Vision Science & Technology
https://www.readbyqxmd.com/read/28478700/safety-and-efficacy-evaluation-of-raav2tyf-pr1-7-hcnga3-vector-delivered-by-subretinal-injection-in-cnga3-mutant-achromatopsia-sheep
#19
Elisha Gootwine, Ron Ofri, Eyal Banin, Alexey Obolensky, Edward Averbukh, Raaya Ezra-Elia, Maya Ross, Hen Honig, Alexander Rosov, Esther Yamin, Guo-Jie Ye, David R Knop, Paulette M Robinson, Jeffrey D Chulay, Mark S Shearman
Applied Genetic Technologies Corporation (AGTC) is developing a recombinant adeno-associated virus (rAAV) vector expressing the human CNGA3 gene designated AGTC-402 (rAAV2tYF-PR1.7-hCNGA3) for the treatment of achromatopsia, an inherited retinal disorder characterized by markedly reduced visual acuity, extreme light sensitivity, and absence of color discrimination. The results are herein reported of a study evaluating safety and efficacy of AGTC-402 in CNGA3-deficient sheep. Thirteen day-blind sheep divided into three groups of four or five animals each received a subretinal injection of an AAV vector expressing a CNGA3 gene in a volume of 500 μL in the right eye...
June 2017: Human Gene Therapy. Clinical Development
https://www.readbyqxmd.com/read/28384671/acute-zonal-cone-photoreceptor-outer-segment-loss
#20
Tomas S Aleman, Harpal S Sandhu, Leona W Serrano, Anastasia Traband, Marisa K Lau, Grazyna Adamus, Robert A Avery
Importance: The diagnostic path presented narrows down the cause of acute vision loss to the cone photoreceptor outer segment and will refocus the search for the cause of similar currently idiopathic conditions. Objective: To describe the structural and functional associations found in a patient with acute zonal occult photoreceptor loss. Design, Setting, and Participants: A case report of an adolescent boy with acute visual field loss despite a normal fundus examination performed at a university teaching hospital...
May 1, 2017: JAMA Ophthalmology
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