From vision to cognition: potential contributions of cerebral visual impairment to neurodevelopmental disorders.

Vision has a crucial role to play in human development and functioning. It is, therefore, not surprising that vision plays a fundamental role in the development of the child. As a consequence, an alteration in visual function is, therefore, likely to hinder the child's development. Although ocular disorders are well known, diagnosed and taken into account, cerebral visual impairments (CVI) resulting from post-chiasmatic damage are largely underdiagnosed. However, among the disorders resulting from an episode of perinatal asphyxia and/or associated with prematurity, or neonatal hypoglycaemia, CVIs are prominent. In this article, we focus on the role of the possible effects of CVI on a child's learning abilities, leading to major difficulty in disentangling the consequences of CVI from other neurodevelopmental disorders (NDD) such as dyslexia, dyscalculia, dysgraphia, attention-deficit/hyperactivity disorder (ADHD), developmental coordination disorder (DCD) and autism spectrum disorders (ASD). Although we focus here on the possible overlap between children with CVI and children with other NDD, De Witt et al. (Wit et al. Ear Hear 39:1-19, 2018) have raised exactly the same question regarding children with auditory processing disorders (the equivalent of CVI in the auditory modality). We underline how motor, social and cognitive development as well as academic success can be impaired by CVI and raise the question of the need for systematic evaluation for disorders of vision, visual perception and cognition in all children presenting with a NDD and/or previously born under adverse neurological conditions.

Early visual training and environmental adaptation for infants with visual impairment.

AIM: To evaluate the effectiveness of early visual training and environmental adaptation on visual function and neurological development in infants with visual impairment. METHOD: This was a pilot intervention clinical trial study. Thirty infants (mean age 5.9mo, SD 2.1mo, range 4-11mo; 16 males, 14 females) with peripheral visual impairment (PVI, n=15) or cerebral visual impairment (CVI, n=15) participated in a 6-month visual intervention programme. Thirty matched infants (mean age 6mo, SD 1.4mo, range 4-9mo; 18 males, 12 females) served as a comparison group. Primary outcome measures were visual acuity, contrast sensitivity, and qualitative ocular motor functions. Secondary outcomes were scores on the Griffiths Mental Developmental Scales (GMDS). RESULTS: The treatment group showed a significant improvement in all the primary outcomes (p<0.01). The comparison group improved only in visual acuity and contrast sensitivity (p<0.01). The treatment group showed greater improvement than the comparison group in visual fixation (p=0.033) and smooth pursuit (p<0.01). The CVI subgroup showed greater improvement in visual acuity than the PVI subgroup (p<0.01). GMDS subscales of hand-eye coordination (p=0.01) and performance (p<0.01) increased in the treatment group, while the total score of the comparison group decreased, driven by language (p=0.039) and hand-eye coordination (p=0.025) subscales. INTERPRETATION: Results suggest that, in infants with visual impairment, visual function and certain developmental outcomes improve in response to early visual training and environmental adaptation, in an interactive context. What this paper adds Early visual training and environmental adaptation are associated with enhanced visual acuity and smooth pursuit. Early visual training and environmental adaptation are associated with an improvement of neurological developmental outcome. Performance, hand-eye coordination, and language scores in Griffiths Mental Developmental Scales increase after visual training. After training, visual acuity improves more in infants with cerebral rather than anterior visual impairment. Type and complexity of visual impairment contribute to determine infants' response to training.

Brain structure in children with congenital visual disorders and visual impairment.

AIM: To examine if congenital visual impairment is associated with differences in brain anatomy in children. METHOD: Ten children (8-12y) with congenital disorders of the peripheral visual system with severe visual impairment (SVI; >0.8 logMAR) or mild-to-moderate visual impairment (MVI; 0.6-0.8 logMAR) were compared to 21 typically sighted comparison (TSC) children. Thalamus volume, grey matter density, white matter microstructure, and integrity of visual tracts were investigated in SVI, MVI, and TSC groups with anatomical and diffusion-weighted magnetic resonance imaging. RESULTS: Compared to the TSC group, the SVI group had lower white matter integrity in tracts of the visual system (optic radiations: SVI 0.35±0.015, TSC 0.39±0.007 [p=0.022]; posterior corpus callosum: SVI 0.37±0.019; TSC 0.42±0.009 [p=0.033]) and lower left thalamus volume (SVI 4.37±0.087; TSC 4.99±0.339 [p=0.015]). Neuroanatomical differences were greater in the SVI group, while no consistent differences between the MVI and TSC group were observed. INTERPRETATION: Posterior tracts of the visual system are compromised in children with congenital visual impairment versus those who are typically sighted. The severity of visual input appears to have affected neuroanatomical development as significant reductions were only found in the SVI group. WHAT THIS PAPER ADDS: Severe visual impairment in mid-childhood is associated with reduced integrity of visual pathways and reduced thalamus volume.

Micro-probing enables fine-grained mapping of neuronal populations using fMRI.

The characterization of receptive field (RF) properties is fundamental to understanding the neural basis of sensory and cognitive behaviour. The combination of non-invasive imaging, such as fMRI, with biologically inspired neural modelling has enabled the estimation of population RFs directly in humans. However, current approaches require making numerous a priori assumptions, so these cannot reveal unpredicted properties, such as fragmented RFs or subpopulations. This is a critical limitation in studies on adaptation, pathology or reorganization. Here, we introduce micro-probing (MP), a technique for fine-grained and largely assumption free characterization of multiple pRFs within a voxel. It overcomes many limitations of current approaches by enabling detection of unexpected RF shapes, properties and subpopulations, by enhancing the spatial detail with which we analyze the data. MP is based on tiny, fixed-size, Gaussian models that efficiently sample the entire visual space and create fine-grained probe maps. Subsequently, we derived population receptive fields (pRFs) from these maps. We demonstrate the scope of our method through simulations and by mapping the visual fields of healthy participants and of a patient group with highly abnormal RFs due to a congenital pathway disorder. Without using specific stimuli or adapted models, MP mapped the bilateral pRFs characteristic of observers with albinism. In healthy observers, MP revealed that voxels may capture the activity of multiple subpopulations RFs that sample distinct regions of the visual field. Thus, MP provides a versatile framework to visualize, analyze and model, without restrictions, the diverse RFs of cortical subpopulations in health and disease.

Risk factors associated with congenital defects that alter hearing or vision in children born in the city of Bogotá between 2002 and 2016.

INTRODUCTION: Congenital defects affecting the auditory and visual capacity of newborns represent a public health problem as they result in substantial disability, directly impacting the quality of life of newborns and their families. OBJECTIVE: To evaluate risk factors associated with congenital defects that alter hearing or vision in newborns in the city of Bogotá between 2002 and 2016. METHOD: Data from the Bogotá Birth Defects Surveillance and Follow-up Program was used, which consolidated data regarding 167 ECLAMC study (Estudio Colaborativo Latino Americano de Malformaciones Congénitas, in spanish) variables in a case-control design to identify risk factors for birth defects after parents provided signed informed consent. Cases were defined as any newborn (alive or stillborn) with a weight greater than 500 g with any visual or hearing abnormality. Controls were defined as newborn in the same hospital and month with no birth defects. Groups were formed according to the case presentation as follows: isolated eye anomaly, isolated ear anomaly, polymalformative, syndromic, and teratogenic. RESULTS: In total, 402,657 births were reviewed, of which 968 cases had some congenital defects that alter hearing or vision. An association was found between the presence of defects and prematurity, as well as between syndromic cases and increasing maternal age. When comparing cases and controls with the risk of having a birth defect, multiparity had an odds ratio (OR) of 1.47 (95% CI: 1.27-1.71), acute respiratory infection had an OR of 2.41 (95% CI: 1.04-5.58), low maternal education level had an OR of 1.34 (95% CI:1.10-1.62), low paternal education had an OR of 1.42, (95% CI:1.17-1.73), manual labor in the maternal occupation had an OR of 1.31 (95% CI:1.03-1.67), and a history of congenital anomalies in the family had an OR of 1.55 (95% CI:1.19-2.00). CONCLUSION: This research allowed the identification of epidemiological data and significant risk factors for congenital defects that alter hearing or vision in the population of Bogotá.

Adaptive behaviour and quality of life in school-age children with congenital visual disorders and different levels of visual impairment.

BACKGROUND: Adaptive behaviours are vital skills that allow individuals to function independently and are potentially amenable to behavioural interventions. Previous research indicated that adaptive behaviours are reduced in children and adolescents with severe to profound VI, but it was unclear if this was also the case for children with mild to moderate VI. AIM: The aim of the study was to assess differences in adaptive behaviour in children with congenital visual disorders and different levels of visual impairment and their influence on quality of life and everyday strengths and difficulties. METHODS AND PROCEDURES: Questionnaires about adaptive behaviour, strengths and difficulties, and quality of life were completed by parents of school-age children with severe-to-profound VI (S/PVI, n = 9, 0.9 logMAR - light perception only), mild-to-moderate VI (MVI, n = 9, 0.1-0.7 logMAR), or typical sight (control, n = 18, -0.3 to 0.1 logMAR). Differences in questionnaire domains by the severity of VI and relationships between adaptive behaviour and quality of life were analysed in general linear models. OUTCOMES AND RESULTS: The questionnaire ratings indicated reduced adaptive behaviour, more difficulties, and reduced quality of life in children with S/PVI compared to typically-sighted peers. Effects were smaller for children with MVI, but indicated a significant reduction in quality of life compared to typically-sighted children. The effect of visual impairment on quality of life in school was partially mediated by adaptive behaviour. CONCLUSION AND IMPLICATION: Severe congenital visual impairment affects adaptive behaviour in children with verbal abilities in the typical range. This effect is less pronounced in children with mild-to-moderate VI, but still impacts on quality of life, particularly in school.

Home-based early intervention in infants and young children with visual impairment using the Developmental Journal: longitudinal cohort study.

AIM: To investigate the effects of home-based early intervention in children with severe visual impairment (SVI) using the Developmental Journal for babies and young children with visual impairment (DJVI). METHOD: A longitudinal observational study was undertaken with a national cohort (OPTIMUM) of infants with congenital disorders of the peripheral visual system (CDPVS) and profound-SVI; and followed up after 12 months and 24 months. Intervention was categorized according to the practitioner diary records of their usual practice over 12 months from baseline comparing those receiving the DJVI and those receiving 'Other Support'. Outcome measures of cognition and language, behaviour difficulties, parenting stress, and satisfaction with parent-practitioner partnership were collected. RESULTS: In the 54 children (26 males, 28 females, baseline mean age 13.5mo, SD 2.3mo, range 8-17mo) with 'total' CDPVS (including 16 'complex' and 38 'simple' with or without known brain disorder respectively), linear mixed effects pointed towards acceleration in sensorimotor understanding and expressive language especially in the 'simple' subsample (11.72 developmental quotient, 95% confidence interval -1.17 to 24.61, p>0.05) in those receiving the DJVI. Vision level also predicted outcomes (p<0.05). The DJVI group showed improvements in behavioural withdrawal (η2 =0.20, p=0.02, 'simple') and parenting stress (d=0.78, d=0.92, p=0.02 total and 'simple' respectively) and perceived practitioner-parent relationship (η2 =0.16, p=0.01). INTERPRETATION: Infants and young children with visual impairment receiving home-based early intervention using the DJVI with a structured developmental approach had better outcomes than those receiving 'other' home-based early interventions. Moderate to large effect improvements were found in child cognition and language, behaviour and parenting stress and the perceived practitioner-parent relationship, although cognition did not reach 5% significance level. WHAT THIS PAPER ADDS: Early intervention using the Developmental Journal for babies and young children with visual impairment was associated with enhanced developmental outcomes compared to other approaches. Improvements were also found in child behaviour, parenting stress, and perceived parent practitioner outcomes. Type and complexity of visual impairment also influenced outcomes.

INTERVENCIÓN TEMPRANA DOMICILIARIA EN LACTANTES Y NIÑOS PEQUEÑOS CON DISCAPACIDAD VISUAL USANDO EL DIARIO DE DESARROLLO: ESTUDIO LONGITUDINAL DE COHORTE: OBJETIVO: Investigar los efectos de la intervención temprana en el hogar en niños con discapacidad visual grave utilizando el Diario de Desarrollo para bebés y niños pequeños con discapacidad visual (DJVI). MÉTODO: Se realizó un estudio observacional longitudinal con una cohorte nacional (OPTIMUM) de bebés con trastornos congénitos del sistema visual periférico (CDPVS) y discapacidad visual profunda-severa; y seguimiento después de 12 meses y 24 meses. La intervención se categorizó de acuerdo con los registros del diario de desarrollo del médico en su práctica habitual más de 12 meses desde el inicio, comparando los que recibieron el DJVI y los que recibieron "otro apoyo". Se recopilaron las medidas de resultado de la cognición y el lenguaje, las dificultades de comportamiento, el estrés de los padres y la satisfacción con la asociación entre padres y profesionales. RESULTADOS: En los 54 niños (26 varones, 28 mujeres, edad media de referencia 13,5 meses, DS 2,3 meses, rango 8-17 meses) con CDPVS 'total' (incluidos 16 'complejo' y 38 'simple' con o sin trastorno cerebral conocido respectivamente), los efectos mixtos lineales apuntan hacia la aceleración en la comprensión sensoriomotora y el lenguaje expresivo, especialmente en la submuestra "simple" (cociente de desarrollo 11,72, intervalo de confianza del 95% -1,17 a 24,61, p>0,05) en los que recibieron el DJVI. El nivel de visión también predijo resultados (p <0,05). El grupo DJVI mostró mejoras en la abstinencia conductual (η2 =0,20, p=0,02, 'simple') y el estrés parental (d=0,78 − d=0,92, p=0,02 total y 'simple' respectivamente) y la relación percibida entre el médico y el padre (η2 =0,16, p=0,01). INTERPRETACIÓN: Los bebés y niños pequeños con discapacidad visual que recibieron una intervención temprana en el hogar utilizando el DJVI, con un enfoque de desarrollo estructurado, tuvieron mejores resultados que los que recibieron "otras" intervenciones tempranas en el hogar. Se encontraron mejoras de efecto moderado a grande en la cognición infantil y el lenguaje, el comportamiento y el estrés parental y la relación percibida entre el médico y el padre, aunque la cognición no alcanzó el nivel de significación del 5%.

INTERVENÇÃO PRECOCE DOMICILIAR EM LACTENTES E CRIANÇAS JOVENS COM DEFICIÊNCIA VISUAL USANDO O DEVELOPMENTAL JOURNAL: ESTUDO DE COORTE LONGITUDINAL: OBJETIVO: Investigar os efeitos da intervenção precoce domiciliar em crianças com deficiência visual severa usando o Developmental Journal para lactentes e crianças jovens com deficiência visual (DJDV). METODO: Um estudo observacional longitudinal foi realizado com uma coorte nacional (OPTIMUM) de crianças com distúrbios congênitos do sistema visual periférico (DCSVP) e deficiência visual grave-profunda, estes foram acompanhados após 12 meses e 24 meses. A intervenção foi categorizada de acordo com os registros diários do profissional de sua prática habitual ao longo de 12 meses, a partir de uma linha de base, comparando aqueles que receberam a DJDV e os que receberam "outro suporte". Resultados dos testes de cognição e linguagem, dificuldades de comportamento, estresse parental e satisfação com a parceria entre pais e profissionais, foram coletados. RESULTADOS: Nas 54 crianças (26 do sexo masculino e 28 do feminino, média de idade na linha de base de 13,5 meses; DP 2,3 meses; variação de 8 a 17 meses) com DCSVP total (incluindo 16 'complexos' e 38 'simples' com ou sem distúrbio cerebral conhecido, respectivamente), efeitos mistos lineares apontaram para um avanço na compreensão sensório-motora e de linguagem expressiva, especialmente, no subgrupo 'simples' (11,72 quociente de desenvolvimento, IC 95% -1,17 a 24,61; p>0,05) naqueles que receberam o DJDV. Nível visual também foi preditivo dos desfechos (p<0,05). O grupo DJDV apresentou melhora no comportamento de retraimento social (η2 =0,20; p=0,02; 'simples'), no estresse parental (d=0,78 − d=0,92; p=0,02 total e 'simples', respectivamente) e na percepção do relacionamento profissional-pais (η2 =0,16; p=0,01). INTERPRETAÇÃO: Lactentes e crianças jovens com deficiência visual que recebem intervenção domiciliar precoce usando a DJVI com uma abordagem de desenvolvimento estruturado tiveram resultados melhores do que aqueles que receberam "outras" intervenções precoces em casa. Melhorias com efeito de moderado a grande foram encontradas na cognição e linguagem, no comportamento infantil e estresse parental, e no relacionamento percebido entre pais e profissionais, embora a cognição não tenha alcançado nível de significância de 5%.

Motion processing after sight restoration: No competition between visual recovery and auditory compensation.

The present study tested whether or not functional adaptations following congenital blindness are maintained in humans after sight-restoration and whether they interfere with visual recovery. In permanently congenital blind individuals both intramodal plasticity (e.g. changes in auditory cortex) as well as crossmodal plasticity (e.g. an activation of visual cortex by auditory stimuli) have been observed. Both phenomena were hypothesized to contribute to improved auditory functions. For example, it has been shown that early permanently blind individuals outperform sighted controls in auditory motion processing and that auditory motion stimuli elicit activity in typical visual motion areas. Yet it is unknown what happens to these behavioral adaptations and cortical reorganizations when sight is restored, that is, whether compensatory auditory changes are lost and to which degree visual motion processing is reinstalled. Here we employed a combined behavioral-electrophysiological approach in a group of sight-recovery individuals with a history of a transient phase of congenital blindness lasting for several months to several years. They, as well as two control groups, one with visual impairments, one normally sighted, were tested in a visual and an auditory motion discrimination experiment. Task difficulty was manipulated by varying the visual motion coherence and the signal to noise ratio, respectively. The congenital cataract-reversal individuals showed lower performance in the visual global motion task than both control groups. At the same time, they outperformed both control groups in auditory motion processing suggesting that at least some compensatory behavioral adaptation as a consequence of a complete blindness from birth was maintained. Alpha oscillatory activity during the visual task was significantly lower in congenital cataract reversal individuals and they did not show ERPs modulated by visual motion coherence as observed in both control groups. In contrast, beta oscillatory activity in the auditory task, which varied as a function of SNR in all groups, was overall enhanced in congenital cataract reversal individuals. These results suggest that intramodal plasticity elicited by a transient phase of blindness was maintained and might mediate the prevailing auditory processing advantages in congenital cataract reversal individuals. By contrast, auditory and visual motion processing do not seem to compete for the same neural resources. We speculate that incomplete visual recovery is due to impaired neural network turning which seems to depend on early visual input. The present results demonstrate a privilege of the first arriving input for shaping neural circuits mediating both auditory and visual functions.

Quantitative Postural Analysis of Children With Congenital Visual Impairment.

OBJECTIVES: The aim of this study was to compare the postural alignment of children with visual impairment with that of children without visual impairment. METHODS: The sample studied was 74 children of both sexes ages 5 to 12 years. Of these, 34 had visual impairment and 40 were control children. Digital photos from the standing position were used to analyze posture. Postural variables, such as tilt of the head, shoulder position, scapula position, lateral deviation of the spine, ankle position in the frontal plane and head posture, angle of thoracic kyphosis, angle of lumbar lordosis, pelvis position, and knee position in the frontal and sagittal planes, were measured with the Postural Assessment Software 0.63, version 36 (SAPO, São Paulo, Brazil), with markers placed in predetermined bony landmarks. RESULTS: The main results of this study showed that children with visual impairment have increased head tilt (P < .001), shoulder deviation in frontal plane (P = .004), lateral deviation of the spine (P < .001), changes in scapula position (P = .012), higher thoracic kyphosis (P = .004), and lower lumbar lordosis (P < .001). CONCLUSIONS: Visual impairment influences postural alignment. Children with visual impairment had increased head tilt, uneven shoulders, greater lateral deviation of the spine, thoracic kyphosis, lower lumbar lordosis, and more severe valgus deformities on knees.

Frontal EEG asymmetry and later behavior vulnerability in infants with congenital visual impairment.

OBJECTIVE: Young children with congenital visual impairment (VI) are at increased risk of behavioral vulnerabilities. Studies on 'at risk' populations suggest that frontal EEG asymmetry may be associated with behavioral risk. We investigated frontal asymmetry at 1year (Time 1), behavior at 2years (Time 2) and their longitudinal associations within a sample of infants with VI. Frontal asymmetry in the VI sample at 1year was also compared cross-sectionally to an age-matched typically sighted (TS) group. METHODS: At Time 1, 22 infants with VI and 10 TS infants underwent 128-channel EEG recording. Frontal asymmetry ratios were calculated from power spectral density values in the alpha frequency band. At Time 2, Achenbach Child Behavior Checklist data was obtained for the VI sample. RESULTS: 63.6% of the VI sample and 50% of the TS sample showed left frontal asymmetry; no significant difference in frontal asymmetry was found between the two groups. 22.7% of the VI sample had subclinical to clinical range 'internalizing' behavior difficulties. Greater left frontal asymmetry at one year was significantly associated with greater emotionally reactive scores at two years within the VI sample (r=0.50, p=0.02). CONCLUSIONS: Left frontal asymmetry correlates with later behavior risk within this vulnerable population. SIGNIFICANCE: These findings make an important first contribution regarding the utility of frontal EEG asymmetry as a method to investigate risk in infants with VI.

Visual impairment in children with congenital Zika syndrome.

PURPOSE: To describe the visual impairment associated with ocular and neurological abnormalities in a cohort of children with congenital Zika syndrome (CZS). METHODS: This cross-sectional study included infants with microcephaly born in Pernambuco, Brazil, from May to December 2015. Immunoglobulin M antibody capture enzyme-linked immunosorbent assay for the Zika virus on the cerebrospinal fluid samples was positive for all infants. Clinical evaluation consisted of comprehensive ophthalmologic examination including visual acuity, visual function assessment, visual developmental milestone, neurologic examination, and neuroimaging. RESULTS: A total of 32 infants (18 males [56%]) were included. Mean age at examination was 5.7 ± 0.9 months (range, 4-7 months). Visual function and visual developmental milestone could not be tested in 1 child (3%). Visual impairment was detected in 32 infants (100%). Retinal and/or optic nerve findings were observed in 14 patients (44%). There was no statistical difference between the patients with ocular findings and those without (P = 0.180). All patients (100%) demonstrated neurological and neuroimaging abnormalities; 3 (9%) presented with late-onset of microcephaly. CONCLUSIONS: Children with CZS demonstrated visual impairment regardless of retina and/or optic nerve abnormalities. This finding suggests that cortical/cerebral visual impairment may be the most common cause of blindness identified in children with CZS.

Psycho acoustical Measures in Individuals with Congenital Visual Impairment.

INTRODUCTION: In congenital visual impaired individuals one modality is impaired (visual modality) this impairment is compensated by other sensory modalities. There is evidence that visual impaired performed better in different auditory task like localization, auditory memory, verbal memory, auditory attention, and other behavioural tasks when compare to normal sighted individuals. OBJECTIVE: The current study was aimed to compare the temporal resolution, frequency resolution and speech perception in noise ability in individuals with congenital visual impaired and normal sighted. METHODS: Temporal resolution, frequency resolution, and speech perception in noise were measured using MDT, GDT, DDT, SRDT, and SNR50 respectively. Twelve congenital visual impaired participants with age range of 18 to 40 years were taken and equal in number with normal sighted participants. All the participants had normal hearing sensitivity with normal middle ear functioning. RESULTS: Individual with visual impairment showed superior threshold in MDT, SRDT and SNR50 as compared to normal sighted individuals. This may be due to complexity of the tasks; MDT, SRDT and SNR50 are complex tasks than GDT and DDT. CONCLUSION: Visual impairment showed superior performance in auditory processing and speech perception with complex auditory perceptual tasks.

[Ocular electrical stimulation: Therapeutic application and active retinal implants for hereditary retinal degenerations]. / Okuläre elektrische Stimulation : Therapeutische Anwendung und aktive retinale Implantate bei hereditären Netzhautdegenerationen.

BACKGROUND: Electrical stimulation has a long history in ophthalmology. Subthreshold electrical stimulation can have beneficial therapeutic effects on hereditary degenerative retinal diseases. Suprathreshold stimulation is able to elicit visual perceptions and, if multielectrode fields are arranged as an array, usable pictures can be perceived by blind patients. OBJECTIVES: This is a review article on the current situation and studies on therapeutic transcorneal electrical stimulation. Moreover, the challenges, surgical concepts and visual results of active retinal implants are discussed. MATERIAL AND METHODS: This article gives an overview on transcorneal electrical stimulation and active retinal implants based on published results, with special emphasis on the clinical application. RESULTS: The results of initial controlled studies on therapeutic transcorneal electrical stimulation in hereditary retinal diseases were very promising. The largest controlled study so far in patients with retinitis pigmentosa (RP) has yielded many positive trends and some significant improvements in electrophysiological data. Currently, two retinal implants have regulatory approval, the Argus II retinal prosthesis system® (SecondSight®) and the Alpha-IMS© (Retina Implant AG). Both systems can be used to improve visual perception and under test conditions can achieve visual acuities of 0.02 and 0.04, respectively. CONCLUSION: In-depth analyses and follow-up studies in larger patient groups are currently planned to definitively clarify the potential of therapeutic transcorneal electrical stimulation in RP patients. The challenges of currently available active retinal implants are the technical biostability and the limited spatial resolution.

Síndrome de Charles Bonnet secundario a panfotocoagulación retiniana / Charles Bonnet syndrome secondary to panretinal photocoagulation

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Neurooftalmología en la obra de Oliver Sacks: las auras visuales / Neuro-ophthalmology in Oliver Sacks books: Visual auras

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Vaccinium myrtillus / Vaccinium myrtillus

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Congenital Visual Impairment and Progressive Microcephaly Due to Lysyl-Transfer Ribonucleic Acid (RNA) Synthetase (KARS) Mutations: The Expanding Phenotype of Aminoacyl-Transfer RNA Synthetase Mutations in Human Disease.

Aminoacyl-transfer ribonucleic acid (RNA) synthetases (ARSs) are a group of enzymes required for the first step of protein translation. Each aminoacyl-transfer RNA synthetase links a specific amino acid to its corresponding transfer RNA component within the cytoplasm, mitochondria, or both. Mutations in ARSs have been linked to a growing number of diseases. Lysyl-transfer RNA synthetase (KARS) links the amino acid lysine to its cognate transfer RNA. We report 2 siblings with severe infantile visual loss, progressive microcephaly, developmental delay, seizures, and abnormal subcortical white matter. Exome sequencing identified mutations within the KARS gene (NM_005548.2):c.1312C>T; p.Arg438Trp and c.1573G>A; p.Glu525Lys occurring within a highly conserved region of the catalytic domain. Our patients' phenotype is remarkably similar to a phenotype recently reported in glutaminyl-transfer RNA synthetase (QARS), another bifunctional ARS gene. This finding expands the phenotypic spectrum associated with mutations in KARS and draws attention to aminoacyl-transfer RNA synthetase as a group of enzymes that are increasingly being implicated in human disease.