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1.
Sci Rep ; 10(1): 10031, 2020 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-32572106

RESUMO

Down syndrome (DS) is frequently associated with cataract, but there remains scant information about DS cataract morphology. Supra-nuclear cataracts in DS have been proposed as indicative of beta-amyloid (Aß) aggregation and thus potential biomarkers for Alzheimer's (AD). This study employed anterior segment OCT (AS-OCT) and slit-lamp (SL) photography to image the crystalline lens in DS, compared with adult controls. Lens images were obtained post-dilation. Using MATLAB, AS-OCT images were analysed and lens opacities calculated as pixel intensity and area ratios. SL images were classified using LOCS III. Subjects were n = 28 DS (mean ± SD 24.1 ± 14.3years), and n = 36 controls (54.0 ± 3.4years). For the DS group, AS-OCT imaging revealed the frequent presence of small dot opacities (27 eyes, 50%) in the cortex and nucleus of the lens, covering an area ranging from 0.2-14%. There was no relation with age or visual acuity and these dot opacities (p > 0.5) and they were not present in any control lenses. However, their location and morphology does not coincide with previous reports linking these opacities with Aß accumulation and AD. Four participants (14%) in the DS group had clinically significant age-related cataracts, but there was no evidence of early onset of age-related cataracts in DS.

2.
Transl Vis Sci Technol ; 8(5): 8, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31588373

RESUMO

Purpose: It could be argued that current studies investigating smooth pursuit development in children do not provide an optimal measure of smooth pursuit characteristics, given that a significant number have failed to adjust their setup and procedures to the child population. This study aimed to characterize smooth pursuit in children using child-friendly stimuli and procedures. Methods: Eye movements were recorded in 169 children (4-11 years) and 10 adults, while a customized, animated stimulus was presented moving horizontally and vertically at 6°/s and 12°/s. Eye movement recordings from 43 children with delayed reading, two with nystagmus, two with strabismus, and two with unsuccessful calibration were excluded from the analysis. Velocity gain, proportion of smooth pursuit, and the number and amplitude of saccades during smooth pursuit were calculated for the remaining participants. Median and quartiles were calculated for each age group and pursuit condition. ANOVA was used to investigate the effect of age on smooth pursuit parameters. Results: Differences across ages were found in velocity gain (6°/s P < 0.01; 12°/s P < 0.05), as well as the number (12°/s P < 0.05) and amplitude of saccades (12°/s P < 0.05), for horizontal smooth pursuit. Post hoc tests showed that these parameters were different between children aged 7 or younger and adults. No significant differences were found across ages in any smooth pursuit parameter for the vertical direction (P > 0.05). Conclusions: Using child-friendly methods, children over the age of 7 to 8 years demonstrated adultlike smooth pursuit. Translational Relevance: Child-friendly procedures are critical for appropriately characterizing smooth pursuit eye movements in children.

3.
J R Army Med Corps ; 2019 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-31129647

RESUMO

British Armed Forces are facing the most significant recruitment crisis since 2010. An important contributing factor to the recruitment crisis is the rise in obesity of the UK population. At Army Training Centre Pirbright, a weight management programme (WMP) has been established for recruits who have failed their initial medical assessment (IMA). To determine the proportion of recruits who entered the WMP and passed basic and initial trade training, allowing entry into the British Army. Retrospective service evaluation of recruits entering WMP from inception in April 2015 to August 2018. Medical records were used to assess whether recruits completed initial training. 72.3% of recruits included in the WMP who would have previously failed their IMA because of a high body mass index (BMI) passed basic and initial trade training. This evaluation demonstrates potential for candidates otherwise excluded based on BMI. This WMP delivers structured nutritional support and encourages physical training. Once a BMI enters the accepted range, recruits could enter basic training. This WMP would deliver structured nutritional support and encourage physical training, with the aim of promoting healthy lifestyles. Neither the Royal Navy nor the Royal Air Force currently have a WMP. There is potential for WMPs to be introduced to all three services. UK Armed Forces face a recruitment crisis and need to be adaptable with a population where obesity is prevalent. At Pirbright 72.3% of candidates in the WMP passed basic and initial trade training.

5.
Behav Res Methods ; 51(5): 2074-2084, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-30875024

RESUMO

Infantile nystagmus (IN) describes a regular, repetitive movement of the eyes. A characteristic feature of each cycle of the IN eye movement waveform is a period in which the eyes are moving at minimal velocity. This so-called "foveation" period has long been considered the basis for the best vision in individuals with IN. In recent years, the technology for measuring eye movements has improved considerably, but there remains the challenge of calibrating the direction of gaze in tracking systems when the eyes are continuously moving. Identifying portions of the nystagmus waveform suitable for calibration typically involves time-consuming manual selection of the foveation periods from the eye trace. Without an accurate calibration, the exact parameters of the waveform cannot be determined. In this study, we present an automated method for segmenting IN waveforms with the purpose of determining the foveation positions to be used for calibration of an eye tracker. On average, the "point of regard" was found to be within 0.21° of that determined by hand-marking by an expert observer. This method enables rapid clinical quantification of waveforms and the possibility of gaze-contingent research paradigms being performed with this patient group.


Assuntos
Calibragem , Medições dos Movimentos Oculares , Automação , Movimentos Oculares , Humanos , Nistagmo Patológico , Acuidade Visual
6.
PLoS One ; 14(3): e0212733, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30856194

RESUMO

Our objective was to present the findings of an opt-in, school-based eye care service for children attending 11 special schools in England and use these findings to determine whether a vision screening programme would be appropriate for this population. Data from eye examinations provided to 949 pupils (mean age 10.7 years) was analysed to determine the prevalence and aetiology of visual deficiencies and reported eye care history. For 46.2% (n = 438) of pupils, a visual deficiency was recorded. 12.5% of all the children seen (n = 119) had a visual deficiency that was previously undiagnosed. Referral for a medical opinion was made for 3.1% (n = 29) of pupils seen by the service. Spectacle correction was needed for 31.5% (n = 299) of pupils; for 12.9% (122) these were prescribed for the first time. 3.7% (n = 11) of parents/carers of pupils needing spectacles chose not to use the spectacle dispensing service offered in school. Eye care history was available for 847 pupils (89.3%). Of the pupils for whom an eye care history was available, 44% (n = 373) reported no history of any previous eye care and10.7% (n = 91) reported a history of attending a community optical practice/opticians. Only one pupil from the school entry 4-5 age group (0.6% of age group n = 156) would have passed vision screening using current Public Health England screening guidelines. Children with a diagnosis of autism were significantly less likely to be able to provide a reliable measurement of visual acuity. This study supports previously published evidence of a very high prevalence of visual problems in children with the most complex needs and a significant unmet need in this group. It demonstrates routine school entry vision screening using current Public Health England guidelines is not appropriate for this group of children and very low uptake of community primary eye care services.


Assuntos
Instituições Acadêmicas , Transtornos da Visão , Seleção Visual , Acuidade Visual , Criança , Pré-Escolar , Inglaterra/epidemiologia , Óculos , Feminino , Humanos , Masculino , Prevalência , Transtornos da Visão/diagnóstico , Transtornos da Visão/epidemiologia
7.
J R Army Med Corps ; 165(5): 346-350, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29735488

RESUMO

Exercise ASKARI SERPENT (Ex AS) is an annual British Army medical exercise that sees the deployment of a medical regiment to rural Kenya. The exercise involves the delivery of health outreach clinics and health education to the civilian population alongside Kenyan governmental and non-governmental organisations. This article includes a post hoc analysis of the ethical and clinical challenges that clinicians faced during Ex AS, applying a four-quadrant approach to ethical decision-making. This article intends to stimulate further debate and discussion on how to best prepare clinicians for clinical challenges and ethical decision-making on future exercises and operations. We conclude that our experiences on Ex AS can provide an insight on how to develop predeployment training for clinicians. Furthermore, the universal nature of the challenges faced on Ex AS can be applied to training for future contingency operations.


Assuntos
Tomada de Decisões/ética , Ética Médica , Medicina Militar/ética , Adolescente , Adulto , Criança , Pré-Escolar , Humanos , Lactente , Quênia , Militares , Reino Unido
8.
Urolithiasis ; 47(4): 383-390, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29959479

RESUMO

INTRODUCTION: Complex ureteric strictures present a significant challenge to the endourologist and uro-radiologist. Multiple separate interventions to try to cross the stricture are often attempted. We describe our experience managing a heterogenous patient group using the 'rendezvous' procedure. METHODS AND MATERIALS: 16 patients and 18 ureters (one bilateral procedure, and two separate procedures in one patient) underwent rendezvous procedures. Seven patients had coexisting ureteric calculi treated. Each case was followed up for between 3 months and 5 years. RESULTS: In 16/18 ureters there was technical success at time of surgery; successfully crossing the stricture, allowing ureteroscopic access to the ureter, dilating and/or stenting the ureter. 2/18 were unsuccessful; one secondary to advanced malignancy resulting in a uretero-vaginal fistula and the second a failure to remove a retained, displaced ureteric stent. Of the 18 ureteric procedures; 7/18 were stent free at 3 months, improving to 8/18 stent free at 6 months. 4/18 remained nephrostomy dependent (failure of drainage despite stent or failure to stent) at 3 months, increasing to 6/18 being nephrostomy dependent at 6 months. 1/16 remained dialysis dependent with a nephrostomy tube. For those procedures involving ureteric calculi, 6/7 were stone free and 1/5 had a persistent stone fragment requiring further intervention. CONCLUSIONS: A combined approach may decrease the number of separate interventions required, with the aim of removing the need for a long-term nephrostomy, as well as providing opportunity to treat ureteric calculi in the context of stricture disease. Our experience has been that where the rendezvous has been required to treat strictures caused by malignant extrinsic compression, stenting has not been successful; this information is key to informed consent in a group of patients who may have a limited life expectancy.


Assuntos
Ureter/cirurgia , Cálculos Ureterais/cirurgia , Obstrução Ureteral/cirurgia , Ureteroscopia/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Constrição Patológica/etiologia , Constrição Patológica/cirurgia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Resultado do Tratamento , Ureter/patologia , Cálculos Ureterais/complicações , Obstrução Ureteral/etiologia
9.
Sci Rep ; 8(1): 3858, 2018 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-29497120

RESUMO

Ricco's area (the largest area of visual space in which stimulus area and intensity are inversely proportional at threshold) has previously been hypothesised to be a result of centre/surround antagonism in retinal ganglion cell receptive fields, but recent evidence suggests a sizeable cortical contribution. Here, Ricco's area was measured in amblyopia, a condition in which retinal receptive fields are normal, to better understand its physiological basis. Spatial summation functions were determined at 12 visual field locations in both eyes of 14 amblyopic adults and 15 normal-sighted controls. Ricco's area was significantly larger in amblyopic eyes than in fellow non-amblyopic eyes. Compared to the size of Ricco's area in control eyes, Ricco's area measured significantly larger in amblyopic eyes. Additionally, Ricco's area in the fellow, non-amblyopic eye of amblyopic participants measured significantly smaller than in control eyes. Compared to controls, Ricco's area was larger in amblyopic eyes and smaller in fellow non-amblyopic eyes. Amblyopia type, binocularity, and inter-ocular difference in visual acuity were significantly associated with inter-ocular differences in Ricco's area in amblyopes. The physiological basis for Ricco's area is unlikely to be confined to the retina, but more likely representative of spatial summation at multiple sites along the visual pathway.


Assuntos
Ambliopia/fisiopatologia , Estrabismo/fisiopatologia , Campos Visuais/fisiologia , Adulto , Anisometropia/complicações , Feminino , Humanos , Masculino , Erros de Refração/complicações , Retina/fisiopatologia , Células Ganglionares da Retina/fisiologia , Visão Ocular/fisiologia , Acuidade Visual/fisiologia , Vias Visuais/fisiopatologia
10.
Clin Exp Optom ; 101(4): 535-540, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29601092

RESUMO

BACKGROUND: Visual acuity is known to be poorer in children with Down's syndrome than in age-matched controls. However, to date, clinicians do not have access to norms for children with Down's syndrome that allow differential discrimination of healthy from anomalous visual development in this population. METHODS: The Down's Syndrome Vision Research Unit at Cardiff University has been monitoring visual development in a large cohort of children since 1992. Cross-sectional data on binocular visual acuity were retrospectively analysed for 159 children up to 12 years of age in order to establish binocular acuity norms. Longitudinal binocular acuity data were available for nine children who were seen regularly over the 12 years age-range. Monocular acuity was successfully recorded less often in the cohort, but analysis of scores for 69 children allowed assessment of inter-ocular acuity differences and binocular summation. RESULTS: In comparison with published norms for the various acuity tests used, binocular acuity was consistently poorer in children with Down's syndrome from the age of three years and stabilised at around 0.25 logMAR from the age of four years. Inter-ocular acuity difference and binocular summation were both 0.06 logMAR, which is similar to the reported values in children without Down's syndrome. CONCLUSIONS: The study provides eye-care practitioners with the expected values for binocular acuity in children with Down's syndrome and demonstrates the visual disadvantage that children with Down's syndrome have when compared with their typically developing peers. The results emphasise the responsibility that practitioners have to notify parents and educators of the relatively poor vision of children with Down's syndrome, and the need for classroom modifications.


Assuntos
Síndrome de Down/fisiopatologia , Valores de Referência , Transtornos da Visão/fisiopatologia , Visão Binocular/fisiologia , Acuidade Visual/fisiologia , Criança , Pré-Escolar , Estudos Transversais , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Estudos Retrospectivos
11.
Ophthalmic Physiol Opt ; 37(4): 531-541, 2017 07.
Artigo em Inglês | MEDLINE | ID: mdl-28656674

RESUMO

PURPOSE: Previous studies have reported that eye movements differ between good/average and poor readers. However, these studies have been limited to investigating eye movements during reading related tasks, and thus, the differences found could arise from deficits in higher cognitive processes involved in reading rather than oculomotor performance. The purpose of the study is to determine the extent to which eye movements in children with delayed reading skills are different to those obtained from children with good/average reading skills in non-reading related tasks. METHODS: After a screening optometric assessment, eye movement recordings were obtained from 120 children without delayed reading skills and 43 children with delayed reading skills (4 to 11 years) using a Tobii TX300 eye tracker. Cartoon characters were presented horizontally from -20° to +20° in steps of 5° to study saccades. An animated stimulus in the centre of the screen was presented for 8 seconds to study fixation stability. Saccadic main sequences, and the number and amplitude of the saccades during fixation were obtained for each participant. Children with delayed reading skills (n = 43) were unmasked after data collection was completed. Medians and quartiles were calculated for each eye movement parameter for children without (n = 120) and with (n = 43) delayed reading skills. RESULTS: Independent t-tests with Bonferroni correction showed no significant differences in any of the saccadic main sequence parameters (Slope, Intercept, A, n and Q ratio) between children without and with delayed reading (p > 0.01). Similarly, no significant differences were found in the number of saccades and their amplitude during the fixation task between the two groups (p > 0.05). Further, none of the gross optometric parameters assessed (visual acuity, refractive error, ocular alignment, convergence, stereopsis and accommodation accuracy) were found to be associated with delayed reading skills (p > 0.05). CONCLUSIONS: Eye movements in children with delayed reading skills are quantitatively similar to those found in children without delayed reading skills. These findings suggest that, in these children, delayed reading skills are not associated with eye movements and further question interventions targeted at improving eye movement control.


Assuntos
Acomodação Ocular , Percepção de Profundidade/fisiologia , Fixação Ocular/fisiologia , Leitura , Erros de Refração/fisiopatologia , Movimentos Sacádicos/fisiologia , Visão Binocular/fisiologia , Criança , Pré-Escolar , Feminino , Humanos , Masculino , Acuidade Visual
12.
Optom Vis Sci ; 94(7): 760-769, 2017 07.
Artigo em Inglês | MEDLINE | ID: mdl-28609416

RESUMO

PURPOSE: This study presents a two-degree customized animated stimulus developed to evaluate smooth pursuit in children and investigates the effect of its predetermined characteristics (stimulus type and size) in an adult population. Then, the animated stimulus is used to evaluate the impact of different pursuit motion paradigms in children. METHODS: To study the effect of animating a stimulus, eye movement recordings were obtained from 20 young adults while the customized animated stimulus and a standard dot stimulus were presented moving horizontally at a constant velocity. To study the effect of using a larger stimulus size, eye movement recordings were obtained from 10 young adults while presenting a standard dot stimulus of different size (1° and 2°) moving horizontally at a constant velocity. Finally, eye movement recordings were obtained from 12 children while the 2° customized animated stimulus was presented after three different smooth pursuit motion paradigms. Performance parameters, including gains and number of saccades, were calculated for each stimulus condition. RESULTS: The animated stimulus produced in young adults significantly higher velocity gain (mean: 0.93; 95% CI: 0.90-0.96; P = .014), position gain (0.93; 0.85-1; P = .025), proportion of smooth pursuit (0.94; 0.91-0.96, P = .002), and fewer saccades (5.30; 3.64-6.96, P = .008) than a standard dot (velocity gain: 0.87; 0.82-0.92; position gain: 0.82; 0.72-0.92; proportion smooth pursuit: 0.87; 0.83-0.90; number of saccades: 7.75; 5.30-10.46). In contrast, changing the size of a standard dot stimulus from 1° to 2° did not have an effect on smooth pursuit in young adults (P > .05). Finally, smooth pursuit performance did not significantly differ in children for the different motion paradigms when using the animated stimulus (P > .05). CONCLUSIONS: Attention-grabbing and more dynamic stimuli, such as the developed animated stimulus, might potentially be useful for eye movement research. Finally, with such stimuli, children perform equally well irrespective of the motion paradigm used.


Assuntos
Movimentos Oculares/fisiologia , Percepção de Movimento/fisiologia , Acompanhamento Ocular Uniforme/fisiologia , Adolescente , Adulto , Criança , Pré-Escolar , Feminino , Generalização do Estímulo , Humanos , Masculino , Movimentos Sacádicos , Adulto Jovem
13.
Invest Ophthalmol Vis Sci ; 58(1): 642-650, 2017 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-28129427

RESUMO

Purpose: Most individuals with infantile nystagmus (IN) have an idiosyncratic gaze angle at which their nystagmus intensity is minimized. Some adopt an abnormal head posture to use this "null zone," and it has therefore long been assumed that this provides people with nystagmus with improved visual acuity (VA). However, recent studies suggest that improving the nystagmus waveform could have little, if any, influence on VA; that is, VA is fundamentally limited in IN. Here, we examined the impact of the null zone on VA. Methods: Visual acuity was measured in eight adults with IN using a psychophysical staircase procedure with reversals at three horizontal gaze angles, including the null zone. Results: As expected, changes in gaze angle affected nystagmus amplitude, frequency, foveation duration, and variability of intercycle foveation position. Across participants, each parameter (except frequency) was significantly correlated with VA. Within any given individual, there was a small but significant improvement in VA (0.08 logMAR) at the null zone as compared with the other gaze angles tested. Despite this, no change in any of the nystagmus waveform parameters was significantly associated with changes in VA within individuals. Conclusions: A strong relationship between VA and nystagmus characteristics exists between individuals with IN. Although significant, the improvement in VA observed within individuals at the null zone is much smaller than might be expected from the occasionally large variations in intensity and foveation dynamics (and anecdotal patient reports of improved vision), suggesting that improvement of other aspects of visual performance may also encourage use of the null zone.


Assuntos
Adaptação Ocular/fisiologia , Movimentos Oculares/fisiologia , Nistagmo Congênito/fisiopatologia , Músculos Oculomotores/fisiopatologia , Acuidade Visual/fisiologia , Adulto , Técnicas de Diagnóstico Oftalmológico , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Nistagmo Congênito/diagnóstico , Músculos Oculomotores/diagnóstico por imagem , Postura , Adulto Jovem
14.
Clin Optom (Auckl) ; 9: 123-131, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-30214368

RESUMO

Infantile nystagmus (IN), previously known as congenital nystagmus, is an involuntary to-and-fro movement of the eyes that persists throughout life. IN is one of three types of early-onset nystagmus that begin in infancy, alongside fusion maldevelopment nystagmus syndrome and spasmus nutans syndrome. Optometrists may also encounter patients with acquired nystagmus. The features of IN overlap largely with those of fusion maldevelopment nystagmus syndrome, spasmus nutans syndrome, and acquired nystagmus, yet the management for each subtype is different. Therefore, the optometrist's role is to accurately discern IN from other forms of nystagmus and to manage accordingly. As IN is a lifelong condition, its presence not only affects the visual function of the individual but also their quality of life, both socially and psychologically. In this report, we focus on the approaches that involve optometrists in the investigation and management of patients with IN. Management includes the prescription of optical treatments, low-vision rehabilitation, and other interventions such as encouraging the use of the null zone and referral to support groups. Other treatments available via ophthalmologists are also briefly discussed in the article.

15.
Clin J Sport Med ; 26(2): 133-8, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26192375

RESUMO

OBJECTIVE: To describe visual problems among athletes with intellectual disabilities (IDs) and the role of vision in special sports. DESIGN: A cross-sectional observational study. SETTING: Athletes participating in Special Olympics European Summer Games 2010 in Warsaw attended vision screening by Special Olympics Lions Clubs International Opening Eyes. PARTICIPANTS: Coaches were encouraged to bring all athletes to screening without selection; 900 athletes from 52 European countries participated. INTERVENTIONS: Standard noninvasive eye examination procedures. Independent variables were age, gender, sport, and country of origin. MAIN OUTCOME MEASURES: Eyeglasses wear, presenting visual acuity, refractive error, and ocular health. RESULTS: Testability rates were very high. Findings confirmed high prevalence of ocular/visual defects in people with ID. There was an association between acuity and sport discipline. Few athletes used sports glasses. Screening revealed a lack of eye care even in the most developed nations. CONCLUSIONS: The impact of vision on sports activity in athletes with ID is significant. More needs to be done to ensure good vision and safety correction for active people with ID. Better provision and greater awareness of eye care in people with ID is needed in all European societies. CLINICAL RELEVANCE: Data presented highlight the need for increased awareness of the role of vision in sporting achievements, personal development, and quality of life in active people with ID. Athletes with ID should have easily accessible comprehensive eye care, and when appropriate, corrective and protective glasses. This will require the efficient cooperation of vision specialists, coaches, carers, and athletes themselves.


Assuntos
Atletas/estatística & dados numéricos , Pessoas com Deficiência/estatística & dados numéricos , Transtornos da Visão/epidemiologia , Adolescente , Adulto , Criança , Estudos Transversais , Óculos/estatística & dados numéricos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Erros de Refração , Acuidade Visual , Adulto Jovem
16.
Philos Trans A Math Phys Eng Sci ; 373(2051)2015 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-26303925

RESUMO

Nonlinear behaviour is ever-present in vibrations and other dynamical motions of engineering structures. Manifestations of nonlinearity include amplitude-dependent natural frequencies, buzz, squeak and rattle, self-excited oscillation and non-repeatability. This article primarily serves as an extended introduction to a theme issue in which such nonlinear phenomena are highlighted through diverse case studies. More ambitiously though, there is another goal. Both the engineering context and the mathematical techniques that can be used to identify, analyse, control or exploit these phenomena in practice are placed in the context of a mind-map, which has been created through expert elicitation. This map, which is available in software through the electronic supplementary material, attempts to provide a practitioner's guide to what hitherto might seem like a vast and complex research landscape.

17.
Invest Ophthalmol Vis Sci ; 56(9): 5094-101, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26241396

RESUMO

PURPOSE: Treatments for infantile nystagmus (IN) sometimes elicit subjective reports of improved visual function, yet quantifiable improvements in visual acuity, if any, are often negligible. One possibility is that these subjective "improvements" may relate to temporal, rather than spatial, visual function. This study aimed to ascertain the extent to which "time to see" might be increased in nystagmats, as compared to normally sighted controls. By assessing both eye movement and response time data, it was possible to determine whether delays in "time to see" were due solely to the eye movements, or to an underlying deficit in visual processing. METHODS: The time taken to respond to the orientation of centrally and peripherally presented gratings was measured in subjects with IN and normally sighted controls (both groups: n = 11). For each vertically displaced grating, the time until the target-acquiring saccade was determined, as was the time from the saccade until the subject's response. RESULTS: Nystagmats took approximately 60 ms longer than controls to execute target-acquiring saccades to vertically displaced targets (P = 0.010). However, the time from the end of the saccade until subjects responded was not significantly different between groups (P = 0.37). Despite this, nystagmats took longer to respond to gratings presented at fixation. CONCLUSIONS: Individuals with IN took longer to direct their gaze toward objects of interest. However, once a target was foveated, the time taken to process visual information and respond did not appear to differ from that of control subjects. Therefore, conscious visual processing in IN is not slow.


Assuntos
Nistagmo Congênito/fisiopatologia , Orientação , Tempo de Reação/fisiologia , Movimentos Sacádicos/fisiologia , Acuidade Visual , Percepção Visual/fisiologia , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
19.
Invest Ophthalmol Vis Sci ; 55(4): 2682-6, 2014 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-24651552

RESUMO

PURPOSE: Infantile nystagmus (IN) consists of largely horizontal oscillations of the eyes that usually begin shortly after birth. The condition is almost always associated with lower-than-normal visual acuity (VA). This is assumed to be at least partially due to motion blur induced by the eye movements. Here, we investigated the effect of image motion on VA. METHODS: Grating stimuli were presented, illuminated by either multiple tachistoscopic flashes (0.76 ms) to circumvent retinal image motion, or under constant illumination, to subjects with horizontal idiopathic IN and controls. A staircase procedure was used to estimate VA (by judging direction of tilt) under each condition. Orientation-specific effects were investigated by testing gratings oriented about both the horizontal and vertical axes. RESULTS: Nystagmats had poorer VA than controls under both constant and tachistoscopic illumination. Neither group showed a significant difference in VA between illumination conditions. Nystagmats performed worse for vertically oriented gratings, even under tachistoscopic conditions (P < 0.01), but there was no significant effect of orientation in controls. CONCLUSIONS: The fact that VA was not significantly affected by either illumination condition strongly suggests that the eye movements themselves do not significantly degrade VA in adults with IN. Treatments and therapies that seek to modify and/or reduce eye movements may therefore be fundamentally limited in any improvement that can be achieved with respect to VA.


Assuntos
Movimentos Oculares/fisiologia , Movimento (Física) , Nistagmo Congênito/fisiopatologia , Acuidade Visual , Adulto , Idoso , Potenciais Evocados Visuais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Oftalmoscopia , Estimulação Luminosa , Adulto Jovem
20.
Br J Ophthalmol ; 98(1): 6-12, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24158842

RESUMO

Children with visual impairment and a condition affecting their neurodevelopment (children with VND) may require extensive and specialised help but evidence on the most effective strategies for visual improvement is lacking. We defined a PICO format (Population, Intervention, Comparator, Outcome) for a scoping review and systematically searched 13 databases. Two reviewers assessed the abstracts for inclusion and a third arbitrated in cases of disagreement. We abstracted data from included studies. We found 4450 abstracts from which we identified 107 papers for inclusion. Of these, 42 related to interventions involving a change in visual input or function: 5 controlled trials, 8 before and after studies and 29 case reports. The strongest evidence supported the provision of spectacles to improve distance or near vision and the use of ultraviolet light as environmental modification for training. Less strong but suggestive evidence supported training/practice routines to improve acuity or oculomotor control. Interventions exist to help children with VND and current recommendations that they are assessed by a vision specialist are supported by the evidence. More information is needed on the effectiveness of training/practice programmes which may promote improved function, and of environmental modifications to facilitate engagement of children with VND with the surroundings.


Assuntos
Deficiências do Desenvolvimento/complicações , Doenças do Sistema Nervoso/complicações , Transtornos da Visão/terapia , Humanos , Transtornos da Visão/etiologia , Transtornos da Visão/reabilitação
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