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1.
Am J Ophthalmol ; 2021 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-34699740

RESUMO

PURPOSE: To assess test-retest repeatability of the accommodative response (AR) in children with and without amblyopia and adults using the Grand Seiko autorefractor. DESIGN: Prospective Reliability Assessment METHODS: Test-retest of accommodation was obtained while participants viewed 20/150 sized letters at 33 cm using the Grand Seiko autorefractor of children 5 to < 11 years with amblyopia (n=24) and without amblyopia (n=36), and adults 18 to < 35 years (n=34). Bland-Altman 95% limits of agreement (LOA) and intraclass correlation coefficients (ICC) were used to assess repeatability and reliability. The AR between the fellow and amblyopic eyes of children with amblyopia and Eye 1 and Eye 2 of the visually normal participants was assessed using group comparisons. RESULTS: The 95% LOA of the AR was greatest in the amblyopic eyes (-1.25 D, 1.62 D) of children with amblyopia. The 95% LOA were similar between the fellow eyes (-0.88 D, 0.74 D) of children with amblyopia and both eyes of the children without amblyopia (Eye 1: -0.68 D, 0.71 D; Eye 2: -0.59 D, 0.70 D) and the adults (Eye 1: 95% LOA = -0.49 D to 0.45 D; Eye 2: LOA = -0.66 D to 0.67 D). ICC revealed the Grand Seiko autorefractor as a reliable instrument for measuring AR. CONCLUSIONS: The Grand Seiko autorefractor was more repeatable and reliable when measuring the AR in children and adults without amblyopia than in the amblyopic eye in children with amblyopia. It is recommended that multiple measures of the AR is obtained in amblyopic eyes to improve the precision of measures.

2.
Brain Inj ; 35(10): 1218-1228, 2021 08 24.
Artigo em Inglês | MEDLINE | ID: mdl-34383619

RESUMO

PURPOSE: To examine the association between Post-Concussion Symptom Scale (PCSS) scores, Convergence Insufficiency Symptom Survey (CISS) scores, and oculomotor deficits post-concussion. METHODS: Records of adolescent patients examined in a multidisciplinary concussion clinic between July 2014 and May 2019 were reviewed. PCSS and CISS scores, results of eye examination and oculomotor assessment, concussion history, and demographics were abstracted. RESULTS: One hundred and forty patient records (median age, 15.3 years; 52 males, presented 109 days (median) from their most recent concussion) met inclusion criteria. Mean total scores on PCSS and CISS were 46.67 ± 25.89 and 27.13 ± 13.22, respectively, and were moderately correlated with each other (r = 0.53, p < .001). Oculomotor deficits were observed in 123 (88%) patients. Step-wise linear regression identified increased PCSS total score to be significantly associated with decreased amplitude of accommodation (p < .001). Increased CISS total score was significantly associated with receded near point of convergence, developmental eye movement test error scores, and cause of concussion. CONCLUSION: High PCSS scores may indicate an accommodation deficit and thus prompt an oculomotor assessment in patients following a concussion. Using the CISS and a detailed oculomotor assessment may reveal underlying oculomotor deficits, which may benefit from treatment.


Assuntos
Traumatismos em Atletas , Concussão Encefálica , Síndrome Pós-Concussão , Adolescente , Concussão Encefálica/complicações , Movimentos Oculares , Humanos , Masculino , Testes Neuropsicológicos , Síndrome Pós-Concussão/diagnóstico , Síndrome Pós-Concussão/epidemiologia
3.
Vision Res ; 184: 30-36, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33838503

RESUMO

Many patients with concussion experience visual symptoms following injury that lead to a diagnosis of convergence insufficiency, accommodative insufficiency, or saccadic dysfunction. However, these diagnostic categories are based on aggregates of clinical tests developed from a non-concussed population and therefore may not accurately describe visual deficits in the concussed population. Thus, we sought to understand individual metrics of visual dysfunction in chronically symptomatic post-concussion patients. This retrospective cross-sectional study included patients examined at the multidisciplinary concussion clinic (MDCC) at Boston Children's Hospital over four years. Patients aged 5-21 years who had a complete assessment of eye alignment, vergence, accommodation, and visual tracking, and had visual acuity better than or equal to 20/30 in each eye were included. Patients with history of amblyopia, strabismus, or ocular pathology were excluded. Chart review yielded 116 patients who met inclusion criteria (median age 15 years, 64% female). The majority of patients (52%) experienced a single concussion and most were sports-related (50%). Clinical data show vergence, accommodation, or visual tracking deficits in 95% of patients. A receded near point of convergence (NPC, 70/116) and reduced accommodative amplitude (63/116) were the most common deficits. Both NPC and accommodative amplitude were significantly correlated with one another (r = -0.5) and with measures of visual tracking (r = -0.34). Patients with chronic post-concussion symptoms show deficits in individual metrics of vergence, accommodation and visual tracking. The high incidence of these deficits, specifically NPC and accommodative amplitude, highlights the need for a detailed sensorimotor evaluation to guide personalized treatment following concussion.

4.
Clin J Sport Med ; 2021 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-33605602

RESUMO

OBJECTIVE: To describe the collaborative findings across a broad array of subspecialties in children and adolescents with postconcussion syndrome (PCS) in a pediatric multidisciplinary concussion clinic (MDCC) setting. DESIGN: Retrospective analysis. SETTING: Multidisciplinary concussion clinic at a pediatric tertiary-level hospital. PATIENTS: Fifty-seven patients seen in MDCC for evaluation and management of PCS between June 2014 and January 2016. INTERVENTIONS: Clinical evaluation by neurology, sports medicine, otolaryngology, optometry, ophthalmology, physical therapy, and psychology. MAIN OUTCOME MEASURES: Specialty-specific clinical findings and specific, treatable diagnoses relevant to PCS symptoms. RESULTS: A wide variety of treatable, specialty-specific diagnoses were identified as potential contributing factors to patients' postconcussion symptoms. The most common treatable diagnoses included binocular vision dysfunction (76%), anxiety, (57.7%), depression (44.2%), new or change in refractive error (21.7%), myofascial pain syndrome (19.2%), and benign paroxysmal positional vertigo (17.5%). CONCLUSIONS: Patients seen in a MDCC setting receive a high number of treatable diagnoses that are potentially related to patients' PCS symptoms. The MDCC approach may (1) increase access to interventions for PCS-related impairments, such as visual rehabilitation, physical therapy, and psychological counseling; (2) provide patients with coordinated medical care across specialties; and (3) hasten recovery from PCS.

6.
Am J Ophthalmol ; 206: 235-244, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31004592

RESUMO

PURPOSE: To determine the frequency of occurrence of receded near point of convergence (NPC) in patients with chronic concussion-related symptoms and in those with receded NPC to enumerate the frequency of convergence insufficiency and other oculomotor disorders. DESIGN: Retrospective cross-sectional study. METHODS: Clinic charts were retrospectively reviewed for the prior 3.5 years to identify all patients < 21 years old who were > 28 days postconcussion, had chronic concussion-related symptoms, had normal visual acuity, and had received a comprehensive sensorimotor examination. The frequency of receded NPC and oculomotor diagnoses were determined. RESULTS: Of the 83 eligible patients, 74 (89%) had receded NPC. Of these, 70 (95%) had oculomotor disorders; 30 (41%) had disorders of accommodation only; 21 (28%) had convergence insufficiency and accommodation deficits; and 6 (8%) had convergence insufficiency only. Six (8%) had a convergence deficit other than convergence insufficiency (all with concurrent accommodative disorders); 4 (5%) had both a nonspecific vergence dysfunction and accommodation deficits; 2 (3%) had convergence excess only; and 1 (1%) had both convergence excess and accommodative deficits. CONCLUSION: A receded NPC was present in the majority of young patients with chronic postconcussion symptoms. Associated with numerous underlying oculomotor dysfunctions, the clinical finding of a receded NPC is not synonymous with the diagnosis of convergence insufficiency. Because treatment options for the various oculomotor dysfunctions differ, it is prudent that these patients undergo a thorough examination of their vergence and accommodative systems so that an accurate diagnosis can be made and appropriate treatment prescribed.


Assuntos
Acomodação Ocular/fisiologia , Concussão Encefálica/complicações , Convergência Ocular/fisiologia , Transtornos da Motilidade Ocular/etiologia , Transtornos da Motilidade Ocular/fisiopatologia , Músculos Oculomotores/fisiopatologia , Visão Binocular/fisiologia , Adolescente , Concussão Encefálica/fisiopatologia , Estudos Transversais , Feminino , Humanos , Masculino , Estudos Retrospectivos
7.
Vision Res ; 155: 11-16, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30528188

RESUMO

Although there are many anecdotal reports of children with developmental dyslexia complaining of vision symptoms when reading, empirical studies are lacking. The primary aim of the present study was to document self-reported vision-related symptoms in children with developmental dyslexia and typically reading peers. We also explored whether vision symptoms were correlated with sensorimotor measures of vergence, accommodation and ocular motor tracking skills. Using a prospective group comparison observational design, we assessed 28 children with developmental dyslexia (DD) and 33 typically reading children (TR) 7-11 years of age. Participants completed psychoeducational testing, a comprehensive sensorimotor eye examination, and the Convergence Insufficiency Symptom Survey (CISS), which includes 9 items pertaining to vision-related symptoms (CISS-V) and 6 that could have cognitive influence (CISS-C). CISS-V were significantly greater in DD than TR children. Ocular motor tracking, assessed by an infra-red limbal eye tracker while reading text, was most clearly associated with the visual symptoms, but only within the DD group. Vision-related symptom surveys followed by a comprehensive eye examination with detailed evaluation of sensorimotor functioning for those who report a high prevalence of symptoms may be clinically relevant for children with DD.


Assuntos
Convergência Ocular/fisiologia , Dislexia/complicações , Transtornos da Motilidade Ocular/etiologia , Transtornos da Motilidade Ocular/fisiopatologia , Transtornos da Visão/etiologia , Criança , Autoavaliação Diagnóstica , Feminino , Humanos , Masculino , Estudos Prospectivos , Autorrelato , Transtornos da Visão/fisiopatologia
8.
Ophthalmology ; 126(3): 456-466, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30352226

RESUMO

PURPOSE: To compare visual acuity (VA) improvement in children aged 7 to 12 years with amblyopia treated with a binocular iPad game plus continued spectacle correction vs. continued spectacle correction alone. DESIGN: Multicenter randomized clinical trial. PARTICIPANTS: One hundred thirty-eight participants aged 7 to 12 years with amblyopia (33-72 letters, i.e., approximately 20/200 to 20/40) resulting from strabismus, anisometropia, or both. Participants were required to have at least 16 weeks of optical treatment in spectacles if needed or demonstrate no improvement in amblyopic-eye visual acuity (VA) for at least 8 weeks prior to enrollment. METHODS: Eligible participants (mean age 9.6 years, mean baseline VA of 59.6 letters, history of prior amblyopia treatment other than spectacles in 96%) were randomly assigned to treatment for 8 weeks with the dichoptic binocular Dig Rush iPad game (prescribed for 1 hour per day 5 days per week) plus spectacle wear if needed (n = 69) or continued spectacle correction alone if needed (n = 69). MAIN OUTCOME MEASURES: Change in amblyopic-eye VA from baseline to 4 weeks, assessed by a masked examiner. RESULTS: At 4 weeks, mean amblyopic-eye VA letter score improved from baseline by 1.3 (2-sided 95% confidence interval [CI]: 0.1-2.6; 0.026 logMAR) with binocular treatment and by 1.7 (2-sided 95% CI: 0.4-3.0; 0.034 logMAR) with continued spectacle correction alone. After adjusment for baseline VA, the letter score difference between groups (binocular minus control) was -0.3 (95% CI: -2.2 to 1.5, P = 0.71, difference of -0.006 logMAR). No difference in letter scores was observed between groups when the analysis was repeated after 8 weeks of treatment (adjusted mean: -0.1, 98.3% CI: -2.4 to 2.1). For the binocular group, adherence data from the iPad indicated that slightly more than half of the participants (58% and 56%) completed >75% of prescribed treatment by the 4- and 8-week visits, respectively. CONCLUSIONS: In children aged 7 to 12 years who have received previous treatment for amblyopia other than spectacles, there was no benefit to VA or stereoacuity from 4 or 8 weeks of treatment with the dichoptic binocular Dig Rush iPad game.


Assuntos
Ambliopia/terapia , Jogos de Vídeo , Visão Binocular/fisiologia , Acuidade Visual/fisiologia , Ambliopia/etiologia , Ambliopia/fisiopatologia , Anisometropia/complicações , Criança , Computadores de Mão , Óculos , Feminino , Seguimentos , Humanos , Masculino , Estrabismo/complicações , Resultado do Tratamento
9.
JAMA Ophthalmol ; 136(10): 1089-1095, 2018 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-30027208

RESUMO

Importance: Developmental dyslexia (DD) is a specific learning disability of neurobiological origin whose core cognitive deficit is widely believed to involve language (phonological) processing. Although reading is also a visual task, the potential role of vision in DD has been controversial, and little is known about the integrity of visual function in individuals with DD. Objective: To assess the frequency of visual deficits (specifically vergence, accommodation, and ocular motor tracking) in children with DD compared with a control group of typically developing readers. Design, Setting, and Participants: A prospective, uncontrolled observational study was conducted from May 28 to October 17, 2016, in an outpatient ophthalmology ambulatory clinic among 29 children with DD and 33 typically developing (TD) children. Main Outcomes and Measures: Primary outcomes were frequencies of deficits in vergence (amplitude, fusional ranges, and facility), accommodation (amplitude, facility, and accuracy), and ocular motor tracking (Developmental Eye Movement test and Visagraph eye tracker). Results: Among the children with DD (10 girls and 19 boys; mean [SD] age, 10.3 [1.2] years) and the TD group (21 girls and 12 boys; mean [SD] age, 9.4 [1.4] years), accommodation deficits were more frequent in the DD group than the TD group (16 [55%] vs 3 [9%]; difference = 46%; 95% CI, 25%-67%; P < .001). For ocular motor tracking, 18 children in the DD group (62%) had scores in the impaired range (in the Developmental Eye Movement test, Visagraph, or both) vs 5 children in the TD group (15%) (difference, 47%; 95% CI, 25%-69%; P < .001). Vergence deficits occurred in 10 children in the DD group (34%) and 5 children in the TD group (15%) (difference, 19%; 95% CI, -2.2% to 41%; P = .08). In all, 23 children in the DD group (79%) and 11 children in the TD group (33%) had deficits in 1 or more domain of visual function (difference, 46%; 95% CI, 23%-69%; P < .001). Conclusions and Relevance: These findings suggest that deficits in visual function are far more prevalent in school-aged children with DD than in TD readers, but the possible cause and clinical relevance of these deficits are uncertain. Further study is needed to determine the extent to which treating these deficits can improve visual symptoms and/or reading parameters.


Assuntos
Dislexia/epidemiologia , Leitura , Transtornos da Visão/epidemiologia , Acomodação Ocular/fisiologia , Criança , Convergência Ocular/fisiologia , Feminino , Humanos , Masculino , Transtornos da Motilidade Ocular/epidemiologia , Estudos Prospectivos , Testes Visuais
10.
Clin J Sport Med ; 28(3): 262-267, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-28742610

RESUMO

OBJECTIVE: To prospectively examine gait characteristics of participants acutely after concussion with and without receded near point of convergence (NPC), compared with healthy controls. DESIGN: Cross-sectional study. SETTING: Sports-medicine clinic. PARTICIPANTS: Patients examined after concussion (n = 33; mean ± SD = 7.2 ± 3.1 days) and a group of uninjured athletes (n = 31) completed a Postconcussion Symptom Scale, underwent NPC testing, and single/dual-task gait assessments. INDEPENDENT VARIABLES: Near point of convergence was defined as the patient-reported diplopia distance when a fixation target moved toward the nose. Receded NPC was defined as a distance >5 cm from the tip of the nose. MAIN OUTCOME MEASURES: Spatiotemporal gait characteristics in single-task and dual-task conditions were evaluated with analysis of variance; correlations were calculated between NPC and gait measures. RESULTS: Eighteen of 33 (55%) patients with concussion presented with receded NPC. Those with receded NPC exhibited slower gait speed (single-task = 1.06 ± 0.14 m/s vs 1.19 ± 0.15 m/s; dual-task = 0.80 ± 0.13 m/s vs 0.94 ± 0.13 m/s; P = 0.003) and shorter stride lengths (single-task = 1.11 ± 0.10 m vs 1.24 ± 0.11 m; dual-task = 0.97 ± 0.11 m vs 1.09 ± 0.11 m; P = 0.001) than healthy controls. Near point of convergence was moderately correlated with dual-task average walking speed for the normal NPC group (ρ = -0.56; P = 0.05). Postconcussion Symptom Scale scores did not significantly differ between groups (27 ± 18 vs 28 ± 16). CONCLUSIONS: After concussion, adolescents with receded NPC exhibited significant gait-related deficits compared with healthy controls, whereas those with normal NPC did not. Vergence and gross motor system dysfunction may be associated after concussion. Gait and vergence measures may contribute useful information to postconcussion evaluations.


Assuntos
Traumatismos em Atletas/fisiopatologia , Concussão Encefálica/fisiopatologia , Marcha , Síndrome Pós-Concussão/fisiopatologia , Transtornos da Visão/diagnóstico , Adolescente , Traumatismos em Atletas/diagnóstico , Concussão Encefálica/diagnóstico , Estudos de Casos e Controles , Criança , Estudos Transversais , Feminino , Humanos , Masculino , Síndrome Pós-Concussão/diagnóstico
11.
Invest Ophthalmol Vis Sci ; 54(7): 4648-58, 2013 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-23761088

RESUMO

PURPOSE: To investigate photoreceptor and postreceptor retinal function in patients with congenital stationary night blindness (CSNB). METHODS: Forty-one patients with CSNB (ages 0.19-32 years) were studied. ERG responses to a series of full-field stimuli were obtained under scotopic and photopic conditions and were used to categorize the CSNB patients as complete (cCSNB) or incomplete (iCSNB). Rod and cone photoreceptor (R(ROD), S(ROD), R(CONE), S(CONE)) and rod-driven postreceptor (V(MAX), log σ) response parameters were calculated from the a- and b-waves. Cone-driven responses to 30 Hz flicker and ON and OFF responses to a long duration (150 ms) flash were also obtained. Dark-adapted thresholds were measured. Analysis of variance was used to compare data from patients with cCSNB, patients with iCSNB, and controls. RESULTS: We found significant reduction in saturated photoreceptor amplitude (R(ROD), R(CONE)) but normal photoreceptor sensitivity (S(ROD), S(CONE)) in both CSNB groups. Rod-driven postreceptor response amplitude (V(MAX)) and sensitivity (log σ) were significantly reduced in CSNB. Log σ was significantly worse in cCSNB than in iCSNB; this was the only scotopic parameter that differed between the two CSNB groups. Photopic b-wave amplitude increased monotonically with stimulus strength in CSNB patients rather than showing a normal photopic hill. The amplitude of the 30-Hz flicker response was reduced compared with controls, more so in iCSNB than in cCSNB. The mean dark-adapted threshold was significantly elevated in CSNB, more so in cCSNB than in iCSNB. CONCLUSIONS: These results are evidence of normal photoreceptor function (despite the low saturated photoresponse amplitude) and anomalous postreceptor retinal circuitry.


Assuntos
Adaptação à Escuridão/fisiologia , Cegueira Noturna/fisiopatologia , Células Fotorreceptoras Retinianas Cones/fisiologia , Células Fotorreceptoras Retinianas Bastonetes/fisiologia , Adolescente , Adulto , Análise de Variância , Criança , Pré-Escolar , Eletrorretinografia , Feminino , Humanos , Lactente , Masculino , Cegueira Noturna/congênito , Limiar Sensorial/fisiologia , Adulto Jovem
12.
Doc Ophthalmol ; 117(3): 197-203, 2008 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-18357480

RESUMO

PURPOSE: Under certain conditions, the full-field flicker electroretinogram (ERG) of the cone system can show period doubling, such that the shape of the ERG waveform alternates from cycle to cycle. The purpose of this study was to determine the relationship between stimulus temporal frequency and the amplitudes of the spectral components of the ERG that correspond to period doubling. METHOD: ERGs were recorded from 10 visually normal subjects in response to full-field sinusoidal flicker presented at frequencies ranging from 12.5 to 100 Hz. Period doubling was apparent over the stimulus frequency range from 25 to 100 Hz and was quantified in terms of the amplitudes of spectral components of the ERG waveform that corresponded to half the stimulus frequency (f/2) and three and five times that frequency (3f/2 and 5f/2). RESULTS: At stimulus frequencies between 30 and 40 Hz, the amplitude of f/2 was significantly lower than either 3f/2 or 5f/2, which themselves did not differ significantly. At stimulus frequencies between 40 and 60 Hz, all three response components were equivalent in amplitude. At stimulus frequencies above 60 Hz, however, the amplitudes of 3f/2 and 5f/2 were reduced significantly compared to f/2. CONCLUSION: There is a frequency-dependent relationship among the spectral components of the flicker ERG that correspond to period doubling. The amplitude of f/2 underestimates the magnitude of period doubling at stimulus frequencies between 30 and 40 Hz, whereas the amplitudes of 3f/2 and 5f/2 underestimate the degree of period doubling at stimulus frequencies above 60 Hz. The explanation for the frequency dependence of these spectral components remains to be resolved.


Assuntos
Eletrorretinografia/métodos , Luz , Células Fotorreceptoras Retinianas Cones/fisiologia , Adulto , Análise de Fourier , Humanos , Pessoa de Meia-Idade
13.
Vision Res ; 47(4): 555-63, 2007 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-17074380

RESUMO

At temporal frequencies between approximately 30 and 70 Hz, the flicker electroretinogram (ERG) of the cone system can exhibit an alternation in response amplitude from cycle to cycle that has been termed synchronous period doubling. This phenomenon has been attributed to a nonlinear feedback mechanism at an early retinal locus. The purpose of the present study was to define the effect of stimulus contrast on period doubling in order to better understand the nature of the underlying mechanism. ERGs were recorded from three visually normal subjects in response to sinusoidal flicker ranging from 20 to 100 Hz, using stimulus contrasts of 37.7, 56.5, 75.4, and 94.2%. Period doubling was quantified as: (1) the amplitude of an harmonic component of the ERG waveform that was 1.5 times the stimulus frequency, and (2) the difference between the mean trough-to-peak amplitudes on even and odd cycles of the ERG waveform. Amplitudes were converted to responsivity by dividing by stimulus contrast. By both measures, subjects showed discrete regions of period doubling that were displaced to lower temporal frequencies as stimulus contrast was increased. The temporal frequency shift of period doubling with altered stimulus contrast can be accounted for quantitatively by postulating a neural threshold for the nonlinear feedback signal that is presumed to generate synchronous period doubling.


Assuntos
Sensibilidades de Contraste/fisiologia , Células Fotorreceptoras Retinianas Cones/fisiologia , Adulto , Eletrorretinografia , Retroalimentação/fisiologia , Feminino , Humanos , Pessoa de Meia-Idade , Modelos Psicológicos , Estimulação Luminosa/métodos , Limiar Sensorial/fisiologia
14.
Vision Res ; 46(22): 3941-8, 2006 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16750238

RESUMO

The purpose of this study was to determine whether cone redepolarization accounts for the amplitude increase of the b-wave of the human electroretinogram (ERG) during light adaptation. The time course of the b-wave amplitude increase was compared to the time course of the change in the activation phase of cone phototransduction, as derived from a delayed Gaussian model applied to the leading edge of the ERG a-wave. ERG recordings were obtained from five visually normal subjects, alternately in the presence of the adapting field (adapt-on condition) and 300ms after its temporary extinction (adapt-off condition). The proportional increase in amplitude was less for R(mp3) (maximum amplitude of P3, the massed cone photoreceptor response) than for the b-wave for both adaptation conditions, and the time course of the amplitude increase for R(mp3) was faster than that for the b-wave in the adapt-off condition. The results demonstrate that time-dependent changes in the activation phase of cone phototransduction have only a minimal role in governing the increase in the amplitude of the human cone-derived ERG b-wave during light adaptation. In addition, the systematic increase in b-wave amplitude and the decrease in b-wave implicit time in the adapt-off condition indicates that the ERG response measured shortly after adapting field offset does not necessarily represent the waveform of the dark-adapted cone ERG.


Assuntos
Adaptação Ocular/fisiologia , Células Fotorreceptoras Retinianas Cones/fisiologia , Visão Ocular/fisiologia , Adulto , Adaptação à Escuridão , Eletrorretinografia/métodos , Feminino , Humanos , Pessoa de Meia-Idade , Estimulação Luminosa/métodos , Fatores de Tempo
15.
Vision Res ; 46(17): 2773-85, 2006 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16494917

RESUMO

This study examined the relationship between the activation phase of cone phototransduction and the flicker electroretinogram (ERG) in 15 patients with retinitis pigmentosa (RP) and 12 age-equivalent, visually normal control subjects. Values of Rmp3 (maximum amplitude of P3, the massed cone photoreceptor response) and S (sensitivity of cone phototransduction) were derived from a delayed Gaussian model applied to the leading edge of the ERG a-wave. Fundamental amplitude and phase of the flicker ERG were derived from responses to sinusoidal flicker presented at temporal frequencies ranging from 7.8 to 100 Hz. Patients with RP who had a reduced value of Rmp3 alone had an overall reduction in flicker ERG amplitude with a normal response phase across temporal frequency. Patients with RP who had a reduced value of S, whether or not Rmp3 was reduced, had the greatest amplitude reduction at temporal frequencies above 40 Hz and phase lags across a range of temporal frequencies. At high temporal frequencies, the amplitude reduction of the flicker ERG was predicted by the product of Rmp3 and S for all of the subjects except the three patients with RP who had the lowest fundamental amplitudes. The results indicate that there is a systematic relationship between the derived parameters of the activation phase of cone phototransduction and the characteristics of the flicker ERG in patients with RP, although the phase changes in the flicker ERG were generally greater than predicted by the derived parameters alone.


Assuntos
Células Fotorreceptoras Retinianas Cones/fisiologia , Retinite Pigmentosa/fisiopatologia , Visão Ocular , Adulto , Idoso , Eletrorretinografia , Feminino , Humanos , Iluminação , Masculino , Pessoa de Meia-Idade , Estimulação Luminosa/métodos
16.
J Opt Soc Am A Opt Image Sci Vis ; 22(10): 2262-8, 2005 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16277295

RESUMO

Thresholds were assessed for a speed discrimination task with a pair of luminance-defined drifting gratings. The design and results of a series of experiments dealing in general with speed discrimination are described. Results show that for a speed discrimination task using drifting gratings, simultaneous presentation of the pair of gratings (spatially separated) was preferred over sequential presentation (temporally separated) in order to minimize the effects of eye movements and tracking. An interstimulus interval of at least 1000 ms was necessary to prevent motion aftereffects on subsequently viewed stimuli. For the two reference speeds tested of 2 and 8 deg/s using identical spatial frequency or randomizing spatial frequency for the pair of gratings did not affect speed discrimination thresholds. Implementing a staircase method of estimating thresholds was preferred over the method of constant stimuli or the method of limits. The results of these experiments were used to define the methodology for an investigation of aging and motion perception. These results will be of interest and use to psychophysicists designing and implementing speed discrimination paradigms.


Assuntos
Adaptação Ocular/fisiologia , Discriminação Psicológica/fisiologia , Percepção de Movimento/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Estimulação Luminosa/métodos , Desempenho Psicomotor/fisiologia , Testes Visuais/métodos , Adulto , Humanos , Psicofísica , Projetos de Pesquisa , Limiar Sensorial/fisiologia , Campos Visuais/fisiologia
17.
J Opt Soc Am A Opt Image Sci Vis ; 22(10): 2269-80, 2005 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16277296

RESUMO

We studied the effects of aging on a speed discrimination task using a pair of first-order drifting luminance gratings. Two reference speeds of 2 and 8 deg/s were presented at stimulus durations of 500 ms and 1000 ms. The choice of stimulus parameters, etc., was determined in preliminary experiments and described in Part I. Thresholds were estimated using a two-alternative-forced-choice staircase methodology. Data were collected from 16 younger subjects (mean age 24 years) and 17 older subjects (mean age 71 years). Results showed that thresholds for speed discrimination were higher for the older age group. This was especially true at stimulus duration of 500 ms for both slower and faster speeds. This could be attributed to differences in temporal integration of speed with age. Visual acuity and contrast sensitivity were not statistically observed to mediate age differences in the speed discrimination thresholds. Gender differences were observed in the older age group, with older women having higher thresholds.


Assuntos
Adaptação Ocular/fisiologia , Envelhecimento/fisiologia , Discriminação Psicológica/fisiologia , Percepção de Movimento/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Estimulação Luminosa/métodos , Desempenho Psicomotor/fisiologia , Adulto , Idoso , Feminino , Humanos , Masculino , Psicofísica , Projetos de Pesquisa , Limiar Sensorial/fisiologia , Testes Visuais/métodos , Campos Visuais/fisiologia
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