Visual acuity testability and comparability in Australian preschool children: the Sydney Paediatric Eye Disease Study.
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ABSTRACT:
SUBMITTER: Leone JF
PROVIDER: S-EPMC3396162 | biostudies-other | 2012 Jul
REPOSITORIES: biostudies-other
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Project description:ObjectiveTo investigate risk factors associated with unilateral or bilateral decreased visual acuity (VA) in preschool children.DesignPopulation-based, cross-sectional prevalence study.ParticipantsPopulation-based samples of 6504 children ages 30 to 72 months from California and Maryland.MethodsParticipants were preschool African-American, Hispanic, and non-Hispanic white children from Los Angeles, California, and Baltimore, Maryland. Data were obtained by a parental interview and a detailed ocular examination. Logistic regression models were used to evaluate the independent associations between demographic, behavioral, and clinical risk factors with unilateral and bilateral decreased VA.Main outcome measuresOdds ratios (ORs) for various risk factors associated with interocular difference (IOD) in VA of ?2 lines with ?20/32 in the worse eye, or bilateral decreased VA <20/40 or <20/50 if <48 months of age.ResultsIn multivariate logistic regression analysis, 2-line IOD with a VA of ?20/32 was independently associated with Hispanic ethnicity (OR, 2.05), esotropia (OR, 8.98), spherical equivalent (SE) anisometropia (ORs ranging between 1.5 and 39.7 for SE anisometropia ranging between 0.50 to <1.00 diopters [D] and ?2.00 D), and aniso-astigmatism in J0 or J45 (ORs ranging between 1.4 and ?5.3 for J0 or J45 differences ranging between 0.25 to <0.50 D and ?1.00 D). Bilateral decreased VA was independently associated with lack of health insurance (OR, 2.9), lower primary caregiver education (OR, 1.7), astigmatism (OR, 2.3 and 17.6 for astigmatism 1.00 to <2.00 D and ?2.00 D), and SE hyperopia ?4.00 D (OR, 10.8).ConclusionsAnisometropia and esotropia are risk factors for IOD in VA. Astigmatism and high hyperopia are risk factors for bilateral decreased VA. Guidelines for the screening and management of decreased VA in preschool children should be considered in light of these risk associations.Financial disclosure(s)The authors have no proprietary or commercial interest in any of the materials discussed in this article.
| S-EPMC3208077 | biostudies-literature
Project description:High visual acuity is essential for many tasks, from recognizing distant friends to driving a car. While much is known about how the eye's optics and anatomy contribute to spatial resolution, possible influences from eye movements are rarely considered. Yet humans incessantly move their eyes, and it has long been suggested that oculomotor activity enhances fine pattern vision. Here we examine the role of eye movements in the most common assessment of visual acuity, the Snellen eye chart. By precisely localizing gaze and actively controlling retinal stimulation, we show that fixational behavior improves acuity by more than 0.15 logMAR, at least 2 lines of the Snellen chart. This improvement is achieved by adapting both microsaccades and ocular drifts to precisely position the image on the retina and adjust its motion. These findings show that humans finely tune their fixational eye movements so that they greatly contribute to normal visual acuity.
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Project description:Visual acuity is commonly assumed to be determined by the eye optics and spatial sampling in the retina. Unlike a camera, however, the eyes are never stationary during the acquisition of visual information; a jittery motion known as ocular drift incessantly displaces stimuli over many photoreceptors. Previous studies have shown that acuity is impaired in the absence of retinal image motion caused by eye drift. However, the relation between individual drift characteristics and acuity remains unknown. Here, we show that a) healthy emmetropes exhibit a large variability in their amount of drift and that b) these differences profoundly affect the structure of spatiotemporal signals to the retina. We further show that c) the spectral distribution of the resulting luminance modulations strongly correlates with individual visual acuity and that d) natural intertrial fluctuations in the amount of drift modulate acuity. As a consequence, in healthy emmetropes, acuity can be predicted from the motor behavior elicited by a simple fixation task, without directly measuring it. These results shed new light on how oculomotor behavior contributes to fine spatial vision.
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Project description:Dynamic visual acuity (DVA) is the ability to resolve fine spatial detail in dynamic objects during head fixation, or in static objects during head or body rotation. This ability is important for many activities such as ball sports, and a close relation has been shown between DVA and sports expertise. DVA tasks involve eye movements, yet, it is unclear which aspects of eye movements contribute to successful performance. Here we examined the relation between DVA and the kinematics of smooth pursuit and saccadic eye movements in a cohort of 23 varsity baseball players. In a computerized dynamic-object DVA test, observers reported the location of the gap in a small Landolt-C ring moving at various speeds while eye movements were recorded. Smooth pursuit kinematics-eye latency, acceleration, velocity gain, position error-and the direction and amplitude of saccadic eye movements were linked to perceptual performance. Results reveal that distinct eye movement patterns-minimizing eye position error, tracking smoothly, and inhibiting reverse saccades-were related to dynamic visual acuity. The close link between eye movement quality and DVA performance has important implications for the development of perceptual training programs to improve DVA.
| S-EPMC5302791 | biostudies-literature
Project description:To determine the prevalence and causes of decreased visual acuity (VA).Population-based cross-sectional study.Multi-ethnic sample of children 30 to 72 months of age identified in Los Angeles.All eligible children underwent a comprehensive ophthalmic evaluation including monocular VA testing, cover testing, cycloplegic autorefraction, fundus evaluation, and VA retesting with refractive correction. Decreased VA was defined as presenting or best-measured VA worse than 20/50 in children 30 to 47 months of age and worse than 20/40 for children 48 months of age and older. The prevalence and causes of decreased VA were determined, for both presenting and best-measured VA, in the better-seeing and the worse-seeing eyes.Prevalence and causes of decreased vision.Presenting VA was assessed in 1840 children and best-measured VA was assessed in 1886 children. Presenting VA was decreased in the worse eye of 4.2% of Asian children and of 3.6% of non-Hispanic white (NHW) children. Close to one-fourth of these cases had no identifiable cause, and 81% of these resolved on retesting. Decreased presenting VA in the worse eye with an identifiable ophthalmic cause was present in 3.4% of Asian children and in 2.6% of NHW children. Decreased presenting VA attributable to simple refractive error (myopia ? 0.5 diopters [D]; hyperopia ? 3.0 D; astigmatism ? 2.0 D or ? 1.5 D for children older than 36 months) was present in the worse eye of 2.3% of Asian children and of 1.4% of NHW children and in the better eye of 0.5% of Asian children and of 0.3% of NHW children. Decreased best-measured VA attributable to a cause was present in the worse eye of 1.2% of both Asian children and NHW children and in the better eye of 0.2% of Asian and of 0.3% of NHW children. Amblyopia related to refractive error was the most common cause, and was 10 times as common as ocular disease. Severe visual impairment was rare.Seventy percent of all decreased VA in Asian and NHW preschool children and more than 90% of decreased VA with an identifiable cause is related to refractive error--either uncorrected refractive error or amblyopia resulting from refractive error.The author(s) have no proprietary or commercial interest in any materials discussed in this article.
| S-EPMC4848010 | biostudies-literature
Project description:ObjectiveTo evaluate risk factors for astigmatism in a population-based sample of preschool children.DesignPopulation-based cross-sectional study.ParticipantsPopulation-based samples of 9970 children ages 6 to 72 months from Los Angeles County, California, and Baltimore, Maryland.MethodsA cross-sectional study of children participating in the Multiethnic Pediatric Eye Disease Study and the Baltimore Eye Disease Study was completed. Data were obtained by clinical examination or by in-person interview. Odds ratios and 95% confidence intervals (CI) were calculated to evaluate potential associations between clinical, behavioral, or demographic factors and astigmatism.Main outcome measuresOdds ratios (ORs) for various risk factors associated with astigmatism.ResultsParticipants with myopia (≤-1.0 diopters) were 4.6 times as likely to have astigmatism (95% CI, 3.56-5.96) than those without refractive error, whereas participants with hyperopia (≥+2.00 diopters) were 1.6 times as likely (95% CI, 1.39-1.94). Children 6 to <12 months of age were approximately 3 times as likely to have astigmatism than children 5 to 6 years of age (95% CI, 2.28-3.73). Both Hispanic (OR, 2.38) and African-American (OR, 1.47) children were as likely to have astigmatism than non-Hispanic white children. Furthermore, children whose mothers smoked during pregnancy were 1.46 times (95% CI, 1.14-1.87) as likely to have astigmatism than children whose mothers did not smoke.ConclusionsIn addition to infancy, Hispanic and African-American race/ethnicity and correctable/modifiable risk factors such as myopia, hyperopia, and maternal smoking during pregnancy are associated with a higher risk of having astigmatism. Although the prevalence of smoking during pregnancy is typically low, this association may suggest etiologic pathways for future investigation.Financial disclosure(s)The authors have no proprietary or commercial interest in any of the materials discussed in this article.
| S-EPMC3186875 | biostudies-literature
Project description:To determine the sex- and ethnicity-specific prevalence of color vision deficiency (CVD) in black, Asian, Hispanic, and non-Hispanic white preschool children.Population-based, cross-sectional study.The Multi-Ethnic Pediatric Eye Disease Study is a population-based evaluation of the prevalence of vision disorders in children in Southern California. A total of 5960 subjects 30 to 72 months of age were recruited for the study, of whom 4177 were able to complete color vision testing (1265 black, 812 Asian, 1280 Hispanic, and 820 non-Hispanic white).Color vision testing was performed using Color Vision Testing Made Easy color plates (Home Vision Care, Gulf Breeze, FL), and diagnostic confirmatory testing was performed using the Waggoner HRR Diagnostic Test color plates (Home Vision Care).Testability of color vision in preschool children between 30 and 72 months of age and prevalence of CVD stratified by age, sex, and ethnicity.Testability was 17% in children younger than 37 months of age, increasing to 57% in children 37 to 48 months of age, 89% in children 49 to 60 months of age, and 98% in children 61 to 72 months of age. The prevalence of CVD among boys was 1.4% for black, 3.1% for Asian, 2.6% for Hispanic, and 5.6% for non-Hispanic white children; the prevalence in girls was 0.0% to 0.5% for all ethnicities. The ethnic difference in CVD was statistically significant between black and non-Hispanic white children (P = 0.0003) and between Hispanic and non-Hispanic white children (P = 0.02). In boys, most CVD cases were either deutan (51%) or protan (34%); 32% were classified as mild, 15% as moderate, and 41% as severe.Testability for CVD in preschool children is high by 4 years of age. The prevalence of CVD in preschool boys varies by ethnicity, with the highest prevalence in non-Hispanic white and lowest in black children.
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Project description:SIGNIFICANCE:Identification of the association of specific signs of dry eye disease with specific visual function deficits may allow for more targeted approaches to treatment. PURPOSE:The purpose of this study was to explore the association of dry eye signs and symptoms with visual acuity (VA) and contrast sensitivity in the Dry Eye Assessment and Management study. METHODS:Baseline data from participants in the Dry Eye Assessment and Management study were used in this secondary cross-sectional analysis. Standardized procedures were used to obtain results on the Ocular Surface Disease Index (OSDI), high-contrast logMAR VA, contrast sensitivity, tear film debris, tear breakup time (TBUT), corneal fluorescein staining, meibomian gland evaluation, conjunctival lissamine green staining, and Schirmer test scores. Generalized linear models that included age, refractive error status, and cataract status were used to assess the association between VA and contrast sensitivity with OSDI score and each dry eye sign. The Hochberg procedure was used to account for multiple comparisons. RESULTS:Among 487 participants (974 eyes), worse VA was associated with worse mean score on the OSDI vision subscale (39.4 for VA 20/32 or worse vs. 32.4 for VA 20/16 or better; adjusted linear trend, P = .02); scores were not associated with contrast sensitivity. Severe meibomian gland plugging and abnormal secretions were associated with worse mean log contrast sensitivity (1.48 for severe vs. 1.54 for not plugged [P = .04] and 1.49 for obstructed vs. 1.57 for clear [P = .002], respectively). Longer TBUT was associated with better mean log contrast sensitivity (1.57 for TBUT >5 seconds and 1.51 for TBUT ≤2 seconds, P < .0001). CONCLUSIONS:Worse VA rather than worse contrast sensitivity drives vision-related symptoms in dry eye. Greater tear film instability was associated with worse contrast sensitivity.
| S-EPMC6544497 | biostudies-literature
Project description:Humans can distinguish visual stimuli that differ by features the size of only a few photoreceptors. This is possible despite the incessant image motion due to fixational eye movements, which can be many times larger than the features to be distinguished. To perform well, the brain must identify the retinal firing patterns induced by the stimulus while discounting similar patterns caused by spontaneous retinal activity. This is a challenge since the trajectory of the eye movements, and consequently, the stimulus position, are unknown. We derive a decision rule for using retinal spike trains to discriminate between two stimuli, given that their retinal image moves with an unknown random walk trajectory. This algorithm dynamically estimates the probability of the stimulus at different retinal locations, and uses this to modulate the influence of retinal spikes acquired later. Applied to a simple orientation-discrimination task, the algorithm performance is consistent with human acuity, whereas naive strategies that neglect eye movements perform much worse. We then show how a simple, biologically plausible neural network could implement this algorithm using a local, activity-dependent gain and lateral interactions approximately matched to the statistics of eye movements. Finally, we discuss evidence that such a network could be operating in the primary visual cortex.
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Project description:In clinical practice Cerebral Visual Impairment (CVI) is typically diagnosed by observation of abnormal visually guided behaviors which indicate higher visual function deficits (HVFDs) suggesting abnormal brain development or brain damage in a child with a suitable clinical history. HVFDs can occur even in the presence of good visual acuity and may remain undiagnosed because the good visual acuity does not prompt further investigation. This leads to a lack of understanding of the child's visual perceptual difficulties. In a prospective study, we determined the spectrum of HVFDs in a group of children with history suggestive of brain damage or disruption of brain development and an independent diagnosis of CVI in comparison with typically developing children with a structured 51 question inventory, the Higher Visual Function Question Inventory (HVFQI-51) adapted from the Cerebral Vision Impairment Inventory, CVI-I. Here, we show that the HVFQI-51 can detect a range of HVFDs in children with CVI with good visual acuity and clearly distinguishes these children from typically developing children. HVFDs in our study group could mostly be attributed to dorsal stream visual processing dysfunction though the spectrum varied between children. We report on the inclusion of the "not applicable" response option in analysis providing a picture of HVFDs more in tune with the overall disability of each child. We also propose a subset of 11 questions (Top-11) which discriminate between children with CVI vs. behaviors seen in typical children: this provides both a potential screening tool for initial assessment of HVFDs and a measure of CVI-related impairment, and needs further validation in a secondary independent sample.
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