Crash risk among older drivers studied.
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Accidents, Traffic↗
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Results for “Vision Tests”
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Asymmetric suppression outside the classical receptive field of the visual cortex.
Areas beyond the classical receptive field (CRF) can modulate responses of the majority of cells in the primary visual cortex of the cat (). Although general characteristics of this phenomenon have been reported previously, little is known about the detailed spatial organization of the surrounds. Previous work suggests that the surrounds may be uniform regions that encircle the CRF or may be limited to the "ends" of the CRF. We have examined the spatial organization of surrounds of single-cell receptive fields in the primary visual cortex of anesthetized, paralyzed cats. The CRF was stimulated with an optimal drifting grating, whereas the surround was probed with a second small grating patch placed at discrete locations around the CRF. For most cells that exhibit suppression, the surrounds are spatially asymmetric, such that the suppression originates from a localized region. We find a variety of suppressive zone locations, but there is a slight bias for suppression to occur at the end zones of the CRF. The spatial pattern of suppression is independent of the parameters of the suppressive stimulus used, although the effect is clearest with iso-oriented surround stimuli. A subset of cells exhibit axially symmetric or uniform surround fields. These results demonstrate that the surrounds are more specific than previously realized, and this specialization has implications for the processing of visual information in the primary visual cortex. One possibility is that these localized surrounds may provide a substrate for figure-ground segmentation of visual scenes.
Animals↗
Squint--what to do and when.
Squint is unfortunately a neglected subject in our country. It is considered only a cosmetic problem without realising that any manifest squint is a one eyed blindness which results in lack of binocular vision. Consequently there is no stereopsis. The management should be undertaken at the earliest possible age when development of uni-ocular as well as binocular vision is taking place. Once the visual system is mature, only cosmetic appearance can be improved, but not the vision.
Age Factors↗
[Morphoscopic perception at variable contrast and luminance levels in 97 subjects].
BACKGROUND: Morphoscopic perception at variable contrast and luminance levels has been assessed in various diseases and in occupational medicine. To our knowledge, this function has not been studied in young adults of similar age. We performed a prospective study to assess morphoscopic perception at variable contrast and luminance levels in a group of young servicemen. METHODS: A total of 97 subjects (194 eyes) with a mean age of 22.4 (standard deviation 1.16) years were assessed with the Gradual monitor. After visual acuity was measured, morphoscopic perception was assessed at a mean light level of 85 cd/m2, at low, medium and high spatial frequencies, with myopic correction. All subjects whose visual acuity was not correctable to 10/10 in both eyes or whose score was statistically too different from the mean underwent a complete ophthalmologic examination. RESULTS: Overall, 87 subjects had a visual acuity correctable to 10/10 or better in both eyes. For 34 of the 87, at least one of the six scores was more than 1 standard deviation below the mean; however, for 16 subjects the result was within normal limits after minor adjustment of the correction, often of a small degree of astigmatism. Of the 18 remaining subjects 7 had microstrabismus, 8 had anatomic lesions and 3 had lesions of unknown origin. Of the 13 subjects with a visual acuity of less than 10/10, 5 had relative amblyopia, 2 had major ametropia, 2 had unilateral and 2 bilateral ophthalmologic lesions, and 2 had reduced acuity of unknown cause. INTERPRETATION: In this young population the most frequent cause of reduced contrast sensitivity (40%) was associated with minor uncorrected or badly corrected refractive problems. The next most frequent cause was problems with binocular vision, with or without amblyopia (11%). In these subjects contrast sensitivity was reduced in the nondominant eye and, in five cases, in the dominant eye also.
Adult↗
Recommendations for the school health physical examination in Lebanon.
School health developed gradually over the years; starting with efforts to keep contagion out of schools to global programs of comprehensive services. One of its components, school medicine, covers screening examinations, record maintenance, emergency care, immunization monitoring and health counseling. This paper proposes the essential health activities to be performed during a screening school examination in Lebanon. The recommendations are based on a combination of international literature review of evidence and the existence of Lebanese epidemiological reports identifying specific problems. Vaccination record review, tuberculin testing, vision, hearing, dental and skin disorders screening procedures are proposed as essential activities of the school physical examination.
Child↗
[Low visual acuity, disorders of the visual field: how to adapt the imaging of optical pathways to clinical practice?].
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Diagnostic Imaging↗
The use of binocular visual acuity in the assessment of intermittent exotropia.
BACKGROUND: It has been suggested that a decrease in distance stereoacuity in patients with intermittent exotropia is a good indicator of diminishing control. However, there has been no adequate explanation for this reported reduction in distance stereoacuity in these patients. We postulate that the decrease in stereoacuity is related to blurred visual acuity created by an increasing demand on accommodation, which these patients use in an attempt to control the exodeviation. This can best be assessed by measuring binocular visual acuity (BVA). Analysis of BVA could provide a useful clinical tool to evaluate control measures used by patients with intermittent exotropia. METHODS: A prospective study of patients with intermittent exotropia, ranging in age from 6 to 60 years, was performed. Only those patients with the presence of either basic or divergence excess (simulated or true) type exodeviation were included in the study. The data analysis included the age of these patients, age at onset of the deviation, monocular and binocular visual acuity, oculomotor and fusional status, and near and distance stereoacuity. RESULTS: Data from 36 patients show that the measurements of BVA correlated well with a corresponding loss of distance stereoacuity but not with the size of the deviation. CONCLUSION: The decrease of stereoacuity reported in patients with exotropia can be explained by increased accommodation and decreased distance BVA. This measurement can be a simple method of quantifying the fusional control of patients with intermittent exotropia.
Accommodation, Ocular↗
Monocular versus binocular visual acuity as measures of vision impairment and predictors of visual disability.
PURPOSE: To examine the relationship between monocular and binocular visual acuities as predictors of visual disability in a population-based sample of individuals 65 years of age and older. METHODS: Two thousand five hundred twenty community-dwelling residents of Salisbury, Maryland, between the ages of 65 and 84 years of age were recruited for the study. Corrected visual acuity was measured monocularly and binocularly using ETDRS charts. Reading speed, face discrimination, and self-reported difficulty with visual tasks were also determined. RESULTS: Binocular acuity is predicted with reasonable accuracy by acuity in the better eye alone, but not by the widely used American Medical Association (AMA) weighted-average algorithm. The AMA algorithm significantly underestimates binocular acuity when the interocular acuity difference exceeds one line. Monocular acuity and binocular acuity were significantly better predictors of reading speed than the AMA weighted score or a recently proposed Functional Vision Score (FVS). Monocular acuity in the better eye, binocular acuity, and the AMA and FVS algorithms were equally good predictors of self-reported vision disability. None of the acuity measures were good predictors of face recognition ability. CONCLUSIONS: The binocular acuities of older individuals can be inferred from measures of monocular acuity. There is little evidence for binocular inhibition when the monocular acuities in the two eyes are unequal, as opposed to the widely used AMA algorithm for computing binocular visual impairment. For tasks that are strongly associated with visual acuity, such as reading, this association can be captured from measures of monocular acuity and does not require separate assessment of binocular acuity.
Aged↗
Spatial localization in esotropia: does extraretinal eye position information change?
PURPOSE: To investigate the accuracy of spatial localization in children with a specific type of convergent strabismus, fully accommodative esotropia. METHODS: Two groups of children, with right and left fully accommodative esotropia, respectively, pointed at targets located centrally and eccentrically on a computer touchscreen without being able to see their hands. The size and the direction of the horizontal pointing responses were recorded under two conditions: when their eyes were aligned (wearing spectacles) and when they were squinting (not wearing spectacles). A group of children without strabismus but with hypermetropia were assessed as controls. RESULTS: For both fully accommodative groups, the pointing responses to the central target shifted in the direction of the nonsquinting eye when deviations were manifest. No difference was found for the eccentric targets. No difference was found for the hypermetropia group with any target. CONCLUSIONS: These results are consistent with an alteration in the extraretinal eye position information (efference copy, extraocular muscle proprioception, or both) that is used in spatial localization.
Accommodation, Ocular↗
Ocular phenotype of bothnia dystrophy, an autosomal recessive retinitis pigmentosa associated with an R234W mutation in the RLBP1 gene.
OBJECTIVE: To describe the phenotype of Bothnia dystrophy, an autosomal recessive retinal dystrophy with an R234W mutation in the RLBP1 gene encoding cellular retinaldehyde-binding protein. DESIGN: Medical records were reviewed retrospectively. Ophthalmologic examination, including kinetic perimetry and, in selected cases, adaptometry, color vision tests, fluorescein angiography, and electrophysiologic studies, was performed. The study included 24 individuals, all homozygous for an R234W mutation in the RLBP1 gene. RESULTS: Patients typically show night blindness from early childhood. In young adults, retinitis punctata albescens was observed, followed by macular degeneration and a decrease in visual acuity that led to legal blindness in early adulthood. Dark adaptometry and electrophysiologic testing showed an initial loss of rod function followed by a progressive reduction of the cone responses in older ages. CONCLUSIONS: Bothnia dystrophy is a unique retinal dystrophy belonging to the rod-cone dystrophies and has a high prevalence in northern Sweden. Fifty-seven cases of Bothnia dystrophy have been diagnosed, indicating a prevalence as high as 1 per 4500 population in the geographic area studied. A defect ability of mutated cellular retinaldehyde-binding protein to bind retinoid probably explains the defect rod function followed by central and peripheral degeneration. CLINICAL RELEVANCE: Retinal dystrophies associated with other mutations of the RLBP1 gene, including retinitis pigmentosa of Bothnia type, might account for a considerable number of cases of autosomal recessive retinitis pigmentosa in other geographic areas as well.
Adolescent↗
Psychometric properties of the 25-item NEI-VFQ in a Hispanic population: Proyecto VER.
PURPOSE: To assess the psychometric properties of the NEI-VFQ-25 in a population-based study of older Hispanic persons living in the United States, explore other demographic factors that affect participant response, and observe the comparability of the Spanish and English versions of the instrument. METHODS: A sample of randomly selected block groups in Tucson and Nogales, Arizona, were selected for study. Participants were interviewed at home; a majority of the interviews were conducted in Spanish. The home interview included questions from the NEI-VFQ-25 and HHANES: Presenting acuity was done using ETDRS methodology, followed by a standardized eye examination by an ophthalmologist. The authors analyzed the internal consistency of the NEI-VFQ-25 responses using Cronbach's alpha coefficient and the construct validity by assessing the relationship between presenting acuity and scale scores, adjusting for age and gender. A second model was also explored to determine whether other demographic variables affected scale scores; differences in reporting between the Spanish and English versions was observed in this model, used in a subset of the population that minimized interviewer effect. RESULTS: Of the 4774 participants in the study, 99.7% had completed questionnaires, not completed by proxy. The highest nonresponse rate occurred in the Driving scale, with 25% of participants not driving for reasons other than problems with vision. Internal consistency was high, with Cronbach alpha ranging between 0.65 and 0.86 for scales with multiple items. Adjusting for age and gender, those with presenting acuity worse than 20/40 scored significantly lower than those with presenting acuity 20/40 or better, for all scales. The demographic variables with the most consistent association across the NEI-VFQ-25 scales were presenting acuity, income, and gender. No significant differences in reporting were found between the Spanish and English versions of the questionnaire in the subset of the population. CONCLUSIONS: In this study of Hispanic people age 40 years or older, the NEI-VFQ-25 was sensitive to presenting acuity and other demographic variables, such as age, gender, and income. The findings from this psychometric analysis provide evidence of the reliability and validity of some of the scales in the 25-item NEI-VFQ when used among people with a range of visual acuity level, providing other explanatory variables are also considered.
Activities of Daily Living↗
Vergence adaptation in children and its clinical significance.
BACKGROUND AND PURPOSE: Vergence adaptation has not been well investigated in children even though it may contribute to binocular dysfunction and near work induced asthenopia. METHODS: We compared vergence adaptation in 18 children and 18 young adult subjects by assessing tonic vergence (TV) before and immediately after a period of sustained near fixation, by measuring heterophoria with a synoptophore through 0.5 mm binocular pinholes. Adaptation was induced by a reading task at 15 cm for a continuous 5 minute period. RESULTS: Mean pre-task TV values of 0.70 MA (Meter Angles) and 0.20 MA were observed for the children and young adults, respectively (p = 0.08). The initial mean vergence adaptation for children and adults was +0.45 MA and +0.11 MA, respectively (p = 0.001). CONCLUSION: The greater vergence adaptation observed in children may impact upon the clinical assessment of their binocular vision, especially heterophoria measurement which may require longer periods of dissociation than previously recommended, and might also ultimately be partly responsible for the predominant development of esodeviations during childhood
Adaptation, Ocular↗
[Functional state of the visual analyzer in naval specialists].
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Humans↗
Variable tinted spectacle lenses: a comparison of aesthetics and visual preference.
PURPOSE: To determine the correlation between the aesthetics of lens tints preferred for cosmesis and lens tints preferred for viewing. METHODS: Thirty-five subjects (mean age: 25; 49% male, 51% female) with no significant ocular pathology participated in the study. Median visual acuity was 20/20. Color vision testing was performed on each subject using Ishihara plates, and those with abnormal scores were excluded from the study. Subjects were shown nine pre-selected tinted lenses (50% transmittance) of variable wavelengths. These lenses were mounted on two separate color backgrounds, one white and the other approximating their skin tone. Subjects were asked to choose from each background which tinted lens they would most prefer to wear and which lens they would least prefer to wear. The subjects were then shown a series of eight pictures (four nature photographs and four paintings) with different dominant wavelengths. Subjects were asked to grade the aesthetic effect of a clear lens and each of the nine tinted lenses on the appearance of the pictures. Chromaticity coordinates were calculated for each lens and picture. RESULTS: The blue lens was the most frequently chosen preferred lens to wear, followed by green, purple, and gray. The least preferred lenses were yellow, brown, and pink. For viewing the nature photographs, the clear lens was preferred over any of the tinted lenses. For viewing the paintings, the purple lens was most preferred. The yellow lens was least preferred for both photographs and paintings. CONCLUSIONS: Younger individuals with no significant ocular pathology preferred viewing both nature photographs and paintings through tinted lenses that did not, or only slightly, altered the chromaticity of the image. Whereas a clear lens was favored over the tinted lenses for viewing the photographs, some tinted lenses (purple and pink) were preferred for viewing paintings. There was no correlation between the most favored lens tint chosen based purely on cosmesis and the most favored lens tint based on viewing preference. However, the least preferred lens tint for cosmesis and viewing was yellow.
Adult↗
Quantitative examination of neurological function: reliability and learning effects.
During the last five years, a battery of tests measuring neurological function called the Quantitative Examination of Neurological Function (QENF) has been greatly expanded. To evaluate more effectively the efficacy of clinical trials, the results of a study on reliability of test measures and on long- and short-term effects of learning are reported. Of the 113 test measures that were evaluated using 18 young adult normal subjects, only the fatigue and error measures, the vibration sense and two simulated activities of daily living tests were found unreliable. With respect to learning, the largest improvements in performance were found for arm-shoulder pursuit tracking, followed by many of the tests of coordination, particularly those requiring manual and/or finger dexterity. Only slight changes were found for tests of vision, strength, and speed of hand and foot. There were no important differences between short- and long-term learning. Considering this and other studies, patients are not likely to improve their performance appreciably by learning in a clinical trial.
Activities of Daily Living↗
Changing clinician practice. The RACGP/RACO National GP Eye Skills Workshop.
AIM: To evaluate the impact of the Royal Australian College of General Practitioners (RACGP)/Royal Australian College of Ophthalmologists National General Practitioner Eye Skills Workshop on Queensland participants reported medium and long term ocular practice pattern. METHOD: Two questionnaires were administered to all Queensland workshop participants (n = 121), six months and > 12 months following the workshop, to assess self reported ocular practice pattern. RESULTS: The response rate was identical for both the first and second questionnaire with 78 (64%) GPs returning completed forms on each occasion. Results indicate a highly significant increase in the proportion of GPs having access to dilating drops in the practice, using a systematic approach to eye assessment, and using the ocular kinetic perimetry (OKP) chart (p < 0.001), performing paediatric vision testing (p = 0.002) and incising chalazion (p = 0.01) following the workshop. General practitioners also reported a significant increase in the use of dilatation and fundoscopy in all clinical areas surveyed (p < 0.001). The change in dilatation and fundoscopy practice found at six months was sustained at > 12 months. CONCLUSION: Our study has demonstrated the National GP Eye Skills Workshop to be associated with significant and sustained practice change in key areas of ocular assessment in general practice. A key ingredient in the workshop's success was the focus on experiential learning, intra-session practice rehearsal and use of local opinion leaders.
Clinical Competence↗
[The results of surgical treatment of convergent strabismus (author's transl)].
From the results of 628 operations on strabismus convergens, the individual corrections were related to the achieved reduction of the angle of deviation. The evaluation showed that strabismus operations may be well dosed not only with a view to a general improvement of the squint angle but also as a specific influence on the squint angle as to distant vision and near vision.
Anesthesia, General↗