PubMed Health⌕ Search

Biomedical subjects

C Owsley

Publications and source records attributed to C Owsley.

At least 19 recordsLinked to original sources
PubMed1998

Visual processing impairment and risk of motor vehicle crash among older adults.

CONTEXT: Motor vehicle crash risk in older drivers has been associated with visual acuity loss, but only weakly so, suggesting other factors contribute. The useful field of view is a measure that reflects decline in visual sensory function, slowed visual processing speed, and impaired visual attention skills. OBJECTIVE: To identify whether measures of visual processing ability, including the useful field of view test, are associated with crash involvement by older drivers. DESIGN: Prospective cohort study with 3 years of follow-up, 1990-1993. SETTING: Ophthalmology clinic assessment of community-based sample. PATIENTS: A total of 294 drivers aged 55 to 87 years at enrollment. MAIN OUTCOME MEASURE: Motor vehicle crash occurrence. RESULTS: Older drivers with a 40% or greater impairment in the useful field of view were 2.2 times (95% confidence interval, 1.2-4.1) more likely to incur a crash during 3 years of follow-up, after adjusting for age, sex, race, chronic medical conditions, mental status, and days driven per week. This association was primarily mediated by difficulty in dividing attention under brief target durations. CONCLUSION: Reduction in the useful field of view increases crash risk in older drivers. Given the relatively high prevalence of visual processing impairment among the elderly, visual dysfunction and eye disease deserve further examination as causes of motor vehicle crashes and injury.

Accidents, Traffic↗
PubMed1998

Identifying the content area for the 51-item National Eye Institute Visual Function Questionnaire: results from focus groups with visually impaired persons.

OBJECTIVE: To identify the content area for a questionnaire designed to measure vision-targeted health-related quality of life and to determine whether problems with vision-related functioning are qualitatively similar across different common eye diseases. DESIGN: Twenty-six condition-specific focus groups were conducted with 246 patients from 5 geographic regions to identify the content area for a questionnaire for use among persons with diabetic retinopathy, glaucoma, macular degeneration, cytomegalovirus retinitis, and cataract. A standard protocol was used to structure each focus group discussion. Sessions were audiotaped, transcribed, and coded in preparation for a content analysis. SETTINGS: Five university-based ophthalmology practices and 1 nonprofit eye care foundation. PARTICIPANTS: Eligible participants had to have 1 of the following eye conditions: age-related cataracts, age-related macular degeneration, diabetic retinopathy, primary open angle glaucoma, cytomegalovirus retinitis, or low vision from any cause. All eligible persons were older than 21 years, spoke English, and had sufficient cognitive function to provide informed consent. RESULTS: Among the 246 participants, 2623 problems with vision-related functioning were mentioned. The mean number of problems per person ranged from 13.5 for those with diabetic retinopathy to 7.9 for persons with glaucoma. For the sample overall, reading problems were mentioned most frequently, followed by driving, general problems with seeing clearly, and mental health complaints caused by vision. Although the proportion of persons who reported each problem varied by condition, at least some persons with each eye disease reported each problem. The 3 most common descriptors associated with each problem were difficulty or ease of performance (13%), psychological distress associated with performance of the activity (11%), and complete inability to participate in a visual activity (11%). CONCLUSION: An item-generation strategy for a new questionnaire using a standardized focus group method identified content areas and aspects of visual disability that are not included in currently available vision-specific instruments that assess the impact of common eye diseases on visual functioning in every-day life. Although participants mentioned problems that were unique to their disease, across conditions the problems mentioned were similar. These findings provide empirical evidence of content validity for a vision-targeted, health-related quality-of-life survey designed for use across conditions.

Adult↗
PubMed1998

A preliminary assessment of the medical and functional factors associated with vehicle crashes by older adults.

OBJECTIVES: To examine associations between medical and functional variables and at-fault car crashes in a cohort of older drivers. DESIGN: A case-control study. SETTING: A tertiary care medical center. PARTICIPANTS: Older drivers (ages 55-90 years) residing in Jefferson County, Alabama (n = 174). Cases were drivers who had at least one at-fault crash in the previous 6 years; controls were crash-free during the same period. MEASUREMENTS: Self-reported medical conditions, reported and observed functional measures, and urinary drug screens. The occurrence of one or more at-fault car crashes in the 6 years preceding the 1991 assessment date represented the outcome measure. RESULTS: Ninety-nine older drivers experienced between one and seven at-fault vehicle crashes during the period 1985 through 1991, whereas 75 drivers did not. Logistic regression models indicated that the following variables were independently associated with crash involvement: A 40% or greater reduction in the useful field of view (OR = 6.1; 95% CI, 2.9 to 12.7; P < 0.001), black race (OR = 6.6; 95% CI, 1.7 to 26.2; P = .007), a history of falling in the previous 2 years (OR = 2.6; CI, 1.1 to 6.1; P = .025), and not taking a beta-blocking drug (OR = 4.3; CI, 1.2 to 15.0; P = .023). CONCLUSIONS: Functional assessments, such as a comprehensive test of visual processing, a falls history, and a review of current medications may be of greater relevance than specific medical conditions in the identification of older at-risk drivers. If prospective studies determine that falling and crashing share risk factors, a unified approach to the prevention of these mobility disorders could result. The finding of an independent association of black race with at-fault crashing is in need of further clarification because of the low representation of black drivers in this sample.

Accidents, Traffic↗
PubMed1997

Driving after stroke: driving exposure, advice, and evaluations.

OBJECTIVE: Little is known about the extent to which stroke survivors return to driving and the advice and/or evaluations they receive about driving. This study sought to estimate the prevalence of driving after stroke and to determine whether stroke survivors receive advice and evaluation about driving. DESIGN: A convenience sample of stroke survivors was surveyed regarding driving status following stroke, driving exposure, advice received about driving, and evaluation of driving performance. PARTICIPANTS: Two hundred ninety stroke survivors who were between 3 months to 6 years poststroke. RESULTS: Thirty percent of stroke survivors who drove before the stroke resumed driving after the stroke. Stroke survivors are often poorly informed by health care professionals about driving, with 48% reporting that they did not receive advice about driving and 87% reporting that they did not receive any type of driving evaluation. Almost one third of poststroke drivers had high exposure, driving 6 to 7 days per week and/or 100 to 200 miles per week. CONCLUSIONS: These findings suggest that many stroke survivors are making decisions about their driving capabilities without professional advice and/or evaluation. The results also suggest that rehabilitation professionals need to devote more attention and resources to driving issues when working with stroke survivors and their families.

Adult↗
PubMed1995

Relationship between visual sensitivity and target localization in older adults.

Older adults commonly report problems in visual search tasks and experience a higher incidence of mobility problems (e.g. falls and vehicle crashes), which involve visual skills. We examined whether target localization problems in the elderly can be adequately explained by impairments in peripheral visual sensitivity, or whether deficits in higher order visual processing are also contributory. Fifty-nine older adults (59-88 yr) who exhibited varying degrees of visual field loss (none to severe) were asked to localize briefly-presented, high-contrast targets (3 x 5 deg) in the central 60 deg (diameter) of the visual field, while simultaneously performing a visual discrimination task at fixation. Visual sensitivity accounted for only 36% of the variance in localization performance across subjects, and this relationship grew weaker (13%) when the target was embedded in distracting stimuli, suggesting that impaired attentional skills also underlie older adults' localization problems. Not surprisingly, older adults with severe visual field loss were also poor at localizing targets. However, about half of those older patients with normal or near-normal visual fields also had severe localization problems. These results indicate that despite having good visual field sensitivity, many older adults have serious difficulty locating objects of interest in the environment. This study illustrates that clinical tests for identifying visual performance problems in the elderly must embody stimulus and task features which better reflect the visual demands of everyday life.

Aged↗
PubMed1994

Vision and driving in the elderly.

BACKGROUND: This is an overview of a program of research to identify visual and cognitive factors which place older drivers at risk for vehicle crashes. METHODS: A sample of 294 older drivers participated in a protocol which assessed eye health, visual sensory function (i.e., acuity, contrast sensitivity, peripheral field sensitivity), the size of the useful field of view (UFOV), and cognitive status. The sample was age- and crash-stratified to ensure inclusion of older adults covering a wide range of ages (55 to 90 years) and crash frequencies during the previous 5 years (0 to 4 crashes). The major dependent variable was the number of at-fault crashes incurred during the 5-year period before our protocol test date (retrospective study) and during the 3-year period after our test date (prospective study). RESULTS: Older drivers with visual sensory impairment, cognitive impairment, and/or a constriction in the size of the useful field of view were at greater risk for crashes than were those without these problems. The UFOV test had better sensitivity and specificity than visual sensory or mental status tests in identifying those older drivers at risk for crashes. CONCLUSIONS: The UFOV test's superior predictability is most likely due to its reliance on both visual sensory abilities and higher order attentional skills. This study suggests that interventions which reduce either visual sensory or attentional impairment may also reduce accident risk in older drivers, an issue we are currently investigating.

Accidents, Traffic↗
PubMed1993

Aging and neural spatial contrast sensitivity: photopic vision.

This study investigated the extent to which older adults' loss in spatial contrast sensitivity at a photopic level is attributable to neural changes in the aged visual system. Laser interferometry was used to generate interference fringes which bypass the optics of the eye in presenting a grating target on the retina. Older adults in good eye health exhibited on average a small but statistically significant loss (0.1-0.2 log unit) in contrast sensitivity across the spatial frequency range tested, although there was considerable overlap between young and old adults. This loss in contrast sensitivity for interference fringes accounted for less than half of the photopic contrast sensitivity loss at higher frequencies reported for older adults in studies using conventional direct-viewing techniques in which the optics of the aged eye are not bypassed. We conclude that neural changes in the aged visual system have a rather minor contribution to older adults' loss in spatial contrast sensitivity at a photopic level.

Adolescent↗
PubMed1993

Modeling the contrast-sensitivity functions of older adults.

To determine whether a parabolic template is a good description of the contrast-sensitivity functions (CSF's) exhibited by older adults, the curve-fitting method of Pelli et al. [J. Opt. Soc. Am. A 3(13), P56 (1986)] was applied to contrast-sensitivity data from 100 older subjects (ages 53-85 years). Although the method resulted in reasonable fits for most subjects, closer inspection revealed that this technique may be problematic. A significant number of observers had functions that were nonparabolic, and for many subjects the error tended to be concentrated at the peak of the CSF. In addition, in contrast to the study of Pelli et al., the peak contrast sensitivities of the subjects were only weakly related to Pelli-Robson contrast sensitivity and letter acuity. The data were also fitted with an asymmetric function of variable shape. Whereas this function provided a better fit to the nonparabolic CSF's, it resulted in inferior fits to most of the remaining data. These results demonstrate that the spatial CSF's of older adults cannot be described by a single parametric curve such as a parabola or a function of an exponential and that Pelli-Robson contrast sensitivity and letter acuity are not adequate predictors of their peak contrast sensitivities.

Adolescent↗
PubMed1993

Visual attention problems as a predictor of vehicle crashes in older drivers.

PURPOSE: To identify visual factors that are significantly associated with increased vehicle crashes in older drivers. METHODS: Several aspects of vision and visual information processing were assessed in 294 drivers aged 55 to 90 years. The sample was stratified with respect to age and crash frequency during the 5-year period before the test date. Variables assessed included eye health status, visual sensory function, the size of the useful field of view, and cognitive status. Crash data were obtained from state records. RESULTS: The size of the useful field of view, a test of visual attention, had high sensitivity (89%) and specificity (81%) in predicting which older drivers had a history of crash problems. This level of predictability is unprecedented in research on crash risk in older drivers. Older adults with substantial shrinkage in the useful field of view were six times more likely to have incurred one or more crashes in the previous 5-year period. Eye health status, visual sensory function, cognitive status, and chronological age were significantly correlated with crashes, but were relatively poor at discriminating between crash-involved versus crash-free drivers. CONCLUSIONS: This study suggests that policies that restrict driving privileges based solely on age or on common stereotypes of age-related declines in vision and cognition are scientifically unfounded. With the identification of a visual attention measure highly predictive of crash problems in the elderly, this study points to a way in which the suitability of licensure in the older adult population could be based on objective, performance-based criteria.

Accidents, Traffic↗
PubMed1993

The useful field of view test: a new technique for evaluating age-related declines in visual function.

Many older adults eventually experience difficulty in everyday visual activities, prompting them to consult with an eye care specialist. In some cases, a thorough examination may reveal no clinical basis for these difficulties. New techniques for evaluating age-related declines in visual function have substantiated the existence of deficits in visual attention that are not adequately captured by standard clinical measures, and which are predictive of real world problems in driving and mobility. These new techniques may serve an important function in guiding the diagnosis, and treatment of those older adults experiencing functional visual problems.

Activities of Daily Living↗
PubMed1993

Assessing visual function in the older driver.

It is likely that some older adults will have to be restricted from driving because of serious and irreversible deterioration in skills crucial to driving, due to vision impairment, visual attention deficits, and decreased cognitive status; however many older adults with driving difficulties can improve their driving skills or reduce their crash risk through education or training programs. Research to evaluate interventions such as those previously mentioned has high priority, given society's need to maintain the mobility and personal independence of older adults without sacrificing safety concerns.

Accidents, Traffic↗
PubMed1991

Visual/cognitive correlates of vehicle accidents in older drivers.

Older drivers have more accidents per miles driven than any other age group and tend to have significant impairments in their visual function, which could interfere with driving. Previous research has largely failed to document a link between vision and driving in the elderly. We have taken a comprehensive approach by examining how accident frequency in older drivers relates to the visual/cognitive system at a number of levels: ophthalmological disease, visual function, visual attention, and cognitive function. The best predictor of accident frequency as recorded by the state was a model incorporating measures of early visual attention and mental status, which together accounted for 20% of the variance, a much stronger model than in earlier studies. Those older drivers with a visual attentional disorder or with poor scores on a mental status test had 3-4 times more accidents (of any type) and 15 times more intersection accidents than those without these problems.

Accidents, Traffic↗
PubMed1991

Identifying correlates of accident involvement for the older driver.

Most older adults rely on the automobile to maintain their mobility and independence, in spite of the fact that age-related behavioral and biomedical changes may make driving more difficult. Indeed, accident and fatality rates begin to rise after age 55. One research goal, therefore, is to identify functional measures that differentiate older adults who drive safely from those who do not. This paper discusses conceptual and methodological issues involved in addressing this question, considers why earlier research has been largely unsuccessful, presents a working model for approaching the problem, and argues the need for large-sample, prospective research in this area.

Accidents, Traffic↗
PubMed1988

Aging, senile miosis and spatial contrast sensitivity at low luminance.

The purpose of this study was to determine how aging affects spatial contrast sensitivity at low light levels and to examine whether senile miosis, which reduces retinal illuminance in the aged eye, underlies any observed sensitivity loss. Contrast thresholds for targets having a range of spatial frequencies were measured in young (n = 13, M age = 24) and older (n = 11, M age = 73) adults who were free from identifiable ocular pathology. Measurements were carried out at three luminance levels spanning a three log unit range. Results indicated that older adults' loss in contrast sensitivity not only increased with increasing spatial frequency, but also became more pronounced with decreases in luminance level. Additional threshold measurements where pupil diameter was varied indicated that senile miosis was not responsible for older adults' loss in spatial vision at any level tested. Rather, older adults' miotic pupil tended to have a positive effect on their spatial vision in that it slightly improved their contrast sensitivity.

Adult↗
PubMed1988

Aging and luminance-adaptation effects on spatial contrast sensitivity.

Contrast sensitivity as a function of target luminance for four spatial frequencies (0.5, 2, 4, and 8 cycles/deg) was measured in younger (n = 12; age range, 19-35 years) and older (n = 11; age range, 68-79 years) adults in order to examine the feasibility of optical and neural explanations for the impairment of contrast sensitivity in older adults. All subjects were free from identifiable ocular disease and had good acuity. Sensitivity for each spatial frequency was measured at eight luminance levels spanning 3.5 log units in the photopic-mesopic range. When gratings were flickered at 0.5 Hz, functions for older adults were displaced downward on the sensitivity axis across all luminance levels, and the slopes of these functions were steeper than those for younger adults, suggesting that optical mechanisms alone cannot account for the vision loss in older adults. Further measurements, in which spatial targets were flickered at 7.5 Hz, indicated that this faster temporal modulation affected sensitivity as a function of luminance differentially in younger and older adults. These data imply that the neural mechanisms subserving human spatial vision undergo significant changes during adulthood.

Adaptation, Physiological↗
PubMed1988

'Vision through my aging eyes' revisited.

A variety of age-related changes occur in the visual system of older adults who are free from identifiable eye disease. Normal aging of the eye can affect visual functioning in older adults, and a variety of psychophysical tests have documented some of these effects. Dr. Meredith Morgan, a distinguished optometric educator, describes many of these changes in his editorial "Vision Through My Aging Eyes." In this article, an overview of several common anatomical, physiological and psychophysical changes which occur in the eye with normal aging is provided, and specific observations made by Morgan are discussed in terms of this information.

Aged↗