Search PubMed⌕ Search

Biomedical subjects

C Owsley

Publications and source records attributed to C Owsley.

At least 37 records · Page 2Linked to original sources
PubMed1998

Driving avoidance and functional impairment in older drivers.

The purpose of this study was to examine the association between visual and cognitive impairment in older drivers and their avoidance of potentially challenging, driving situation. A group of 257 older drivers participated in assessments of visual sensory function, eye health and cognitive function including the useful field of view test, and completed a structured questionnaire on driving exposure and how frequently they avoided challenging driving situations. Results replicated earlier studies showing that many older drivers limit their exposure to driving situations which are generally believed to be more difficult (e.g. rain, night, heavy traffic, rush hour). Furthermore, older drivers with objectively determined visual and/or attentional impairments reported more avoidance than those free of impairments; those with the most impairment reported avoiding more types of situations than other less impaired or non-impaired drivers. Older drivers with a history of at-fault crashes in the prior five years reported more avoidance than those who had crash-free records. Future research should evaluate the potentially beneficial role of self-regulation in enhancing older driver safety, particularly in those older drivers with visual and attentional processing impairments who have elevated crash risk.

Aged↗
PubMed1998

Identifying crash involvement among older drivers: agreement between self-report and state records.

Older drivers have a high crash rate per vehicle mile of travel. Coupled with the growth of the number of older drivers on the road, this has generated interest in the identification of factors which place older drivers at increased risk. However, much of the existing research on medical and functional risk factors for crash involvement has generally been inconsistent. Methodological differences between studies have been hypothesized as being partly responsible for such inconsistencies. The source of information used to identify crash-involved drivers has been identified as one such difference. This paper reports on the agreement between self-report and state record for identifying crash involved-older drivers. We also sought to determine whether the prevalence of visual and cognitive impairment differs across crash-involved drivers identified by either or both sources. Finally, we assessed whether risk factors for crash involvement differed when crash-involved drivers were identified by either self-report or state records. Results indicated that there was a moderate level of agreement between self-reported and state-recorded crash involvement (kappa = 0.45). However, we did find significant differences between crash-involved drivers identified via state records and/or self-report with respect to demographic (age, race), driving (annual mileage, days per week driven), and vision impairment (acuity, contrast sensitivity, peripheral visual field sensitivity, useful field of view). We also found that the possibility for biased measures of association is real. Useful field of view impairment was associated with both self-reported and state-recorded crash involvement; however, the magnitude of the associations was disparate. Moreover, glaucoma was identified as a significant risk factor when considering state-recorded crashes but not self-reported crashes. While validation of these findings is required, research designed to identify risk factors for crash involvement among older drivers should carefully consider the issue of case definition, particularly if self-report is used to identify crash-involved older drivers.

Accidents, Traffic↗
PubMed1998

Aging and scotopic sensitivity.

Scotopic sensitivity was compared in young and older adults in good eye health after individualized correction for age-related changes in lens density and control of pupil diameter. Unlike earlier studies on this topic, fundus photography and a grading scale were used to characterize macular health in the older sample. Twenty-four young adults (mean age 27) and 25 older adults (mean age 70 years) underwent scotopic sensitivity testing after 30 min of dark adaptation. Light sensitivity for a 450 nm target was measured at 4, 7, 32, and 38 degrees both nasally and temporally along the horizontal meridian. Lens density was estimated using Sample's method. On average, older adults exhibited a 0.5 log unit decrease in sensitivity even with lens density taken into account, which did not vary with target eccentricity or nasal/temporal hemifield. Although 60% of older subjects exhibited fundoscopic signs of early age-related maculopathy (ARM), even those free from these signs demonstrated a half log unit sensitivity loss, suggesting that this impairment may represent a biological aging process. We found no psychophysical evidence that scotopic sensitivity loss in older adults with relatively good retinal health is accentuated in the peri-macula, even though anatomical studies on donor retinas from older adults have indicated that this area has heightened rod loss.

Adult↗
PubMed1998

Vision impairment, eye disease, and injurious motor vehicle crashes in the elderly.

The objective of this case-control study was to identify visual risk factors for vehicle crashes by elderly drivers which result in injury. The sample consisted of licensed current drivers between 55 and 87 years of age who resided in Jefferson County, Alabama. Subjects were identified through Alabama Department of Public Safety (ADPS) files. Two groups of cases were identified. One group (N = 78) was defined as those drivers who had incurred at least one vehicle crash between 1985 and 1990 resulting in an injury to anyone in the involved vehicles according to the accident report. The other case group (N = 101) consisted of drivers involved in non-injurious crashes during the same time period. Controls (N = 115), also selected from ADPS files, were older drivers not involved in crashes during the same five-year period. Subjects underwent a battery of visual processing tests and a comprehensive eye examination. The main results were that restricted useful field of view and glaucoma were the only significant independent predictors of injurious crash involvement. Odds ratios (ORs) for reductions in the useful field of view of 23-40%, 41-60% and greater than 60% were 4.2 (95% confidence interval [CI], 1.5-11.8), 13.6 (95% CI, 5.8-39.7), and 17.2 (95% CI, 5.3-55.6), respectively, compared to reductions of less than 23% (p for trend < 0.001). The OR for glaucoma was 3.6 (95% CI, 1.0-12.6). Useful field of view impairment was the only variable independently associated with non-injurious crash involvement. This study implies that impaired visual processing and glaucoma may play a role in the etiology of older driver crashes which result in injury.

Accidents, Traffic↗
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↗