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C Owsley

Publications and source records attributed to C Owsley.

At least 19 recordsLinked to original sources
PubMed2006

Plasma apolipoproteins and risk for age related maculopathy.

AIM: To determine if elevated plasma levels of atherogenic and/or anti-atherogenic lipoproteins are risk factors for developing age related maculopathy (ARM). METHODS: In a cross sectional study in a university clinic setting, 129 patients (72 women and 57 men) underwent colour fundus photography, acuity and contrast sensitivity assessment, and electroimmunoassays of plasma apolipoproteins B (apoB) and A-I (apoA-I), the principal proteins of low density and high density lipoproteins, respectively. Maculopathy stage was assigned using the AREDS grading system. RESULTS: Levels of apoB in no ARM, mild, intermediate, and advanced ARM groups were 93.3, 91.8, 95.2, and 98.2 mg/dl, respectively. Levels of apoA-I were 147.4, 148.6, 141.0, and 144.9 mg/dl in the same groups. There was no significant association between these measures, typical for age, and maculopathy stage. CONCLUSION: Although drusen associated with ARM and ageing contain cholesterol and apoB, like the lipid rich core of an atherosclerotic plaque, the results of this study and our previous work in toto make the prospects of a plasma origin for these lesion constituents increasingly untenable. This conclusion is consistent with an emerging hypothesis that a large lipoprotein of intraocular origin is an important pathway for constituent retinal lipid processing and the biogenesis of drusen.

Aged↗
PubMed2006

Is there an association between pre-existing sleep apnoea and the development of glaucoma?

AIM: To determine if sleep apnoea is associated with an increased risk of developing glaucoma. METHODS: This was a nested case-control study. Patients seen at the Veterans Affairs Medical Center (BVAMC) in Birmingham, Alabama, with newly diagnosed glaucoma (cases) between 1997 through 2001 were selected (n = 667) and age matched with non-glaucomatous controls (n = 6667). Patient information was extracted from the BVAMC data files containing demographic, clinical, and medication information. An index date was assigned to the glaucoma subjects corresponding to the time of diagnosis. Patients who had a glaucoma diagnosis before the observation period of the study were excluded. 10 controls were randomly selected for each case and matched on age (plus or minus 1 year) and an encounter on or before the index date of the matched case. Ihe main outcome measures were crude and adjusted relative risks for the association between the previous diagnosis of sleep apnoea and the development glaucoma. Adjustment was performed for the associations of diabetes, lipid metabolism disorders, hypertension, cardiovascular disease, cerebrovascular disease, arterial disease, and migraines. RESULTS: Individuals who developed glaucoma were more likely to have a previous sleep apnoea diagnosis relative to control subjects. However, this finding was of borderline significance at an alpha of 0.05 (p value = 0.06, odds ratio = 2.20, 95% confidence intervals 0.967 to 5.004). Following adjustment for other potential risk factors, no significant difference was seen (p value = 0.18, odds ratio = 1.80, 95% confidence interval 0.76 to 4.23). CONCLUSIONS: This nested case-control study does not support a large impact of sleep apnoea on the eventual development of glaucoma relative to other putative risk factors.

Aged↗
PubMed2006

Non-arteritic anterior ischaemic optic neuropathy and the treatment of erectile dysfunction.

AIM: To determine the association between Viagra (sildenafil) and Cialis (tadalafil) and non-arteritic anterior ischaemic optic neuropathy (NAION). METHODS: A retrospective matched case-control study was conducted. 38 cases of NAION in males were identified from an academic ophthalmology practice in Birmingham, Alabama, and matched (on age) to 38 controls without a history of NAION. Self reported information regarding past and current use of Viagra and/or Cialis was obtained via a telephone questionnaire from interviewers who were not blind to case status. RESULTS: Overall, males with NAION were no more likely to report a history of Viagra or Cialis use compared to similarly aged controls (odd ratio (OR) 1.75, 95% confidence interval (CI) 0.48 to 6.30 and OR 1.82, 95% CI 0.21 to 15.39). However, for those with a history of myocardial infarction, a statistically significant association was observed (OR 10.7, 95% CI 1.3 to 95.8). A similar association was observed for those with a history of hypertension though it lacked statistical significance (OR 6.9, 95% CI 0.8 to 63.6). CONCLUSIONS: For men with a history of myocardial infarction or hypertension the use of Viagra or Cialis may increase the risk of NAION. Physicians prescribing these medications to patients with these conditions should warn them about the potential risk of NAION.

Carbolines↗
PubMed2005

The relation between C reactive protein and age related macular degeneration in the Cardiovascular Health Study.

AIM: To test the hypothesis that individuals with age related macular degeneration (AMD) have increased C reactive protein (CRP) levels. METHODS: A cross sectional study design using data from the Cardiovascular Health Study (CHS), a longitudinal study that enrolled older adults from four communities in the United States from 1989 to 1990, was employed to investigate the existence of an association between AMD and CRP levels in this population. Fundus photographs from 1997 and 1998 were used to identify individuals with (n=390) and without AMD (n=2365). The association between AMD and CRP levels (measured at baseline) was compared, adjusting for the potentially confounding effect of demographic, lifestyle, and health related characteristics. RESULTS: Among the 2755 CHS participants with gradable fundus photographs, 390 were identified as having AMD. Overall, median CRP levels among those with AMD (1.76 mg/l) were similar to those without AMD (1.77 mg/l). CRP levels were categorised into quartiles and compared between those with and without AMD. Relative to those in the lowest quartile (0.07-0.93 mg/l), the odds ratios (OR) in the higher quartiles, adjusted for demographic, lifestyle, and health related characteristics were increased but not statistically significant (0.94-1.77 mg/l: OR=1.14, 95% CI 0.82 to 1.60; 1.78-3.04 mg/l: OR=1.24, 95% CI 0.88 to 1.75; >3.04 mg/l: OR=1.24, 95% CI 0.87 to 1.78). CONCLUSIONS: In the CHS, there is no evidence that CRP levels are associated with AMD. These data do not support the theory alleging non-specific systemic inflammation in the aetiology and natural history of this disease.

Aged↗
PubMed2003

The association between statin use and age related maculopathy.

AIMS: To evaluate the association between age related maculopathy (ARM) and statin use. METHODS: A nested case-control study among patients at the Veterans Affairs Medical Center in Birmingham, Alabama, with newly diagnosed ARM (cases) between 1997 to 2001 were selected and age matched to non-ARM controls. RESULTS: 550 incident cases of ARM were identified and matched to 5500 controls. Overall, cases were 70% (OR 0.30, 95% CI 0.21 to 0.45) less likely to have received and filled a statin prescription relative to the controls. This association was present among both current and past (OR 0.34, 95% CI 0.21 to 0.53 and OR 0.26, 95% CI 0.14 to 0.47, respectively) statin users. When considering use of statin and/or non-statin lipid lowering medications, a significant risk reduction was observed for statin only users (OR 0.30, 95% CI 0.20 to 0.45) and combined statin and non-statin users (OR 0.20, 95% CI 0.06 to 0.64); there was no significant association for non-statin only users (OR 0.47, 95% CI 0.20 to 1.13). CONCLUSIONS: The results of this study suggest that subjects with ARM were significantly less likely to have filled a statin prescription. Future clinical research initiatives should include a clinical trial to provide direct evidence of the effectiveness of statins in lowering the incidence and progression of ARM.

Aged↗
PubMed2001

Visual risk factors for crash involvement in older drivers with cataract.

BACKGROUND: The Impact of Cataracts on Mobility project has previously demonstrated that older drivers with cataract have an elevated risk of motor vehicle collision. OBJECTIVE: To examine what types of visual impairment serve as a basis of the increased crash risk of older drivers with cataract. METHODS AND DESIGN: A cross-sectional analysis was performed on 274 older drivers with cataract and 103 older drivers free of cataract recruited through 12 eye care clinics for the purposes of the Impact of Cataracts on Mobility project, a prospective study on driving mobility in older adults with cataract. Tests measured visual acuity, contrast sensitivity, and disability glare for each eye separately using habitual distance correction. The dependent variable was involvement in at least 1 state-recorded, at-fault vehicle crash during the 5 years prior to study enrollment. RESULTS: Logistic regression evaluated associations (odds ratios [ORs]) between visual function and crash involvement. Better and worse eye models defined on the basis of visual acuity were developed. Associations between each type of visual function and crash involvement were adjusted for age, sex, driving exposure, cognitive status, and other types of visual function. For both the better and worse eye models, contrast sensitivity was independently associated with crash involvement, whereas visual acuity and disability glare were not. Drivers with a history of crash involvement were 8 times more likely to have a serious contrast sensitivity deficit in the worse eye (defined as a Pelli-Robson score of 1.25 or less) than those who were crash-free (OR = 7.86; 95% confidence interval [CI], 1.55-39.79); this association was weaker for the better eye but still statistically significant (OR = 3.78; 95% CI, 1.15-12.48). Crash-involved drivers were 6 times more likely to have severe contrast sensitivity impairment in both eyes (OR = 5.78; 95% CI, 1.87-17.86) than crash-free drivers. A severe contrast sensitivity deficit in only 1 eye was still significantly associated with crash involvement (OR = 2.70; 95% CI, 1.16-6.51). CONCLUSION: Severe contrast sensitivity impairment due to cataract elevates at-fault crash risk among older drivers, even when present in only 1 eye.

Accidents, Traffic↗
PubMed2001

Delays in rod-mediated dark adaptation in early age-related maculopathy.

OBJECTIVE: To determine whether there are disturbances in the rod-mediated kinetics of dark adaptation in early age-related maculopathy (ARM). DESIGN: Comparative, observational case series. PARTICIPANTS: Twenty older adults with early ARM as defined by one or more large (> 63 microm) drusen, focal hyperpigmentation, or both, but no choroidal neovascularization or geographic atrophy, and 16 adults in the same age range with none of these fundus features. All participants had 20/25 visual acuity or better in the tested eye. METHODS: Dark adaptation functions were measured using a modified Humphrey Field Analyzer (Zeiss Humphrey Systems, Dublin, CA) to assess the rate of rod-mediated sensitivity recovery at 12 degrees on the vertical meridian in the inferior visual field after exposure to the equivalent of a 98% bleach. Baseline (prebleach) scotopic sensitivity, visual acuity, contrast sensitivity, and photopic sensitivity were also measured. MAIN OUTCOME MEASURES: Rod-cone break; second and third components of rod-mediated dark adaptation; time to baseline sensitivity; and baseline (prebleach) scotopic sensitivity. RESULTS: Although their visual acuity was at least 20/25, patients with early ARM on average exhibited deficits in almost all rod-mediated parameters of dark adaptation as compared with age-similar healthy participants. For example, the rod-cone break was delayed approximately 10 minutes in early ARM patients as compared with healthy participants. Age-related maculopathy patients were more likely to fall outside the normal reference range for variables representing dark adaptation kinetics than for steady-state visual functions such as scotopic sensitivity. For example, 85% of ARM patients fell outside the normal reference range in at least one dark adaptation kinetic parameter, whereas only 25% of ARM patients fell outside the normal reference range for steady-state scotopic sensitivity. CONCLUSIONS: Rod-mediated kinetic parameters of dark adaptation, which reflect the sensitivity recovery of the visual cycle, are disrupted early in ARM pathogenesis.

Aged↗
PubMed2001

Timed instrumental activities of daily living tasks: relationship to visual function in older adults.

PURPOSE: To identify instrumental activities of daily living (IADL) tasks whose completion time is related to visual function in older adults. METHODS: Visual function (acuity, contrast sensitivity, and useful field of view) and the time to complete 17 visual tasks of everyday life were measured in a sample of 342 older adults (mean age 71 years, range 56 to 86) recruited from eye clinics. The timed IADL (TIADL) tasks included a variety of visual activities such as reading ingredients on cans of food and instructions on medicine bottles, finding a phone number in a directory, locating items on a crowded shelf and in a drawer, and using a screwdriver. RESULTS: Multiple regression analysis indicated that poorer scores for acuity, contrast sensitivity, and useful field of view were independently associated with longer times to complete visual TIADL tasks, even after adjusting for age, educational level, depression, and general health. Cognitive status also had a significant, independent association with timed task performance. CONCLUSIONS: Older adults' timed performance in everyday tasks is related to various aspects of visual function independent of the influences of other functional and health problems and advanced age. This suggests that TIADL tasks may eventually be useful as performance outcomes in intervention evaluations targeted at reversing vision impairment or minimizing its impact. To understand the relationship between vision impairment and TIADL task performance in older adults, cognitive impairment needs to be taken into account because it has a relatively strong and independent relationship with visual TIADL task performance.

Activities of Daily Living↗
PubMed2000

Visual risk factors for driving difficulty among older drivers.

This study sought to evaluate associations between visual function and self-reported difficulty with driving tasks. Drivers (N = 384) between the ages of 55 and 85 were selected from ophthalmology practices and optometry clinics; three out of four of the sample had cataracts and the remaining were cataract-free. Information on driving exposure and difficulty was obtained via self-report. Visual functional status of all participants was measured with respect to acuity, contrast sensitivity, disability glare and useful field of view. Cognitive impairment was evaluated using the Mattis Organic Mental Syndrome Screening Examination. The results show a pattern of difficulty in high-risk driving situations among those with decreased visual acuity and contrast sensitivity, even after adjustments for age, gender, weekly mileage, and cognitive impairment.

Age Factors↗
PubMed2000

Scotopic sensitivity during adulthood.

Older adults typically exhibit about a half log unit loss in scotopic sensitivity that cannot be attributed to optical factors and retinal disease suggesting a neural origin. Little is understood about the developmental course of this neural deficit as to whether it first appears in late life or gradually emerges during the course of adulthood. To address this developmental issue, scotopic sensitivity was measured in 94 adults ranging in age from the 20s to the 80s. Thresholds were measured at 27 test loci within a 18 degrees radius field. Analogous measurements were made for photopic sensitivity. Fundus photography and a grading scale were used to characterize macular health in subjects over age 49 in order to control for macular disease. Scotopic sensitivity decreased at a rate of 0.08 log units per decade; this decline was better fit by a single line model, not a bilinear model, implying that the impairment does not suddenly emerge in late life but gradually appears over the course of adulthood. Photopic sensitivity also decreased in a linear fashion at a rate of 0.04 log units per decade. Under these test conditions, the rate of scotopic sensitivity decline during adulthood was about double the rate of photopic sensitivity decline.

Adult↗
PubMed2000

Exploratory study of incident vehicle crashes among older drivers.

BACKGROUND: As the number of older adult drivers increases, distinguishing safe from unsafe older adult drivers will become an increasing public health concern. We report on the medical and functional factors associated with vehicle crashes in a cohort of Alabama drivers, 55 years old and older. METHODS: This prospective study involved 174 older adults, on whom demographic, medical, functional, and physical performance data were collected in 1991. Subjects were then followed through 1996 for incident vehicle crashes. RESULTS: Sixty-one subjects experienced between one and four police-reported vehicle crashes during the study period. Following adjustment for age, race, days driven per week, and gender, Cox proportional-hazards models showed the following variables to be associated with crash involvement: reported difficulty with yardwork or light housework (relative risk [RR] = 2.1; 95% confidence interval [CI] 1.1, 4.0; p = .02), or opening ajar (RR = 3. 1; 95% CI 1.4, 6.7; p = .004); at least one crash before 1991 (RR = 2.1; 95% CI 1.2, 3.7; p = .008); using hypnotic medication (RR = 2.9; 95% CI 1.3, 6.6; p = .01); self-reported stroke or transient ischemic attack (RR = 2.7; 95% CI 1.1, 6.6; p = .03); scoring within the depressed range on the Geriatric Depression Scale (RR = 2.5; 95% CI 1.1, 6.0; p = .03), and failing the useful field-of-view test (RR = 1.9; 95% CI 1.0, 3.5; p = .05). CONCLUSIONS: Variables related to function, medication use, affect, neurological disease, and visuocognitive skills were associated with vehicle crash involvement in this cohort. Our findings suggest that multifactorial assessments are warranted to identify at-risk older drivers.

Accidents, Traffic↗
PubMed2000

Psychophysical evidence for rod vulnerability in age-related macular degeneration.

PURPOSE: To determine whether there is rod system dysfunction in the central retina of patients with age-related macular degeneration (AMD). METHODS: Dark-adapted sensitivity (500-nm stimulus) and light-adapted sensitivity (600 nm) were measured psychophysically at 52 loci in the central 38 degrees (diameter) of retina in 80 patients with AMD, and results were compared with those from older adult normal controls. All dark-adapted data were corrected for preretinal absorption. RESULTS: Mean field dark-adapted sensitivity was significantly lower in AMD patients as a group than in normal subjects. Within the AMD group were subsets of patients with normal mean dark- and light-adapted sensitivities; reduced dark-adapted sensitivities without detectable light-adapted losses; both types of losses; and, least commonly, only light-adapted losses. Regional retinal analyses of the dark-adapted deficit indicated the greatest severity was 2 degrees to 4 degrees or approximately 1 mm from the fovea, and the deficit decreased with increasing eccentricity. CONCLUSIONS: These psychophysical results are consistent with histopathologic findings of a selective vulnerability for parafoveal rod photoreceptors in AMD. The different patterns of rod and cone system losses among patients at similar clinical stages reinforces the notion that AMD is a group of disorders with underlying heterogeneity of mechanism of visual loss. Dark-adapted macula-wide testing may be a useful complement to the more traditional outcome measures of fundus pathology and foveal cone-based psychophysics in future AMD trials.

Aged↗
PubMed1999

Aging and dark adaptation.

Older adults have serious difficulty seeing under low illumination and at night, even in the absence of ocular disease. Optical changes in the aged eye, such as pupillary miosis and increased lens density, cannot account for the severity of this problem, and little is known about its neural basis. Dark adaptation functions were measured on 94 adults ranging in age from the 20s to the 80s to assess the rate of rod-mediated sensitivity recovery after exposure to a 98% bleach. Fundus photography and a grading scale were used to characterize macular health in subjects over age 49 in order to control for macular disease. Thresholds for each subject were corrected for lens density based on individual estimates, and pupil diameter was controlled. Results indicated that during human aging there is a dramatic slowing in rod-mediated dark adaptation that can be attributed to delayed rhodopsin regeneration. During the second component of the rod-mediated phase of dark adaptation, the rate of sensitivity recovery decreased 0.02 log unit/min per decade, and the time constant of rhodopsin regeneration increased 8.4 s/decade. The amount of time to reach within 0.3 log units of baseline scotopic sensitivity increased 2.76 min/decade. These aging-related changes in rod-mediated dark adaptation may contribute to night vision problems commonly experienced by the elderly.

Adult↗
PubMed1999

Older drivers and cataract: driving habits and crash risk.

BACKGROUND: Cataract is a leading cause of vision impairment in older adults, affecting almost half of those over age 75 years. Driving is a highly visual task and, as with other age groups, older adults rely on the personal automobile for travel. The purpose of this study was to examine the role of cataract in driving. METHODS: Older adults (aged 55-85 years) with cataract (n = 279) and those without cataract (n = 105) who were legally licensed to drive were recruited from eye clinics to participate in a driving habits interview to assess driving status, exposure, difficulty, and "space" (the distance of driving excursions from home base). Crash data over the prior 5 years were procured from state records. Visual functional tests documented the severity of vision impairment. RESULTS: Compared to those without cataract, older drivers with cataract were approximately two times more likely to report reductions in days driven and number of destinations per week, driving slower than the general traffic flow, and preferring someone else to drive. Those with cataract were five times more likely to have received advice about limiting their driving. Those with cataract were four times more likely to report difficulty with challenging driving situations, and those reporting driving difficulty were two times more likely to reduce their driving exposure. Drivers with cataract were 2.5 times more likely to have a history of at-fault crash involvement in the prior 5 years (adjusted for miles driven/week and days driven/week). These associations remained even after adjustments for the confounding effects of advanced age, impaired general health, mental status deficit, or depression. CONCLUSIONS: Older drivers with cataract experience a restriction in their driving mobility and a decrease in their safety on the road. These findings serve as a baseline for our ongoing study evaluating whether improvements in vision following cataract surgery expand driving mobility and improve driver safety.

Accidents, Traffic↗
PubMed1999

Using nonlinear regression to estimate parameters of dark adaptation.

An objective technique for estimating the kinetics of dark adaptation is presented, with which one can evaluate models with multiple parameters, evaluate several models of dark adaptation simultaneously, and rapidly analyze large data sets. Another advantage is the ability to simultaneously estimate transition times and rates of sensitivity recovery. Finally, this nonlinear regression technique does not require that the distributional properties of the data be transformed, and thus, parameter estimates are in meaningful units and reflect the actual rate of recovery of sensitivity.

Adult↗
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↗