Measures of visual function and percentage of preferred walking speed in older adults: the Salisbury Eye Evaluation Project

PURPOSE: The purpose of this study was to determine the association of static (visual acuity, visual fields, and contrast sensitivity) and dynamic (dynamic visual acuity and motion threshold) measures of vision with mobility performance on a mobility course with obstacles. METHODS: A cross-sectional population-based study of 1504 persons aged 72 to 92 years enrolled in the third round of the Salisbury Eye Evaluation Project. Standardized examinations were used to test binocular visual acuity, better eye-contrast sensitivity, visual fields, dynamic visual acuity, and motion threshold. Cognitive status was assessed by using the standardized Mini-Mental State Examination. Participants were timed when walking a straight 4-m distance and when walking through a mobility course seeded with obstacles. The percentage of preferred walking speed (PPWS) for each subject was calculated as the ratio of mobility course speed to a 4-m walking speed expressed as a percentage. RESULTS: The mean age of the participants was 78.2 years. The mean 4-m walking speed was 0.82 m/s, whereas the mean mobility course speed was 0.47 m/s. The mean PPWS was 57.1%. All vision variables except visual acuity were associated with PPWS in univariate analyses. Multivariate models found visual fields and the cognitive state to be associated with PPWS. There was no association with dynamic measures of vision. CONCLUSIONS: The mobility performance, as measured by PPWS, was associated with visual fields but not with visual acuity, contrast sensitivity, or dynamic vision measures. Deficits in cognition also play an important role in predicting mobility performance.     

Eye care utilization by older Americans: the SEE Project. Salisbury Eye Evaluation.

OBJECTIVE: To determine eye care utilization patterns among older Americans, particularly characterizing those who sought different types of providers, and the predictive factors for seeking eye care services in general and among those with diabetes and those with visual loss. DESIGN AND PARTICIPANTS: The SEE Project, a population-based survey of 2520 persons aged 65 to 84 in Salisbury, Maryland, provided cross-sectional data on eye care use. Questions on eye care use, demographics, medical history, and other factors were asked on the home interview. MAIN OUTCOME MEASURES: Use of an eye care provider in the previous year, with additional outcomes of use of different types of eye care providers. RESULTS: Blacks were significantly less likely to see any type of eye care provider over 1 year: 50% versus 69% among whites. Those who reported having a vision problem, those with more education, and those in the older age groups were significantly more likely to see either an ophthalmologist or an optometrist. Diabetes and driving a car were predictive factors for seeing an ophthalmologist but not for seeing an optometrist. Self-report of diabetes and eye care problems, and being a current driver, were predictive of seeing an eye care professional among those with visual impairment. CONCLUSIONS: Although blacks are known to be at greater risk for several age-related eye diseases, they are much less likely to see an eye care provider. Interventions that remove barriers to eye care services should be considered.     

Visual field loss increases the risk of falls in older adults: the Salisbury eye evaluation

PURPOSE: Falls are a serious and preventable problem in older adults. Impaired vision has been linked to risk of falls; however, the impact of deficits in specific components of vision on the risk of falls is not well known. METHODS: Data on falls for up to 20 months were provided by 2375 individuals participating in the Salisbury Eye Evaluation (SEE). Visual acuity, contrast sensitivity, visual field, and stereoacuity were tested by using standard measures. To aid in the assessment, each participant recorded falls on a calendar that was sent every month to the SEE clinic. beta-Binomial regression analysis was used. RESULTS: Worse visual field scores were associated with the risk of falling (OR = 1.08 for a 10-point loss of points, 95% CI 1.03-1.13). When both central (相似文献   

Divided visual attention as a predictor of bumping while walking: the Salisbury Eye Evaluation

PURPOSE: The purpose of this study was to determine the association between bumping while walking and divided visual attention, as measured by the useful field of view (UFOV). METHODS: The Salisbury Eye Evaluation is a population-based study of community-dwelling adults, aged 72 to 92 at the third round of data collection. Participants walked a circuitous 32.8-m course, seeded with obstacles, and the number of bumps made while traversing the course was counted. UFOV divided attention score was based on processing speed: the time taken to identify a central target, and the location of a peripheral target simultaneously. Association between number of bumps and UFOV score was assessed in a generalized linear model, with adjustment for vision and attention measures that might explain the UFOV score. RESULTS: Of the 1504 participants in this study, 10.1% did not attempt the mobility course. In a model adjusting for demographic, physical, cognitive and attention, and vision measures, a decrease of 50 ms in processing speed for the divided-attention task was associated with a 4.9% increase (P = 0.004) in number of bumps made over the course. Receiver operating characteristic curves were created for the UFOV and visual field tests, to determine accuracy in detecting those with a high number of bumps. The visual field test had slightly higher area under the curve, but positive predictive value for both tests was low. CONCLUSIONS: The UFOV test of divided attention, as measured by processing speed, independently predicted bumping while walking. These data suggest that poor visual attention is a significant risk factor for bumping while walking.     

Characteristics of discrepancies between self-reported visual function and measured reading speed. Salisbury Eye Evaluation Project Team

PURPOSE: Visual impairment is a risk factor for morbidity in the elderly and is often screened for by self-report. This study evaluates whether there are subsets for whom there is a discrepancy between self-reported and measured function. METHODS: The prevalence of a discrepancy between self-reported difficulty reading a newspaper and measured reading speed was determined in 2520 community-based men and women, aged 65 to 84 years, and the discrepant group characterized by polychotomous regression. RESULTS: Of subjects who reported minimal difficulty reading a newspaper, 10.8% (227/2107) read newsprint-sized text (0.21 degrees) more slowly than 80 words/min, a level previously shown to be necessary for sustained reading. Poor visual acuity, presence of psychiatric symptoms, and less satisfaction with vision were associated with being in the group that read slowly and reported difficulty with reading. Better cognition, better visual acuity, more years of education, white race, and fewer psychiatric symptoms were associated with being in the group that read more quickly and reported minimal difficulty. When reading the text size at which subjects read their fastest, only 2.6% of those with minimal difficulty remained discrepant. These individuals were more likely to have less education, be male, be African American, and have poorer cognitive status than those who did not remain discrepant. CONCLUSIONS: A subset of the elderly population have a substantial discrepancy between self-reported reading difficulty and measured reading speed. In some, this discrepancy may be based on underlying expectations and experiences, and in others it may represent a transition from no visual impairment to visual impairment.     

Patterns of glaucomatous visual field defects in an older population: the Blue Mountains Eye Study

This report aims to describe the frequency of different patterns of visual field loss in open-angle glaucoma (OAG). The Blue Mountains Eye Study examined 3654 persons (aged 49+) during 1992-1994. Humphrey supra-threshold visual fields were performed in 88.9%. Those classified as glaucoma suspects had 30-2 full-threshold fields (9.2%). Of OAG cases (n = 108) with field tests in both eyes (n = 97), unilateral defects were present in 49 (50.5%) and bilateral in 48 (49.5%). Advanced field loss was found in 16 (15.4%) subjects and in 22 (10.9%) eyes, with bilateral loss present in 6 (6.2%) cases. Of all eyes of OAG cases (n = 201), 49 (24.4%) had no defects, 52 (25.9%) upper, 61 (30.3%) lower, and 17 (8.5%) had combined upper and lower loss. Of the upper and lower cases (n = 113), the types of defects included nasal step (36), arcuate (26), nasal plus arcuate (26), and hemispherical defects (25). Of subjects with fields in at least one eye (n = 104), there was a similar proportion in the worse eye of upper defects (28.8%), lower (31.7%), and combined upper and lower (24.0%). Undiagnosed OAG was more frequent in unilateral (65.3%) than bilateral (34.7%) cases (P = 0.003). This study reports the pattern of typical glaucomatous field loss in an older Australian population.     

Visual and Cognitive Predictors of Performance on Brake Reaction Test: Salisbury Eye Evaluation Driving Study

Objectives: Concern for driving safety has prompted research into understanding factors related to performance. Brake reaction speed (BRS), the speed with which persons react to a sudden change in driving conditions, is a measure of performance. Our aim is to determine the visual, cognitive, and physical factors predicting BRS in a population sample of 1425 older drivers. Methods: The Maryland Department of Motor Vehicles roster of persons aged 67–87 and residing in Salisbury, MD, was used for recruitment of the study population. Procedures included the following: habitual, binocular visual acuity using ETDRS charts, contrast sensitivity using a Pelli-Robson chart, visual fields assessed with a 81-point screening Humphrey field at a single intensity threshold, and a questionnaire to ascertain medical conditions. Cognitive status was assessed using a standard battery of tests for attention, memory, visuo-spatial, and scanning. BRS was assessed using a computer-driven device that measured separately the initial reaction speed (IRS) (from light change to red until removing foot from accelerator) and physical response speed (PRS) (removing foot from accelerator to full brake depression). Five trial times were averaged, and time was converted to speed. Results: The median brake reaction time varied from 384 to 5688 milliseconds. Age, gender, and cognition predicted total BRS, a non-informative result as there are two distinct parts to the task. Once separated, decrease in IRS was associated with low scores on cognitive factors and missing points on the visual field. A decrease in PRS was associated with having three or more physical complaints related to legs and feet, and poorer vision search. Vision was not related to PRS. Conclusion: We have demonstrated the importance of segregating the speeds for the two tasks involved in brake reaction. Only the IRS depends on vision. Persons in good physical condition may perform poorly on brake reaction tests if their vision or cognition is compromised.     

Eye movements and reading in glaucoma: observations on patients with advanced visual field loss

Purpose

To investigate the relationship between reading speed and eye movements in patients with advanced glaucomatous visual field (VF) defects and age-similar visually healthy people.

Methods

Eighteen patients with advanced bilateral VF defects (mean age: 71, standard deviation [SD]: 7 years) and 39 controls (mean age: 67, SD: 8 years) had reading speed measured using short passages of text on a computer set-up incorporating eye tracking. Scanpaths were plotted and analysed from these experiments to derive measures of ‘perceptual span’ (total number of letters read per number of saccades) and ‘text saturation’ (the distance between the first and last fixation on lines of text). Another eye movement measure, termed ‘saccadic frequency’ (total number of saccades made to read a single word), was derived from a separate lexical decision task, where words were presented in isolation.

Results

Significant linear association was demonstrated between perceptual span and reading speed in patients (R ²?=?0.42) and controls (R ²?=?0.56). Linear association between saccadic frequency during the LDT and reading speed was also found in patients (R ²?=?0.42), but not in controls (R ²?=?0.02). Patients also exhibited greater average text saturation than controls (P?=?0.004).

Conclusion

Some, but not all, patients with advanced VF defects read slower than controls using short text passages. Differences in eye movement behaviour may partly account for this variability in patients. These patients were shown to saturate lines of text more during reading, which may explain previously-reported difficulties with sustained reading.     

Association between intraocular pressure and loss of visual field in chronic simple glaucoma.

This paper reports the analyses on data from 747 patients with chronic simple glaucoma (CSG) recorded in the King's College Hospital glaucoma data base between January 1970 and February 1985, having a mean follow-up time of 5.1 years (mode 8 years) with the object of determining the relationship of intraocular pressure (IOP) and visual field loss in CSG. A highly significant negative relationship was found between the presenting visual field coefficient (FC) and the untreated IOP (r = -0.26, p = 0.0001) - that is, the higher the IOP on detection, the worse is the visual field. A weak negative correlation was present between the change of FC per year and the treated IOP (r = -0.06), p = less than 0.05). At treated IOPs less than or equal to 18 mmHg visual field loss averaged 0.6 unit per year and for IOPs greater than 18 mmHg the average loss was 1.2 units per year. The data confirm both the importance of a raised IOP in the causation of chronic glaucomatous visual field loss and the importance of reducing the IOP in patients with chronic simple glaucoma.     

Association between intraocular pressure peaks and progression of visual field loss

Little is known about the relation between diurnal variations of intraocular pressure (IOP) and prognosis for glaucomatous visual field damage. The association between apparent progressive loss of visual field and the occurrence of IOP peaks was studied. Pressure peaks were detected by a self-tonometer in the natural environment of patients with glaucoma. The study groups consisted of patients with and without a strong indication of progressive visual field losses, all with IOPs of 22 mm Hg or less obtained in the ophthalmologist's office. Patients apparently undergoing progressive visual field loss were found to have significantly more frequent IOP peaks than patients with stable visual fields. A statistical evaluation indicated that, in a population with a 30% prevalence of progressive loss of visual field, 75% of the patients with peaks have progressive loss and 75% of those without peaks do not have visual field progression. Intraocular pressure peaks were thus shown to have an association with the apparent progression of vision loss independent of the mean IOP. Home tonometry appeared to be a promising tool for identifying patients at increased risk of developing visual field loss who may require intensified follow-up and an alteration in clinical management. However, the present study must be complemented by a prospective study.