Biomedical subjects

Joanne M Wood

Publications and source records attributed to Joanne M Wood.

16 recordsLinked to original sources

PubMed2006

Predictors of driving assessment outcome in Parkinson's disease.

This study evaluated selected clinical and functional tests as predictors of driving safety outcomes in Parkinson's disease (PD) patients. A total of 25 PD patients and 21 age-matched controls, all regular drivers, underwent neurological evaluation and assessment of cognitive, visual, and motor function and a standardized, on-road driving assessment. The capacity of the tests to predict pass/fail driving outcomes was determined by selecting a subset with the highest predictive value from each domain and then subjecting these subsets to discriminant function analysis. Accuracy, sensitivity, specificity, and positive and negative predictive values were determined. Three relatively simple tests from the larger battery predicted passes with relatively high sensitivity (PD, 72.7%; controls, 93.8%; both combined, 85.2%); and moderate specificity (PD, 64.3%; controls, 60.0%; both combined. 63.2%). These tests assessed motor performance (Purdue Pegboard test), contrast sensitivity (Pelli-Robson test), and cognitive function (verbal version of Symbol Digit Modalities test). Adding time since diagnosis for the PD group increased sensitivity to 90.9% and specificity to 71.4%. These simple tests confer more objectivity and predictive power to clinical recommendations for driving, they reflect distinct functions that are necessary for safe driving, and they may be especially useful when on-road assessments are not feasible.

Activities of Daily Living↗

PubMed2006

Reflexive optokinetic nystagmus in younger and older observers under photopic and mesopic viewing conditions.

PURPOSE: To investigate the effect of age on optokinetic nystagmus (OKN) in response to stimuli designed to preferentially stimulate the M-pathway. METHOD: OKN was recorded in 10 younger (32.3 +/- 5.98 years) and 10 older (65.6 +/- 6.53) subjects with normal vision. Vertical gratings of 0.43 or 1.08 cpd drifting at 5 degrees /s or 20 degrees /s and presented at either 8% or 80% contrast were displayed on a large screen as full-field stimulation, central stimulation within a central Gaussian-blurred window of 15 degrees diameter, or peripheral stimulation outside this window. All conditions apart from the high-contrast condition were presented in a random order at two light levels, mesopic (1.8 cdm(-2)) and photopic (71.5 cdm(-2)). RESULTS: Partial-field data indicated that central stimulation, mesopic light levels, and lower temporal frequency each significantly increased slow-phase velocity (SPV). Although there was no overall difference between groups for partial-field stimulation, full-field stimulation, or low-contrast stimulation, a change in illumination revealed a significant interaction with age: there was a larger decrease in SPV going from photopic to mesopic conditions for the older group than the younger group, especially for higher temporal frequency stimulation. CONCLUSIONS: OKN becomes reflexive in conditions conducive to M-pathway stimulation, and this rOKN response is significantly diminished in older healthy adults than in younger healthy adults, indicative of decreased M-pathway sensitivity.

Adult↗

PubMed2005

Effects of age and auditory and visual dual tasks on closed-road driving performance.

PURPOSE: This study investigated how driving performance of young and old participants is affected by visual and auditory secondary tasks on a closed driving course. METHODS: Twenty-eight participants comprising two age groups (younger, mean age = 27.3 years; older, mean age = 69.2 years) drove around a 5.1-km closed-road circuit under both single and dual task conditions. Measures of driving performance included detection and identification of road signs, detection and avoidance of large low-contrast road hazards, gap judgment, lane keeping, and time to complete the course. The dual task required participants to verbally report the sums of pairs of single-digit numbers presented through either a computer speaker (auditorily) or a dashboard-mounted monitor (visually) while driving. Participants also completed a vision and cognitive screening battery, including LogMAR visual acuity, Pelli-Robson letter contrast sensitivity, the Trails test, and the Digit Symbol Substitution (DSS) test. RESULTS: Drivers reported significantly fewer signs, hit more road hazards, misjudged more gaps, and increased their time to complete the course under the dual task (visual and auditory) conditions compared with the single task condition. The older participants also reported significantly fewer road signs and drove significantly more slowly than the younger participants, and this was exacerbated for the visual dual task condition. The results of the regression analysis revealed that cognitive aging (measured by the DSS and Trails test) rather than chronologic age was a better predictor of the declines seen in driving performance under dual task conditions. An overall z score was calculated, which took into account both driving and the secondary task (summing) performance under the two dual task conditions. Performance was significantly worse for the auditory dual task compared with the visual dual task, and the older participants performed significantly worse than the young subjects. CONCLUSIONS: These findings demonstrate that multitasking had a significant detrimental impact on driving performance and that cognitive aging was the best predictor of the declines seen in driving performance under dual task conditions. These results have implications for use of mobile phones or in-vehicle navigational devices while driving, especially for older adults.

Adult↗

PubMed2005

Predicting components of closed road driving performance from vision tests.

PURPOSE: Mild cataracts can interfere with visually dependent everyday activities, although they only minimally affect static visual acuity. This study compared the effects of simulated cataracts with that of optical blur on driving performance and determined the extent to which acuity could account for variations in driving performance either alone or in combination with supplementary vision tests. METHODS: Closed road driving performance was measured in 24 young, normally sighted subjects under five binocular acuity levels, four produced by different levels of optical blur (6/4.5, 6/12, 6/30, 6/60) and one by frosted lenses simulating mild cataracts (6/12c). Driving measures included gap perception, total driving time, sign recognition, road hazard avoidance, maneuvering time, and errors. Subjects were also tested with the Pelli-Robson chart, SKILL card, and Berkeley Glare Test under comparable acuity levels. RESULTS: Total driving time, sign recognition, and hazard avoidance were linearly related to the acuity degradation produced by blur; performance in the 6/12c condition was similar to that in the 6/60 blur condition. Static acuity predicted 30% to 60% of the variance in these driving measures when the 6/12c condition was excluded from analysis; this proportion was reduced by a factor of two to three when the 6/12c condition was included. However, using any one of the three supplementary tests with visual acuity in a multiple regression analysis recaptured much of the lost variance. CONCLUSIONS: Static acuity can only predict variations in closed road driving performance measured under degraded conditions that include simulated mild cataracts when it is combined with supplementary vision tests.

Adult↗

PubMed2005

Standard measures of visual acuity do not predict drivers' recognition performance under day or night conditions.

PURPOSE: This study investigated whether visual acuity or contrast sensitivity, measured under a range of luminance conditions, could predict drivers' recognition performance under real-world day and night road conditions. METHODS: Twenty-four participants, comprising three age groups (younger, mean = 21.5 years; middle-aged, mean = 46.6 years; and older, mean = 71.9 years), drove around a 1.8-km closed road circuit under day and nighttime conditions. At night, headlight intensity was varied over 1.5 log-units by ND filters mounted on the headlights. Participants drove around the circuit under five light conditions (daytime and four at night) and were asked to report relevant targets, including road signs, large low-contrast road obstacles, and pedestrians who wore retroreflective markings on either the torso or the limb joints (creating "biological motion"). Real-world recognition performance was measured as percent correct recognition and, in the case of low-contrast road obstacles, avoided. Clinical vision tests included high-contrast visual acuity and Pelli-Robson letter contrast sensitivity measured at four luminance levels. RESULTS: Real-world recognition performance of all age groups was significantly degraded under low light conditions, and this impairment was greater for the older participants. These changes in drivers' recognition performance were more strongly predicted by contrast sensitivity than visual acuity measured under standard photopic conditions. Interestingly, contrast sensitivity was highly correlated with visual acuity measured under low-luminance conditions. Further analyses showed that recognition performance while driving is better predicted by combinations of two tests: either 1) photopic visual acuity and photopic contrast sensitivity, or 2) photopic and mesopic visual acuity. CONCLUSIONS: These findings confirm that visibility is seriously degraded during night driving and that the problem is greater for older drivers. These changes in real-world recognition performance were better predicted by a standard test of contrast sensitivity than by visual acuity. Still better predictions can be obtained by the use of two vision tests. The implications of these findings for driver licensing standards are discussed.

Adult↗

PubMed2005

Central visual field changes using flicker perimetry in type 2 diabetes mellitus.

PURPOSE: To evaluate the efficacy of flicker perimetry compared with that of static perimetry in determining central visual field losses in participants with type 2 diabetes mellitus. METHODS: Flicker and static perimetry were performed using the Medmont field analyser on 20 participants with type 2 diabetes mellitus and 24 age-matched control participants. RESULTS: Flicker, but not static, perimetry demonstrated significant reductions in thresholds in those participants who had a recent diagnosis of diabetes or who had no or only minimal diabetic retinopathy compared to the control group at eccentricities close to fixation. CONCLUSION: Flicker perimetry is recommended for the evaluation of visual field losses in participants with recent onset of diabetes and minimal diabetic retinopathy.

Aged↗

PubMed2005

When red lights look yellow.

PURPOSE: Red signals are typically used to signify danger. This study was conducted to investigate a situation identified by train drivers in which red signals appear yellow when viewed at long distances (approximately 900 m) through progressive-addition lenses. METHODS: A laboratory study was conducted to investigate the effects of defocus, target size, ambient illumination, and surround characteristics on the extent of the color misperception of train signals by nine visually normal participants. The data from the laboratory study were validated in a field study by measuring the amounts of defocus and the distances at which the misperception of the color of train signals was apparent and whether these distances varied as a function of time of day. RESULTS: The laboratory study demonstrated that small red targets (approximately 1 min arc) can appear yellow when viewed through small amounts of defocus (approximately +0.75 D) under bright illumination (1910 cd/m(2)). In the field study, the defocus needed to produce the color misperception was similar to that found in the laboratory study. Time of day affected the color misperception, and there was no misperception at night. CONCLUSIONS: The color misperception is not solely associated with progressive-addition lenses, but occurs in the presence of small amounts of positive defocus. The potential for the misperception to result in collisions and fatalities presents a major safety concern.

Adult↗

PubMed2005

Limitations in drivers' ability to recognize pedestrians at night.

This study quantified drivers' ability to recognize pedestrians at night. Ten young and 10 older participants drove around a closed road circuit and responded when they first recognized a pedestrian. Four pedestrian clothing and two beam conditions were tested. Results demonstrate that driver age, clothing configuration, headlamp beam, and glare all significantly affect performance. Drivers recognized only 5% of pedestrians in the most challenging condition (low beams, black clothing, glare), whereas drivers recognized 100% of the pedestrians who wore retroreflective clothing configured to depict biological motion (no glare). In the absence of glare, mean recognition distances varied from 0.0 m (older drivers, low beam, black clothing) to 220 m (722 feet; younger drivers, high beam, retroreflective biomotion). These data provide new motivation to minimize interactions between vehicular and pedestrian traffic at night and suggest garment designs to maximize pedestrian conspicuity when these interactions are unavoidable.

Adult↗

PubMed2004

On-road measures of pedestrians' estimates of their own nighttime conspicuity.

PROBLEM: Most pedestrian fatalities occur at night. Although researchers have long understood that drivers have difficulty seeing pedestrians at night and that reflective clothing can dramatically enhance pedestrian conspicuity, the extent to which pedestrians understand these facts is unclear. This experiment quantified pedestrians' estimates of the ability of an approaching driver to recognize the presence of roadside pedestrians. METHOD: Ten younger and 10 older participants walked in place on the far shoulder of a closed-road circuit and pressed a button when they were confident that the approaching driver could first recognize that a pedestrian was present. RESULTS: Pedestrians overestimated their visibility and dramatically underestimated the benefit of conspicuity treatments. CONCLUSIONS: These results suggest that pedestrians fail to understand the magnitude of the nighttime conspicuity problem and the value of conspicuity treatments. Pedestrians may therefore unknowingly place themselves in danger at night. IMPACT: These results underscore the need to educate pedestrians about the dangers of interacting with traffic at night and about treatments that increase their safety.

Accidents, Traffic↗

PubMed2003

Letter contrast sensitivity changes in early diabetic retinopathy.

PURPOSE: To investigate the discriminative ability of letter contrast sensitivity (CS) and visual acuity (VA) in detecting functional losses in participants with type 2 diabetes. METHODS: LogMAR VA and letter CS were measured on 20 type 2 diabetic and 24 age-matched control participants. The diabetic participants were sub-grouped according to the level of retinopathy present. RESULTS: Letter CS was able to distinguish those participants with and without macular oedema and those with no or minimal diabetic retinopathy from the control group, whereas VA was not. CONCLUSION: Letter CS may be used as an effective screening tool to assess damage to the visual pathway of diabetic participants both with and without clinically detectable signs.

Adult↗

PubMed2003

Traffic signal color recognition is a problem for both protan and deutan color-vision deficients.

We investigated the effect of color-vision deficiency on reaction times and accuracy of identification of traffic light signals. Participants were 20 color-normal and 49 color-deficient males, the latter divided into subgroups of different severity and type. Participants performed a tracking task. At random intervals, stimuli simulating standard traffic light signals were presented against a white background at 5 degrees to right or left. Participants identified stimulus color (red/yellow/green) by pressing an appropriate response button. Mean response times for color normals were 525, 410, and 450 ms for red, yellow, and green lights, respectively. For color deficients, response times to red lights increased with increase in severity of color deficiency, with deutans performing worse than protans of similar severity: response times of deuteranopes and protanopes were 53% and 35% longer than those of color normals. A similar pattern occurred for yellow lights, with deuteranopes and protanopes having increased response times of 85% and 53%, respectively. For green lights, response times of all groups were similar. Error rates showed patterns similar to those of response times. Contrary to previous studies, deutans performed much worse than protans of similar severity. Actual or potential applications of this research include traffic signal design and driver licensing.

Accidents, Traffic↗

PubMed2002

Aging, driving and vision.

Older people constitute the fastest growing sector of the driving population and are believed to represent a high risk to road safety, given their high crash rate per distance travelled. The crash characteristics of the elderly also differ from those of younger drivers and generally involve multiple vehicles and more complex driving situations. Although the reasons for this deterioration in driving performance are multi-factorial, the age-related changes in vision are likely to be a significant factor, given the important role of vision in driving. This paper provides an overview of some of the complex issues associated with older drivers and considers how the aging changes in visual function might impact on driving performance. Particular emphasis is placed on the literature linking vision to driving, with emphasis on more recent research. The implications of this research for driver licensing and self-regulation of older drivers are also discussed.

Accidents, Traffic↗

PubMed2002

Age and visual impairment decrease driving performance as measured on a closed-road circuit.

In this study the effects of visual impairment and age on driving were investigated and related to visual function. Participants were 139 licensed drivers (young, middle-aged, and older participants with normal vision, and older participants with ocular disease). Driving performance was assessed during the daytime on a closed-road driving circuit. Visual performance was assessed using a vision testing battery. Age and visual impairment had a significant detrimental effect on recognition tasks (detection and recognition of signs and hazards), time to complete driving tasks (overall course time, reversing, and maneuvering), maneuvering ability, divided attention, and an overall driving performance index. All vision measures were significantly affected by group membership. A combination of motion sensitivity, useful field of view (UFOV), Pelli-Robson letter contrast sensitivity, and dynamic acuity could predict 50% of the variance in overall driving scores. These results indicate that older drivers with either normal vision or visual impairment had poorer driving performance compared with younger or middle-aged drivers with normal vision. The inclusion of tests such as motion sensitivity and the UFOV significantly improve the predictive power of vision tests for driving performance. Although such measures may not be practical for widespread screening, their application in selected cases should be considered.

Adult↗

PubMedDate not supplied

The effect of monovision contact lens wear on driving performance.

BACKGROUND: A number of studies have highlighted the problems with driving reported by wearers of monovision contact lens corrections. In this study, we wished to investigate this further, by determining whether driving performance as measured on the open road under daytime conditions is worse when drivers wear their monovision contact lenses compared to their habitual correction. METHODS: Thirteen subjects with healthy eyes and corrected visual acuity of 6/6 were selected. Each had worn monovision contact lenses for at least three months. All subjects had their driving performance assessed while driving their own vehicles on an open road course, with both monovision contact lenses and their other habitual correction (spectacles or unaided). RESULTS: No statistically significant differences were found in driving performance when subjects wore their monovision contact lenses compared to when they wore their habitual distance correction. CONCLUSIONS: The results indicate that monovision does not adversely affect driving performance in daylight hours for adapted wearers. However, limitations in the study design are acknowledged, including the relatively small sample size, lack of standardisation of the habitual correction and the use of adapted wearers. Future studies are recommended to investigate these issues further.

Journal Article↗

PubMedDate not supplied

Visual fields in glaucoma: a clinical overview.

Static automated visual field testing is now an integral part of the detection and monitoring of primary open angle glaucoma. However, although many aspects of testing are automated, interpretation of the large amounts of data produced by these instruments is not. Two major challenges facing the practitioner are differentiating between the visual fields of a patient with early glaucoma and those of a normal patient, and identifying whether small reductions in sensitivity are due to a true defect or a product of other factors. This paper presents a clinical overview of how to systematically review visual field plots and how to recognise defects arising from patient factors, as well as some of the alternative testing techniques available for the assessment of the glaucoma patient.

Journal Article↗

PubMedDate not supplied

Occupational therapy assessment of open-road driving performance: validity of directed and self-directed navigational instructional components.

OBJECTIVE: The purpose of this study was to validate an assessment tool used by occupational therapists to evaluate on-road driving performance. METHODS: The driving assessment was conducted over a 15-km route that consisted of a range of traffic situations and contained both directed and self-directed navigational instruction. The driving performance of four groups of drivers of different ages and visual characteristics was assessed independently by an occupational therapist and driving instructor using a range of scoring criteria. RESULTS: The occupational therapist scores were significantly affected by the drivers' age and visual characteristics (directed navigation, F(3,133) = 6.05, p = 0.001; self-directed navigation, F(3,133) = 5.04, p < 0.002), and these group differences were greater for self-directed navigational instruction. The occupational therapist scores were highly correlated with the driving instructor's global driver safety rating (r = 0.76, p < 0.001). DISCUSSION: The driving assessment instrument was a valid measure of on-road driving performance relative to an independent global driving safety evaluation. The instrument provided detailed information regarding driving performance and highlighted areas of difficulty, particularly when drivers followed self-navigational instruction.

Adult↗