The purpose of the study was (1) to determine thresholds for discriminating speed in peripheral fields of patients with dry AMD and (2) to examine the driving skills of licensed drivers with early dry AMD using a driving simulator and to investigate how their healthy counterparts perform on the same driving tasks. We hypothesized that speed discrimination may be better in patients with dry AMD than in healthy control subjects.
This observational study has two goals: 1. to establish if patients affected by dry AMD have a different speed discriminating threshold using peripheral vision fields than their healthy counterparts. 2. to determine if the driving skills of AMD and glaucoma patients differ from healthy controls. Two tasks will be used: 1) A speed discrimination test. (Glaucoma patient are not asked to perform this task as it assesses the peripheral visual fields, which is affected by the disease.) 2) A driving simulation session. Participant will undergo both tests on the same day, no later than a month after the initial recruitement visit. For both diseases, patients will be compared to healthy controls matched for age and gender, but also to a younger control group. The latter group was added in order to take into account the normal aging impact on driving skills (visual and cognitive). Our hypothesis is that AMD patient will show a better speed discriminating threshold than matched control and maybe better or equal to the younger control groups. We also hypothesize that driving skills involving peripheric speed awareness, such as passing another car, will be enhanced in the AMD group when compared to glaucoma patients and age-matched control group.
Study Type
OBSERVATIONAL
Enrollment
60
The participant has to stare in the middle of two screens, i.e the reference screen and the test screen. Dots are moving from the center to the edge of the screens at different speeds. The participant is forced to determine if the dots of the test screen are moving faster or slower than the reference screen. The test is designed in Psychtoolbox3. Data analyses performed using MATLAB. Two-alternative forced choice paradigm.
25 km simulated car driving session. The participant is seated in the driver compartment of a real car featuring all the actual components (steering wheel, pedals regulating speed and brakes). He is instructed to respect road regulations as well as safety rules and must perform some driving manoeuvres, such has turning at intersections, stopping when necessary, passing another car, etc. Software Drive 3.0 by Systems Technology Inc., Hawthorne, California, USA. Magnetic head tracker (Flock of Birds, Ascension Technology Corporation, Burlington, Vermont, USA). A fixed-base driving simulator. 2 driving scenarios: a practice (10 minutes) and a main scenario including rural and urban sections (35 minutes).
Centre universitaire d'ophtalmologie, Hôpital du Saint-Sacrement, CHU de Québec
Québec, Quebec, Canada
Speed discrimination threshold
75% point is taken as a measure of the discrimination threshold.
Time frame: Before driving simulation
Driving performance
Probe reaction time task. Speed limits. Respect of traffic safety rules.
Time frame: After speed discrimination task
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