Age and Visual Impairment Decrease Driving Performance as Measured on a Closed-Road Circuit 學生：董瑩蟬

Purpose This paper aim investigated the age and visual impairment for the driver performance declined or not.

Reference Older issues –The older has higher crash accident. (Stamatiadis et al,1995) –The intersections and complex traffic situation that older driver has poor attention, judgment road signs, left turns. (Keltner et al.,1987; McGwin et al,1999; Planek et al,1971)

Reference Visual issues –Visual impairment of the older that increased crashed rates. (Shinar et al,1991) –Visual impairment becomes very prevalent when increased age. (Attebo et al.,1996) –The older light sensitivity, glare sensitivity and visual acuity become poor.( Haegeratrom et al.,1999) –The visual disease increased with increasing age. (Klein et al.,1995)

Reference Visual issues –The driver with cataracts increased crash risk. (Owsley et al.,1999) –The impairments binocular visual, dynamic visual acuity, contrast sensitivity and useful field of view that has poor drive performance. (Johnson et al,1983; Hills et al,1977; Owsley et al.,1998) –Visual impairments effect the drive performance. (Wood,1999)

Method Subjects –139 participants –Required health, driving license, visual acuity (20/40) or better –Participants divide to five group

Site –A closed-road circuit (similar to rural roads) Independent variable –Five group –Visual status Dependent variable –Driving performance –vision Method

Driving performance –Road sign recognition: there are 65 road sign on course, when subject see report to researcher. –Road hazard recognition and avoidance: there are nine locations, when subject see report to researcher, record the report number and number hit. –Gap perception: there are nine pairs traffic cones, six cones gaps were wide enough for driver to pass and three to narrow, record the driver judgments accuracy and ability to pass. –Total driving time: the driver completion 5.1 km test time.

Method Driving performance –Divided attention task: used LEDs light illuminated on windscreen, record the discover number. –Maneuvering: there are nine traffic cones place on straight section. Each cones gap 1.5 car lengths. Record driver completion time and total number hit cone. –Reversing: there are two reverse parking task. The area used four traffic poles build it. They record the completion time and the angle of car within the parking area.

Method Vision –Static acuity: measure using Australian vision Chart 5, measured as the logarithm of the min angle of resolution. The working distance were 3.2 m, each letter seen was scored as log units. –Dynamic acuity: long et al.(1988) described the technique. the target C was display on a white hemispherical arc screen of 1.5 m diameter at a speed of 90 °/s. subject report the location of the gap. –Useful field of view: Wood et al.(1995) method. Targets present for 90ms centrally and peripherally. Record subject number miss of peripherally.

Method Vision –Pelli-Robson letter contrast sensitivity: letter contract sensitivity was used the Pelli-Robson chart(Pelli et al,1988). Each letter record scored 0.05 log unit. –Disability glare: Bailey et al.(1991) used this method. The score get the different visual acuity for the no-glare and glare condition. –Visual fields: Used the method decried by Humphrey fields analyzer. The missed number was record. –Dot motion: the stimuli using a Macintosh II computer (Bullimore et al.,1993).Randomly bright presented on a dark background. Subject report the direction in which the dots moved.

Result-Closed-Road Driving Measures

Figure 1. Mean course time (± standard errors) as a function of group membership (1 = young normals, 2 =middle-aged normals, 3 = older normals, 4 = older mild ocular disease, and 5 = older moderate/severe ocular disease). Figure 2. Mean number of road hazards hit (± standard errors) as a function of group membership (1 =young normals, 2 =middle- aged normals, 3 = older normals, 4 = older mild ocular disease, and 5 = older moderate/severe ocular disease).

Result-Closed-Road Driving Measures Figure 3. Mean overall road driving Z scores (± standard errors) as a function of group membership (1 =young normals, 2 = middle-aged normals, 3 = older normals, 4 = older mild ocular disease, and 5 = older moderate/severe ocular disease).

Result-Vision Measures

Figure 4. Mean letter contrast sensitivity as measured with the Pelli-Robson chart (± standard errors) as a function of group membership (1 =young normals, 2 = middle-aged normals, 3 = older normals, 4 = older mild ocular disease, and 5 = older moderate/severe ocular disease). Figure 5. Mean peripheral errors on the UFOV task (± standard errors) as a function of group membership (1= young normals, 2 = middle- aged normals, 3 = older normals, 4 = older mild ocular disease, and 5 = older moderate/severe ocular disease).

Result-Vision and Driving Performance This study obtains the vision and performance relationship to calculate driving scores. The formula describe below: Score = –0.50(0.14) (motion) – 0.03(0.007) (UFOV) (0.23) (Pelli) –0.007(0.003) (dynamic) – 0.76.

Discussion-driving performance The older driver has fewer road signs recognized than young and middle-aged, similar to Kline et al. (1992) result that the older spent more time to read signs. The older driver spent more time to complete the driver task, similar to Schlag (1993) result that age increased the speed slower.

Discussion-driving performance The divided attention task was effect by age but not the visual impairments, McGwin et al.(1999) result showed the older has problems in complex traffic situation. The perception of gap width effect by age or visual states, similar result to Higgins et al.(1998).

Discussion-Visual Function Visual effect by age or ocular disease. There are more studies showed that.(Long et al.,1990; Wood et al.,1995 an so on.) Visual reduction effect by ocular disease. Similar to Talbot et al.(1998)

Discussion-Vision and Driving Performance Analysis the relationship between vision and driving performance. Burg (1967) has study. This paper found the correlations between performance on Pelli-Robson chart, the UFOV that was found Wood et al.(1993,1995)

Conclusion The older driver has difficult recognized road signs. The older driver complete the driver task more time than younger. The divided attention task was effect by age but not the visual impairments.

Conclusion The perception of gap width effect by age or visual states. Visual effect by age or ocular disease. Visual reduction effect by ocular disease. Driving performance was declined with age and visual impairment.