Driving with central field loss III: vehicle control

Abstract

Background

Visual impairment associated with central field loss may make vehicle control more difficult due to the degraded view of the road. We evaluated how central field loss affects vehicle control in a driving simulator.

Methods

Nineteen participants with binocular central field loss (acuity 6/9 to 6/60) and 15 controls with normal vision drove 10 scenarios, each about eight to 12-minutes. Speed, lane offset and steering wheel reversal rate were measured on straights, left and right curves, along city (approximately 50-km/h) and rural highway (approximately 100-km/h) routes. Following distance was measured on two city straight segments.

Results

Subjects with central field loss had higher steering wheel reversal rates (0.55 versus 0.45 reversals per second, p = 0.015), suggesting that the steering task was more demanding for them, requiring more steering corrections; however, they did not differ in other performance measures. Nearly all maintained a safe following distance, although they were more likely than controls with normal vision to lose sight of the lead car in scenarios that required following a car.

Conclusions

Most measures of vehicle control did not significantly differ between participants with central field loss and those with normal vision; however, the higher steering wheel reversal rates suggest that, in compensating for their vision impairment, drivers with central field loss had to allocate extra steering effort to maintain their lane position, which in turn could reduce attentional resources for other driving tasks.

Key words:

• age‐related macular degeneration
• driver's vision
• low vision

Acknowledgements

We thank Joe Rizzo, MD, Center for Innovative Visual Rehabilitation, Boston Veteran's Administration Hospital, who gave us access to the driving simulator. This research was supported in part by NIH grants EY12890 (Dr Peli), EY018680 (Dr Bowers) and 2P30EY003790.