THE MOST important route of sensory input for an automobile driver is the visual apparatus. Fortunately, vision lends itself to quantitative measurements particularly in the vital functions of central acuity and breadth of field. Visual attention, alertness, interpretation, and intelligent decision are also essential in the visual process, but do not lend themselves easily to quantitative measurement. Unfortunately, these functions are subject to wide ranges of variation even under such common conditions as fatigue, anger, or drug reaction.
In the last few years, the previously meager knowledge1 concerning the relationships of medical problems2 and ophthalmic disorders3 to driving has been undergoing distinct improvement. Waller4 in his "Guide for the Identification, Evaluation, and Regulation of Persons with Medical Handicaps to Driving" poses five questions to form the basis for programs to regulate drivers:
What is the accident risk associated with a particular condition?
Visual Factors in Automobile Driving, and Provisional Standards. Arch Ophthalmol. 1969;81(6):865-871. doi:10.1001/archopht.1969.00990010867020