Those who support age-based testing point to the statistical evidence that shows that older people, especially age 85 and above, are responsible for accidents at a much higher rate than their younger cohorts, and are more likely to be involved in a second crash. There is no denying that age-related deficits are common in older people but it is important to keep in mind that no two people age alike. There is variation in degree, time of onset and pattern. The day a 65-year old gets his or her first social security check does not mark the beginning of a sudden and dramatic decrement in all areas. Nevertheless, there are several factors that could contribute to a reduction in driving skills.
Vision changes are common in many older adults.
Focusing ability decreases, and the pupils let in half as much light as in younger days. Passing another car can be riskier when depth perception weakens, making it harder to judge the distance and speed of oncoming traffic. Add to these a potential for greater sensitivity to glare, reduced vision at night, and a decrease in side vision and it's not hard to recognize a formula for reduced efficiency in the key driving skills. Serious medical conditions such as macular degeneration, glaucoma and cataracts also take their toll. And some elders wait too long before having surgery to remove cataracts.