Having your vision checked by a doctor regularly. The aging process also can decrease peripheral vision which may affect driving performance. Also, be aware that older drivers' eyes need more light to see well but also, are more sensitive to glare. Getting plenty of rest during planting, harvesting, and longer working periods. Take breaks to protect yourself against fatigue and physical stress.
Accidents are more likely to occur when fatigued and stressed.
Drinking plenty of fluids. Understanding the medication your taking and its effect on reaction time. Making sure a family member or neighbor knows where you will be working. Knowing and understanding your limitations. Don't push your body and mind past its health and safety limits.