Homonymous hemianopic field defects and driving in Canada.

Significant functional impairment due to loss of visual field may seriously compromise the safe operation of a motor vehicle. The variable degree of recovery from homonymous hemianopic field defects and the lack of standardized provincial licensing guidelines on visual field defects further compound the difficulty in managing such patients. We reviewed the records of 60 patients with homonymous hemianopic field defects who were followed for an average of 27 months. The ability of the patients to meet the current provincial licensing standards was evaluated on presentation and over the follow-up period. On presentation 34 patients (57%) did not meet the minimum field requirements for an unrestricted license in any province or territory. At the most recent follow-up visit 20 patients (33%) had functional improvement, as measured by their ability to meet the requirements of more regions than they could initially. Four patients (7%) became functionally worse. Patients with homonymous hemianopic field defects should be followed for at least 2 years. The physician should inform the patient that a significant visual disability exists and advise him or her to cease driving when minimum standards are not met.