Vision Field Loss Fails to Predict Driver Safety in Patients With Stroke

Homonymous visual field (VF) loss type fails to predict driver safety in patients with stroke, according to research published in Optometry and Vision Science. 

Researchers enrolled 153 participants with withdrawn driver’s licenses due to VF loss from stroke and 83 additional individuals into a control group in an analysis to determine the effects of various VF loss types on simulated driving. VF defects among participants with stroke included homonymous sectoranopia, homonymous hemianopia sparing the macula, quadrantanopia, partial or incongruous homonymous hemianopia, complete homonymous hemianopia, or homonymous scotomatous defects. A group of 93 participants with VF loss resulting from stroke who regained driving privileges following successful completion of the driving simulation were followed for a median 3.8 years for motor vehicle accident involvement. 

Overall, 65% of participants with VF loss passed the simulated driving test (95% CI, 57-72%). Younger participants passed at a higher rate with 70% of participants younger than 70 years achieving a passing score compared with 51% of participants older than 70 years (P <.001). There were no significant differences in reaction time, time headway, collisions, and failure to yield between patients with VF loss and control individuals. 

Participants with homonymous hemianopia with macular sparing had the highest passing rate among individuals with VF impairment, while individuals with scotoma had the lowest passing rate. Right and left-sided VF loss did affect lane position, but did not affect any other measures.

Among participants with VF who had their driving privileges reinstated, 0 were involved in motor collisions during the study duration. 

“In this large cohort, driver safety could not be predicted from the type of homonymous visual field loss,” according to the investigators. “Even individuals with severe visual field loss might be safe drivers. Therefore, it seems reasonable to provide an opportunity for individualized assessments of practical fitness to drive in circumstances of licensing issues.”

Study limitations include failure to enroll sex-matched control individuals, a failure to determine pass and fail rates in control group participants, and a high cost of testing that may have excluded individuals earning a lower income.