2010 BC Guide in Determining Fitness to Drive

Monocular visionResearch on monocular vision and driving is limited, with most studies conducted before 1980.The evidence suggests that monocular drivers have higher crash and traffic violation rates.Impaired contrast sensitivityIn general, the available research suggests that impairments in contrast sensitivity are associatedwith impairments in driving performance. However, those associations are insufficient tosupport specific decisions regarding loss of contrast sensitivity and continued driving. Moreresearch is required to develop screening tools for contrast sensitivity that are valid and reliablein the driver fitness context.Dark adaptation and glare recoveryDespite its obvious relevance to safe driving performance, there is little in the way of research toassist the medical community or licensing agency personnel in making decisions related to darkadaptation, glare recovery, and driving.Visual field loss including hemianopiaA significant body of literature now exists on the relationship between visual field loss anddriving performance, as measured either by crashes, on-road performance, or from simulatorstudies. Few studies have been done on hemianopia and driving. Taken together, the resultsfrom the on road and crash literature suggest that visual field deficits can and do compromisedriving performance. However, the current body of evidence fails to inform on the extent ofdeficit in the visual field that must be present before driving is impaired.Diplopia and NystagmusThere is little or no research on diplopia or nystagmus and driving performance.CataractsResults on the impact of cataracts on driving performance are mixed, with some studies showingincreased risk of crashes, ranging from 1.3 to 2.5 times higher than those without cataracts.However, other studies have failed to find an association between cataracts and crash rates.Results from studies that have examined self-reported difficulties in driving performance aremore uniform, with the majority of participants reporting difficulties in many aspects of driving.Notably, cataract surgery results in an improvement in visual functioning. However, asignificant percentage of individuals continue to report difficulties in driving, particularly atnight. An important consideration is when driving can safely resume following cataract surgery.Unfortunately, there is a paucity of data to inform on this issue. Of equal importance are theeffects of wait times for cataract surgery on visual functions related to driving. Current literature262