Inter-relationships between British drivers' visual abilities, age and road accident histories.

Statistical analysis is described of data on 1000 British drivers' accident histories and their performance on a vision screening instrument. Significant positive associations are evident between various accident variables and tests of hyperphoria, right eye visual acuity, left eye acuity and binocular acuity. The clustering of associations is strongest for older drivers. The significance of hyperphoria has received little attention previously. The age-related associations with accidents parallel the decline with age of other visual abilities. Statutory re-testing of drivers' vision at about the age of 50 is recommended.