The visual and driving performance of monocular and binocular heavy-duty truck drivers

  • Published: Accident Analysis & Prevention, Volume 23, Issue 4, August 1991
  • Authors: A.J. McKnight, D. Shinar, B. Hilburn
  • Date Added: 30 Jan 2014
  • Last Update: 30 Jan 2014
  • Format: html


  1. To analyse and identify aspects of visual performance that might be affected by monocularity, and the driving functions of truck drivers that are likely to be significantly affected by the reduced visual performance.

  2. To identify and formulate specific measures of visual and driving performance

  3. To compare the visual and driving performance of monocular and binocular truck drivers.


40 monocular and 40 binocular truck drivers with an average age of 44 to 46 years and an average mileage of 58,000 to 61,000 km underwent 8 visual performance tests and driving performance tests on street and off street while being filmed.

Key Findings:

  • The comparison of the visual and driving performance of 40 monocular and 40 binocular truck drivers found that the mononuclear drivers were significantly deficient in contrast sensitivity, visual acuity in low light levels and glare, and binocular depth perception.

  • They were not significantly deficient in static or dynamic visual acuity, visual field of individual eyes, or glare recovery.

  • There was no difference in visual search, lane keeping, clearance judgment, gap judgment, hazard detection, and information recognition between monocular and binocular drivers.However, monocular drives were poorer than binocular drivers in contrast sensitivity, depth perception, minimal illumination for night vision and glare resistance.

  • This meant that the distance at which the monocular drivers could read signs was on average 13% or 5.6 metres shorter in the day than the binocular drivers, and, on average 12 % or 3 metres shorter at night.

  • The total visual field of the monocular drivers (on average 145 degrees) was significantly smaller than that of the binocular drivers (on average 173 degrees).

  • Overall, monocular drivers have some significant reductions in certain visual capabilities in some driving functions that depended on these abilities, compared with binocular drivers. But, they are not significantly worse than binocular drivers in most driving functions.