Poor recognition of the UK minimum driving vision standard by motorists attending optometric practice

Abstract

Purpose: To evaluate the current level of recollection of the vehicle number plate viewing distance in a group of motorists. Knowledge of this distance is required to self-check compliance with the UK legal minimum driving vision standard.

Methods: A cohort of 480 motorists aged > or =17 years attending optometric practice for a routine sight test agreed to participate in a short verbal survey. They were asked whether they could state the current UK statutory vehicle number plate viewing distance as specified in the Highway Code. Also recorded were each motorist's high contrast logMAR visual acuity, whether or not an optical prescription was habitually worn when driving, and brief demographic details (age, gender).

Results: No statistically significant gender-based difference was present in age distribution, mean logMAR binocular acuity, or age and number (proportion) of motorists who habitually wore a refractive correction when driving. The level of mean binocular acuity was uniformly good (<0.0 logMAR, or better than 6/6 Snellen). However, the recollection by respondents of the statutory viewing distance was poor: only 5% were able to state correctly the current distance (20 m), and 22% recalled the previous (20.5 m/67 ft) or the original (22.9 m/75 ft) statutory distance. Of the remainder, 28% underestimated and 45% overestimated the distance. A statistically significant gender-based difference (p = 0.01) between the recollections of non-prescription wearers became marked (p = 0.001) for habitual wearers, in which latter case the median value and range of estimates by female motorists was greater than their male counterparts.

Conclusions: The level of recognition by these motorists of the viewing distance necessary to satisfy the legal minimum vision standard required for driving on UK roads was low and comparable to the levels recorded in two similar surveys undertaken by other authors 10 and 20 years ago. An inexpensive and easily implemented publicity innovation is suggested which could help improve driver appreciation of the statutory distance and promote compliance with the legal vision standard.