Visual acuity and legal visual requirement to drive a passenger vehicle

Abstract

Objectives (1) To test the consistency and ease with which number-plates of different component figures can be read under DVLA driving test conditions; (2) to test the relative difficulty of reading corresponding figures on registration plates of white and yellow backgrounds. Design Prospective study of consecutive eligible clinic patients. Setting Ophthalmology outpatients. Subjects 210 individuals with a corrected visual acuity with both eyes open of between 6/9 and 6/12. Main outcome measures The ability to read three different number-plates under standard DVLA driving-test conditions (ie at 20.5 m in good daylight with glasses if worn) and the ability to read identical number-plates against a white and a yellow background. Results There is a significant difference between the ease with which three different number-plates can be read depending on their letter and numeral composition, although this did not seem to be significantly affected by whether they were printed on a yellow or white background. Only 92.3% of subjects could read all the number-plates at the legal distance, 96.7% could read at least one number-plate at the legal distance and 3.3% of the test subjects could not read any of the number-plates at 20.5 m. Conclusions The current test protocol used to obtain a driving licence and, moreover, the test the police will employ to assess visual competence to drive, is highly variable and is unlikely to give consistent repeatable results. The performance of those with equally good visual acuity is unpredictable and is highly dependent on the number-plate they are asked to read. This variability could exclude some who would otherwise pass the test or pass an individual with a visual acuity below accepted standards. The forthcoming changes in the regulations for design of number-plates is an ideal opportunity to standardise the whole testing procedure for driving visual acuity.

Tablet App halometer for the assessment of dysphotopsia

“…The effects of dysphotopsia are reported to be most evident during night driving 22 and therefore a level of acuity matching that of the typical driving standard was deemed an appropriate size target for the halometer optotype. 25 The repeatability of the C-Quant was comparable to that previously demonstrated 23 and the Aston Halometer repeatability was shown to be similar. Hence the Aston Halometer appears to provide a sensitive, repeatable way of quantifying a patient recognised form of disability glare in multiple orientations, thus adding a level of objectivity to the subjective reporting of discomfort glare.…”

“…This letter height best approximates the driving standard in many countries. 25 To simulate glare conditions, Bangerter foils were inserted in front of the right eye with the left eye occluded. Bangerter foils contain a series of micro-bubbles, the density of which determines the spread the light.…”

Are Your Eyes “on the Road”? Findings from the 2019 National Study on Vision and Driving Safety in Spain

“…First of all, visual acuity measures, both photopic and mesopic, have been frequently stated as relevant factors to consider for driver' examination [27]. The photopic-high contrast visual acuity indicates the user's visual quality in daylight conditions, and the mesopic visual acuity indicates the vision quality in low light conditions, such as at dusk or when there is fog or rain [28], providing additional insights in regard to functional vision loss processes that may constitute a risk under difficult driving conditions [29].…”

Psychophysical Validation of a Novel Active Learning Approach for Measuring the Visual Acuity Behavioral Function

“…3 For these reasons, the quality of visual acuity assessment is extremely important. Inaccurate and/or imprecise VA assessment could result in unfair classification for paralympic athletes, 4 lost job opportunities, 5,6 or missed diagnoses of real disease and its progression, which may lead to loss of disability benefits 7 or delayed treatment. 8 VA is typically expressed as a single score in logMAR, obtained from testing vision with printed VA charts [9][10][11][12][13][14][15][16] and computerized tests.…”