Advising patients on visual fitness to drive: implications of revised DVLA regulations.
OBJECTIVE
To examine the relationship between the two UK vision standards for driving: the ability to read a number-plate at 20 m and achieving 6/12 (+0.30 logMAR).


METHODS
120 participants were assessed without refractive correction in this cross-sectional study. Vision was assessed with a Snellen chart, Early Treatment of Diabetic Retinopathy Study (ETDRS) style logMAR letter chart and logMAR chart using Landolt rings. Ability to read a post-2001 number-plate was assessed outdoors.


RESULTS
For all charts, there was an 'overlap zone' of visions within which it was uncertain whether participants would pass the number-plate test. Within this zone, sensitivity and specificity of the 6/12 cut-off for predicting number-plate performance were reasonable for Snellen and ETDRS style charts, but poor for Landolt. All participants with 6/7.5 Snellen (+0.10 logMAR ETDRS) or better could read a number-plate. Some participants (2-6%) with vision between this level and 6/12 could not read a number-plate, and 14%-15% could read a number-plate but not achieve 6/12.


CONCLUSIONS
To best predict drivers' ability to read a number-plate, vision should be assessed using a logMAR letter chart or a Snellen chart scored by full line. Drivers with 6/7.5 (+0.10 logMAR) or better vision can be advised that they meet the driving standard. Drivers with acuity between 6/9 and 6/12 (+0.12-+0.30 logMAR) should be advised to check their ability to read a number-plate, as some may not be able to. Clinicians will see patients who can read a number-plate, but do not achieve 6/12, who will need improved vision to meet visual requirements for driving.
Visual Function and Physiology Research Group, Department of Vision and Hearing Sciences, Anglia Ruskin University, Cambridge, UK Vision and Eye Research Unit, Postgraduate Medical Institute, Anglia Ruskin University, Cambridge, UK.
Keziah
K
Latham
Visual Function and Physiology Research Group, Department of Vision and Hearing Sciences, Anglia Ruskin University, Cambridge, UK.
Maria Foteini
MF
Katsou
Visual Function and Physiology Research Group, Department of Vision and Hearing Sciences, Anglia Ruskin University, Cambridge, UK Vision and Eye Research Unit, Postgraduate Medical Institute, Anglia Ruskin University, Cambridge, UK.
Sheila
S
Rae
D000293:Adolescent; D000328:Adult; D000368:Aged; D001333:Automobile Driver Examination / Q000331:legislation & jurisprudence*; D001334:Automobile Driving / Q000592:standards*; D003430:Cross-Sectional Studies; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D006113:United Kingdom; D014787:Vision Tests / Q000295:instrumentation / Q000592:standards*; D014792:Visual Acuity / Q000502:physiology*
Vision