Advising patients on visual fitness to drive: implications of revised DVLA regulations.

Aim 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.
Until