Vision standards for Driving license in Sri Lanka
With the ever increasing number of vehicles using our roads, it is inevitable that driversneed to call upon increasing use of sensory and motor skills in order to negotiate safelythrough the traffic. Approximately 95% of the sensory input to the brain required for drivingcomes from vision. So it is obviously essential for adequate standards of vision to be set forthe driver of any vehicle and these are set down as either statutory requirements orguidance from the professional body i.e. The College of Ophthalmologists of Sri Lanka
lnitial and renewal applicants are required to take and pass a vision test before
being issued a license.
The "private /personal vehicle" standards should be apptied to:
. Drivers applying for or holding a license for a car, motorcycle, three wheeler or a
light rigid vehicle not used to carry public passengers for hire,
The "commerciat vehicle" standards should be,apptied to:
. Drivers of 'heavy vehicles', (i.e. those holding or applying for a license of classesDE,D,C,DL,C1,CE,J and PT)
. Drivers carrying public passengers for hire (taxi/cab drivers, chauffeurs, drivers ofhiring three wheelers and school vans, etc.)
Vehicle Type Commercialpassenger transportvehicles and all
Heavy vehicles
Light vehicles forpersonal use (not forcommercialpassenger transport)
Three Wheeler forpersonal use (not forcommercial passenger
transport) andMotorcycles
Visual acuity
ln examiningSnellens test type andthe standard nearvision testing shouldbe used.
619r 6/12 or vice versawith or withoutglasses
SlTould wearcorrective Ienses(Spectacles/ contacts)when driving.
The appropriate
correction needs to be
tolerated by the driver.
Uncorrected minimumvision in the worseeye - 6160
6lL2in each eye withor without glasses
Should wearcorrective lenses(Spectacles/ contacts;when driving.
The appropriate
correction needs to be
tolerated by the driver.
6lL2 ln each eye withor without glasses
Should wear correctiveIenses (Spectacles/contacts) when driving.
The appropriate
correction needs to be
tolerated by the driver
Intermediate Vision Absolutecontraindication
Corrected visionBetter eye 6112
Worse eye: 6/18 to6/36
Refer to eye surgeoll- check visual fields -if adequate can allow
Indicate: "Forpersonal use withoutmodifications"
Corrected visionBetter eye 61L2
Worse eye: 6/18 to 6136
Refer to eye surgeon -
check visual flelds - ifadequate can allow.
For three wheelersindicate: o'For
personal use "
Field of visionTest should be
carried out binocularEsterman visual
fields (white target
size Goldnran iii4 e)
140 " in the horizontalrneridianNo defect within 20 "from fixationhorizontally orvertically
140 o in the horizontalmeridianDefbct in one eye
should be completelycompensated by the
other eye
140 o in the horizontalmeridianNo defect within 20 "
fi'om fixationhorizontally orvertically
Monocular vision Absolutecontraindication
(worse eye less than6/12)
Monocular vision(worse eye: 6/60 orless )Under specialcircumstances on an
individual basis couldbe consideredprovided thatfollowing criteria are
met
l.Visual acuity is 6/9or better with orwithout correction.2.Uncorrectedminimum visionshould be 6136
3.Visual fields - 120 "in the horizontalmeridianNo extension ofperipheral defectwithin 20 o fromfixation horizontallyor verticallyWithin central 20'single missed point orcluster of 3 adjoining
Monocular vision(worse eye: 6/60 orless )
Contraindicated as
rnodifications cannot be
done
points is acceptable ifthere are no other field
defects
Indicate: "Forpersonal use withmodifications"
Colour blindness No restriction No restriction No restriction
Diplopia Absolutecontraindication
Assess on an
individual basis.
Diplopia in the
primary position
presents an extretne
hazard to safe driving.Cessation of drivinguntil the diplopia iscorrtrolled rvith
patching or glasses
with prisms. Can
allow as long as
criteria for vision and
visual fields are rnet
after a period of 6months if there is
satisfactory functionaladaptation.
Assess on an individualbasis. Diplopia in the
primary position
presents an extreme
bazard to safe driving.
Cessation of drivingurrrtiI the diplopia iscontrolled with patclring
or glasses with prisrns.
Can allow as long as
criteria for vision and
visual fields are rnet
after a period of 6months if there is
satisfactory functional
adaptatiorr.
Progressivedisorders affecting
vision / visual field orniglit vision
Absolute
contraindication
Can allow as long as
criteria for vision and
visual fields are met.
Review every 2 years
for renewal of the
licerrse.
Can allow as long as
criteria for vision and
visual fields are met.
Consider on an
individual basis renewal
on individual basis -eye surgeon will decide
Nystagmus Absolute
contraindication
Can allow as long as
criteria for vision andvisual fields are met.
Can allow as long as
criteria for vision and
visual fields are met.
Blepharospams Absolutecontraindication
Consider on an
individual basis. Can
allow grade one and
two as long as criteria
Consider on an
individual basis. Can
allow grade one and two
as long as criteria for
3
for vision and visual
fields are met.
vision and visual fields
are met.
Squint Absolutecontraindication fornew applicants
Consider if it is a
renewal of license:
Refer toophthalmologist-criteria for visualacuity and visual
fields should be met.
Some grade of BSVshould be present
Assess on an
individual basis. If an
alternative squint with
adequate visual acuity
and visual fields can
be allowed. Squintr,vith diplopia, consider
criteria for diplopia.
Assess on an individual
basis. If an alternative
squint with adequate
visual acuity and visual
fields can be allowed.
Squint with diplopia,
consider criteria fordiplopia.
Notes on visual fields
The mirrimunr visual field for safe driving is a field of vision of at least l20o on the horizontalrneridian measured by the Goldrnann perimeter on the III4e settings (or equivalent perimetry). Irt
addition there should be notmorethan aclusterof 3 non seeing spots irr the binocularfieldrvhich encroaches withirr the central20o of fixation. By this means, homonymous or bitemporaldefects which come witliin 20o of fixation, whether hernianopic or quadrantanopic, are notaccepted as safe lor driving. Isolated scotomata represented in the binocular field near to thecentral fixation area are also inconsistent with safe driving.
The test must therefore monitor the central area of field as well as its outer perimeter and theintervening meridians. It is obviously essential that the application of the standard should not beeqLripment specific and the phrase "equivalent perimetry" allows the development of equivalentprograms using other perimeters including autoperimeters. Suprathreshold screening tests whichcover the central and peripheral field in each eye are commonly available on most autoperimetersand will satisfy the standard. Central threshold tests, commonly used for routine monitoring ofElaucoma, are helpful in assessing the significance of a scotoma in the central field but inisolation are not r-rseful.
Where the driver has obvious field defects such as a homonymous hemianopia or quadrantanopiathen no confusion arises and the licence is refused. This applies even when the patient has, forrvhatever reason, been driving with this condition for many years. The problem arises, however,when there are equivocal field losses that only just encroach into the permitted field for driving.'[hcse may not rrecessarily be repeatable especially in the elderlywho can have problernsrnastering the perimeter. or in patients with early glaucoma or lightly photocoagulated diabetics.T'o be fair to these patients, it is important to test them on more than one occasion to enable anappropriate decision to be made regarding their driving ability. The Esterman binocular field testallows some enhancement of the binocular field as occurs naturally and also allows fixation bythe dominant eye. Hence it can be seen to be the least stringent test fLrlfilling tlie required
standard. It rnay tlrerefore be used to the benefit of the patient. However, it must be stated that ifthe Esterman test is failed, even by one spot within the 20o limit, it is lil<ely that this represents a
significant scotoma which will lead to the loss of the driving licence. The score given by theprogram is r.veighted to the areas of field important to driving but is of little help in theassessment of the standard. Severe bitemporalherrrianopiawhich extends to the rr-ridline on eitherside can stillgive ahorizontalbinocular field of l20o on an Esterman or other binocular field byrvay of binasal visiorr. It is felt that despite this "full" field, driving is unsafe due to the instabilityof the two lrerniflelds and the inability of the driverto "lock" the fields fi'om the two eyestogether.
Some patients produce very different field test results at different times and it is important tomaximise reliability and reproducibility of the visual field test in all cases. False negative andpositive errors as well as fixation losses must be minirnised to produce accurate results. A fieldslrould be rejected if there are more than20%o of false positive errors. A perintetrist should bepresent with the patient at all times during the test and should carefully explain the test to thepatient prior to beginning. Spectacles, especially fbr a high ametrope, may produce aberrationsand a more accurate test may be produced without them.
Notes on monocular vision
Monocular visiot't is not a cause for disqualification 1'or light vehicles lbr personal use (not forcommercial/hiring passenger transport) providing the visual field in the remaining eye isu,ithin the above definition. This physiological blind spot may be picked up on an Esterman testin a monocular patient and if this is the case, other central visual field tests such as theF{urnphrey 24-2threshold tests should be supplied to demonstrate the otherwise normality of thecentral field.
l-or drivers rvith monocular vision following modifications to the vehicle should be corrsidered.Modified vehicle must present at the time of examination.
l. Disable symbol should be displayed2. Orrly specified motor vehicle3. 2 rear mirrors and 2 front mirrors4. Speed has to be decided by the DMT5. After making modifications to the vehicle need to allow at least 6 months adaptation
tirne fionr the time of loss of vision on one side or as decided bv the consultantophthalmologist.