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.