Vision & Driving

Question 1

Visual Factors

Answer 1

*Visual Acuity
*Visual Fields
*Monocularity
*Eye Movements
*Visual Processing Speed
*Color Vision
*Contrast Sensitivity
*Motion Perception
*Light Sensitivity, glare
*Adaptation
*Age

Question 2

Burg Study

Answer 2

*conclusion: weak correlation between visual
factors and driving performance
*re-evaluated data–weak but significant relationship between accident rates
& DVA & static VA for over 54 years of age, but
NONE under 54 years of age; all others factors
no relationship.
*DVA greater correlation than static VA but no accepted standard for DVA & DVA not repeatable

Question 3

HOFSTETTER STUDY

Answer 3

*Conclusion: individuals with poorer acuity were
twice as likely to have 3 accidents in past 12
months compared with population with better
acuity. Individuals in lower half likely to have 2
accidents in past 12 months
*strong evidence for relationship between driving
performance and visual acuity

Question 4

Results of other studies

Answer 4

• weak but may have significant
  correlation with various parameters
• high contrast visual acuity testing vs. contrast
  sensitivity
  * many tests with driving performance uses high contrast target, may not be good predictor of performance under low contrast lighting situations
• low contrast visual acuity testing may be better: ability to detect pedestrians, seeing edges of roadways, recognizing irregularities in road surface
• contrast sensitivity greater correlation with highway sign discrimination than high contrast visual acuity and perhaps should be
  the method to assess visual performance

Question 5

Is there a relationship between detection and
identification of objects in peripheral field with
driving performance?

Answer 5

many studies–no correlation between VF
measurements & driving performance

Question 6

monocularity

Answer 6

*monocular individuals are at greater risk
for accidents and poor driving behavior
*stereopsis test results not correlated with
accident rates
*CA DMV–automatic failure ? unless
proof of longstanding

Question 7

COLOR VISION

Answer 7

*protanopes (no red) & deuteranopes (no green) expected to confuse red, yellow, green
*green signal standardized to a bluish green, so
dichromats able to distinguish between it and
red and yellow
*protanopes: not proven to have more problem
with red signal, brake or tail lights
*generally, color vision defects not associated
with higher accident rates

Question 8

mature driver

Answer 8

*decreased VA secondary to lens changes, resulting in light scatter
*smaller pupil size
*greater incidence of pathology (maculopathy, retinopathy, glaucoma, cataract)
*other deficits due to age–motor, sensory, cognitive functions
*visual performance
*medical condition
*response time
*medications
*DUI

Question 9

mature driver accidents

Answer 9

*elderly have FEWER accidents, BUT rate of
accident per mile driven is relatively HIGH
*elderly drive less total miles each year
*accidents caused by elderly generally more fatal
*accident rate lowest among 35-54, worse between 18-34

Question 10

overall conclusion

Answer 10

*analysis does not show strong correlation between vision and accidents
*accidents may be due to other factors,
e.g., distraction, sun glare, inattentiveness, cell phone use, obstructed signs, equipment failure, road condition, road rage, etc.

Question 11

VISION STANDARDS

Answer 11

-criteria between seeing and totally blind
-poor relationship between driving performance and visual measures such as visual field, visual acuity
* necessity to set up visual screening standards that are not considered definitive, where failure requires referral for further evaluation & treatment

Question 12

GENERAL DRIVER LICENSE

Answer 12

• most states BVA OU 20/30 to 20/60, 20/40 most common
  -VF 70 to 140 degrees
  -Visual screening failed usually corrected with spectacle, needed for driving
  -screening required for licensure renewal

Question 13

LEGALLY BLIND (per SSA)

Answer 13

*visual acuity - best corrected visual acuity is 20/200 or worse in the best eye
*visual field - the widest diameter of the visual field subtends an angle no greater than 20 degrees in the best eye
*static vs dynamic perimetry
*total visual field efficiency –relates to best eye

Question 14

Visual Field Efficiency

Answer 14

*determine visibility along the 8
meridians (0, 45, 90, 135,180, 225, 270, 315)
*total for each and divide by 5
*greater than 20%

Question 15

CA DMV Vision Standards

Answer 15

*Snellen equivalent: 20/40 OU and 20/40 minimum in one eye and 20/70 minimum in
other eye (Class C vehicles)
*fail 20/40–Optec 1000 device
*target 1 through 6 (1: 20/200; 2: 20/100; 3:
20/67; 4: 20/50; 5: 20/40; 6: 20/33)
*referral failure
*Minimum visual acuity: 20/200 in at least
one eye (otherwise no DL issued)