The New Zealand Land Transport Safety Authority has admitted that
there is no legal definition in this country of a driver who has the
use of only one eye, and has asked me to submit a proposal on the
matter.
I am keen to receive definitions which may be in official use
throughout the world by traffic regulatory authorities, but in
preparing my submission and considering the minimum allowable visual
field for a driver who has lost one eye completely, I need to have
some information as to the degree of head turning that such a person
can be expected to perform whilst driving.
Taking especially the case of a driver who has lost the right eye
totally, and who drives on the left-hand side of the road, or the
driver who has lost the left eye totally and drives on the right-hand
side of the road, but also the reverse situations is the information
is available, with the gaze in the primary position:
1. How far to the right (driving on the left-hand side of the road)
will this driver's head be habitually turned to improve the
perception of objects approaching from the right side? i.e. how much
head turn can be sustained without undue fatigue being imposed on the
left lateral rectus muscle in maintaining the gaze on the road
directly ahead?
2. How much torsional head movement will accompany any head turn, to
reduce the encroachment of the nose into this person's left nasal
field?
3. With the gaze still fixed in the primary position, how far to the
right - with or without a supplementary torsional head movement -
will the same driver's head be turned to any additional degree for
limited periods?
This, or any other related information which net-users are able and
willing to provide to me will be very warmly received.
Denis M Irwin
Optometrist, Auckland, New Zealand