On 15/03/2013 12:32, djc wrote:
On 15/03/13 08:03, Nightjar wrote:
On 15/03/2013 01:41, Arfa Daily wrote:
....
A very interesting reference document. It is now in my favourites. As to
driving in the dark, I think a lot depends on your age. I don't know if
it is a general physical degradation in your night time vision, or just
a perceived thing. What I do know is that I am a lot less comfortable
now driving in the dark, than I was 20 years ago....

It is age related. I read somewhere that, by the time you are 80, you
have night vision equivalent to a 20 year old wearing dark sunglasses.

Pupil size?
Invest Ophthalmol Vis Sci. 1994 Mar;35(3):1132-7.
Factors affecting light-adapted pupil size in normal human subjects.
Winn B, Whitaker D, Elliott DB, Phillips NJ.
Source

Department of Vision Sciences, Glasgow Caledonian University, United
Kingdom.
Abstract
PURPOSE:

To investigate the effect of age, gender, refractive error, and iris
color on light-adapted pupil size in humans.
METHODS:

Pupil diameters of 91 subjects (age range, 17 to 83 years) with normal,
healthy eyes were measured using an objective infrared-based continuous
recording technique. Five photopic ocular illuminance levels were used
(2.15 to 1050 lumens m-2), and the accommodative status of each subject
was precisely controlled at a constant level.
RESULTS:

Pupil size decreased linearly as a function of age at all illuminance
levels. Even at the highest illuminance level, there was still a
significant effect of age upon pupil size. The rate of change of pupil
diameter with age decreased from 0.043 mm per year at the lowest
illuminance level to 0.015 mm per year at the highest. In addition, the
variability between pupil sizes of subjects of the same age decreased by
a factor of approximately two as luminance was increased over the range
investigated. Pupil size was found to be independent of gender,
refractive error, or iris color (P 0.1).
CONCLUSIONS:

Of the factors investigated, only chronologic age had a significant
effect on the size of the pupil. The phenomenon of senile miosis is
present over a wide range of ocular illuminance levels.

http://www.ncbi.nlm.nih.gov/pubmed/8125724


It might be interesting to read this paper:

http://psychsocgerontology.oxfordjou.../S281.abstract

If only we ordinary mortals could do so. Any gods here with access who
could tell us if it is relevant?

There are several diseases/disorders which affect sight significantly -
but are frequently ignored (e.g. in not being on the DVLA notification
list and not being in what doctors tell patients).

I found this site interesting:

http://www.nhtsa.gov/people/injury/r...s/Foreword.htm

Obviously Section 14 is of particular relevance to this discussion.

--
Rod