Hi Terry
>I could have used a beer at the
end of it though ... Can you make a recommendation for this to be
considered as a standard part of the >procedure at your next conference
please Mandy?
A beer afterwards sound good, and maybe one for the
person running the machine too. Imagine how much fun we have watching someone
do the test.
Sometimes we get to see 3 or 4 people do the test in
one day, so that would mean 3 or 4 beers in a day…... I see your
suggestion has some merit J
The automated perimeters, (as we call them), are
actually very sophisticated little machines. They test for threshold. This
means a spot is shown repeatedly at each location to establish the dimmest spot
that can just be seen. It is also able to look for contradictions in your
responses. It will retest in those locations where you have made a
contradiction.
At the end of the test it matches your threshold, with
an aged matched normal, and calculates the difference at each point. This
clearly shows any areas of depressed sensitivity.
With respect to gliding it is not really an indicator
of your peripheral vision. The test is actually only checking the quality of your central visual field, (where
early glaucoma damage is found). The normal test goes out to 24 or 30 degrees.
Whereas the normal visual field extends 50 degrees superiorly,
70 degrees inferiorly, 90 degrees temporally and 60 degrees nasally. So it is theoretically
possible to have a peripheral field loss that would not show up with central
testing.
MT
From:
[EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Terry Neumann
Sent: Thursday, 30 September 2004
4:40 PM
To: Jim Kelly; Discussion of
issues relating to Soaring in Australia.
Subject: Re: [aus-soaring] Best
sunglasses for gliding ?
Jim Kelly wrote:
snip -----------------
And, what was the 'fields test' comprised of Terry?
It was a bit like a game of star wars in some
ways. Mandy may perhaps be amused, or possibly even distraught at
my recollection, but here is the story from the perspective of this
survivor.
The apparatus consists of a large white hemisphere possibly 700mm in
diameter. One eye is covered with a translucent mask and one's head is
placed using a chin rest such that the (other) eye under test looks directly into
this hemisphere at the centre (equator). A yellow light emitting diode is
illuminated at this central point, and one has to focus on it at all times as
the absolute centre of attention. (I didn't know a led could be so boring).
A series of other points of light ( also leds?) then appear very briefly at a
random spot anywhere on the inner surface of this "bowl", one
at a time, and when one is seen, the test pilot has to press a small button
which you hold in you hand. The whole process is driven by a
computer which decides when the point of light will appear and where, and then
records the response of the prisoner thus under duress. I estimate that
it took about ten minutes for each eye but it could have been less - it might
have been more. Time flies when you are having fun. If
you are still breathing and more or less coherent at the end of this, the whole
episode is repeated using the the other eye.
It occurred to me at the time, and more so in retrospect, that this must
present a faintly ridiculous spectacle to anyone who might stumble in on the
scene. I mean, consider if you will, the sight of a somewhat senior
citizen crouched on a chair or stool, complete with high tech pirate
patch, rigid with concentration, his head seeming stuck inside an apparatus
more than a little reminiscent of that seen on the walls of airport
lounge toilets, and stabbing furiously on a button on a device much like a WW 2
bomb release ..... If it happened on the street, the police would
there in a matter of seconds.
At the end of the ordeal the computer plots a nifty diagram as a series of
points where a response occurred. Those points where a light appeared and was
not picked up by the victim show up as areas where a "blind spot" is
present. I had forgotten that we all have a natural blind spot for each
eye - sure enough, I was boringly normal in this respect. There was
one small area of deficiency in the lower left area of the right eye.
This was apparently not a major disaster, and no limitations were suggested, or
action required at this stage.
I should mention that the reason for this test was a slightly elevated pressure
in the right eye during an earlier test. The subsequent field test was, I
understand an additional precaution to check for early signs of glaucoma.
Apparently things were still within acceptable limits, and it will
be monitored more closely at future check-ups.
I suppose after 59 years - nearly 39 of them in gliding, some wear and tear is
to be expected. It occurs to me that perhaps I can sue GFA
for all the hours spent on start and finish lines.... Then there is the
strain of pouring over all of those fuzzy turning point photos in the 70's and
80's.... And I wouldn't be surprised if all that coffee consumed at Exec
meetings as an antidote for the cheap red consumed the night before hasn't
played a part in my downfall. Let me see.... I'll
settle for ... Oh .... say five million - I'll write to the Secretariat as soon
as I post this............
It was an interesting exercise, with potential implications not only for
gliding, but also and perhaps more so for driving where "things out of the
corner of one's eye" can be expected perhaps more often then
in routine flying around the circuit at Balaklava.
I now understand more clearly what the possible limitations
and factors are, not only only for myself, but also for the person in the other
aircraft. Perhaps we should have one in every pie cart as
part of the annual check <grin>.
It was also worthwhile and reassuring. Medicare and/or my health fund
picked up the bill for the game as well - not a bad deal.
I could have used a beer at the end of it though ... Can you make a
recommendation for this to be considered as a standard part of the procedure at
your next conference please Mandy?
Regards,
Terry
