"Jaf" wrote in message
...
On Thu, 3 Sep 2009 03:57:02 +0100, "Bill Wright"
wrote:


"james" wrote in message
...
In message , Simon Dean
writes

I like my 100W lightbulb. My eyes strain with anything less,

There's no such thing as eyestrain.

--
James Follett.

Of course there is. It's when your eyes get tired from reading under a dim
light.

Bill

This is rare so savour it, but I'm definitely with James on this one,
There is no such thing as eye-strain.

When I drive on a bright day without dark glasses I get a headache. When my
dad was a medic in Norway during the war a big problem was soldiers
complaining of a feeling of sand in their eyes. This was due to the sun and
the snow. The iris muscles were getting tired. If I read under a dim light I
start to blink and my eyes struggle to focus. This tires the little muscles
that focus the lens, so they protest, and sometimes my eyes water. Sometimes
when I can't find my 'ultra-close-up' glasses I might foolishly attempt to
do a bit of very fine work using my normal bifocals. My eyes are then
struggling to focus closer than they are really capable of, so again the
iris muscles protest. In all these cases the eye is struggling to work under
condiitons that it doesn't like, so it tells the brain that it is unhappy. I
think the expression 'eyestrain' is a suitable one. The eyes are straining
to do something at the limit of their capabilities. I'm not suggesting that
the eyes are damaged in any way by this; just that they tell you that they
are unhappy.

On a related topic, here's a warning. If ever you get a build up of sticky
gunge in the corner of your eye, and possibly a film of it over your pupil,
causing blurred vision, get some antibiotics immediately. I had an eye
infection and delayed treating it for 48 hours, with the result that my left
eye is permanently affected.

Bill