Its an interesting question

I expect you can tell the eye is not quite right if you were to know
him better.  Many people for example dont notice George Bushes eyes.
These kinds of eye deviations are quite commonly observed but most
people are unware of seeing them or having them.

Apparently (I just learnt) Glass/Acrylic eyes are adjusted to be
looking straight ahead in a natural manner at 3 feet for Americans and
18" for Europeans because Americans prefer more personal space.

There seem to be two mechanisms controlling eye movement.

1. Is that eye movements are in some manner connected together via
crossover of the optic nerves and accommodation or focus.

But

2. What you are actually looking at seems able to over rule the effect
of 1.  this can be demonstrated because you see a picture best when the
two images are precisely and accurately overlaid. (various none
accurate overlays are possible where binocular vision is apparent but
it can never be as good as an accurate overlay because the correct
information is unavailable to the brain)

For example if you get two identical pictures its possible with
practice to place them on the floor, stand up tall and move these
pictures to various distances and still merge them together as a single
picture.  (I tried this for stereoscopic pairs but with the greater
distance it is not noticably 3D)

Alternatively if you get two identical coins you can merge them into a
single coin at the near point in a variety of positions including some
where the eyes are pointing outwards from being parallel - this starts
to feel seriously weird though because the eyes are physically looking
majorly away from the coins, while your attention  attempts to keep the
pictures together.

Supposedly some people have learnt to do that without the pictures
looking straight ahead but i have never personally seen it.  It sounds
possible though.

Finally just to add some additional complexity, in behavioural
optometry its commonly known that when stressed our eyes do not
accurately point at the same object, but outside of behavioural
optometry this is often regarded as being impossible even though
strabismic and temporarily exo/esotropic eyes can be observed and
phorias are easily revealed.

Andrew

I can't speak for hers, I didn't know she had one, but my prosthetic
eye isn't glass, it's some kind of plastic material.  My right eye was
removed, and replaced with a hydroxy-apetite (sp?) ball, with the eye
muscles then sewn around it.  After that healed, this clay-like stuff
was injected into my eye socket to get an impression, then when that
was shaped and hardened they painted it to match my other eye.  This
"eye" which kind of looks like a half clamshell, then just fits in
front of the ocular implant; it's a perfect fit, so when the eye
muscles move the ocular implant, the prosthesis moves with it.

From what I have seen, true "glass" eyes do not move or look like the
real thing.  I'm betting Sandy Duncan has the same type I do.

It depends on the structure under her blind eye, if she has part of the
blind eye remaining or if the entire eye has been removed, and the type
of prosthesis she wears.  Many prosthetic eyes (not made of glass) move
in accordance to the seeing eye.  My son's prosthesis (scleral
shell--kind of like a large, thick contact lens) has some movement and
you'd really have to pay attention to know which eye is real and which
is not.

This is a good website that explains it all.  It's the site that I
read in depth when I was having my plastic implant replaced with a
hypoxyapatite (coral) one.

http://www.ioi.com/

Ann

I know this is an old thread but I am new and just saw it.......Sandy Duncan
DOES NOT have a glass eye. In the early 70's she was treated for a tumor
behind her eye. This left her blind in that eye but the muscles still track
with the other eye. This is just a rumor that was started. Though I DID see
an interesting segment on "How They Make It" on the science channel and they
gave a great segment on the making of a prosthetic eye.