Question about color vision

Hi all,

I'm not sure if this is the group to ask but I hope that you will point me
in the correct direction if it is not.

Years ago I noticed that while wearing my 2.75 reading glasses I can see the
world clearly but could not focus on the numbers of my blue led alarm clock.
I have no problems with focus on my wife's red led alarm clock.
When I take off my glasses I can see the numbers on my blue led alarm clock
clearly (after a little focus) but can not see the rest of the world
clearly.
I tested my self on some of the online color vision tests and it seems like
I do NOT have any color blindness.
I have used both dime store reading glasses and the high quality ones from
my local eye doctor with expensive coatings with the same issue.
My doctor didn't know what would cause this issue. Time to find a new
doctor?

This is not a major issue to me but I was simply wondering why this is so.
I have some theories but I would like to know if anyone has any real world
explanation as to why this happens.

If it helps, I'm almost 40 and can no longer read small print clearly at
night without a 60-75 watt light bulb (bummer, I remember reading small
print in the dark with no light bulb or glasses) and have a slight
stigmatism.

Thanks,

Chris

"caveat" <caveat-(E-Mail Removed)> wrote in message
newsnBKk.5606$(E-Mail Removed)...
> Hi all,
>
> I'm not sure if this is the group to ask but I hope that you will point me
> in the correct direction if it is not.
>
> Years ago I noticed that while wearing my 2.75 reading glasses I can see
> the world clearly but could not focus on the numbers of my blue led alarm
> clock.
> I have no problems with focus on my wife's red led alarm clock.
> When I take off my glasses I can see the numbers on my blue led alarm
> clock clearly (after a little focus) but can not see the rest of the world
> clearly.
> I tested my self on some of the online color vision tests and it seems
> like I do NOT have any color blindness.
> I have used both dime store reading glasses and the high quality ones from
> my local eye doctor with expensive coatings with the same issue.
> My doctor didn't know what would cause this issue. Time to find a new
> doctor?
>
> This is not a major issue to me but I was simply wondering why this is so.
> I have some theories but I would like to know if anyone has any real world
> explanation as to why this happens.
>
> If it helps, I'm almost 40 and can no longer read small print clearly at
> night without a 60-75 watt light bulb (bummer, I remember reading small
> print in the dark with no light bulb or glasses) and have a slight
> stigmatism.
>
> Thanks,
>
> Chris
>

P.S. I just remembered this, I am nearly blind in one eye (lazy muscle is
what I was told, eye is good but the optic nerve is defective) and can only
make out faint shapes in that eye. If you are born like this then you grow
used to it and don't think about it much.

Chris

In article <DnBKk.5606$(E-Mail Removed)>,
"caveat" <caveat-(E-Mail Removed)> wrote:

> Hi all,
>
> I'm not sure if this is the group to ask but I hope that you will point me
> in the correct direction if it is not.
>
> Years ago I noticed that while wearing my 2.75 reading glasses I can see the
> world clearly but could not focus on the numbers of my blue led alarm clock.
> I have no problems with focus on my wife's red led alarm clock.
> When I take off my glasses I can see the numbers on my blue led alarm clock
> clearly (after a little focus) but can not see the rest of the world
> clearly.
> I tested my self on some of the online color vision tests and it seems like
> I do NOT have any color blindness.
> I have used both dime store reading glasses and the high quality ones from
> my local eye doctor with expensive coatings with the same issue.
> My doctor didn't know what would cause this issue. Time to find a new
> doctor?
>
> This is not a major issue to me but I was simply wondering why this is so.
> I have some theories but I would like to know if anyone has any real world
> explanation as to why this happens.
>
> If it helps, I'm almost 40 and can no longer read small print clearly at
> night without a 60-75 watt light bulb (bummer, I remember reading small
> print in the dark with no light bulb or glasses) and have a slight
> stigmatism.
>
> Thanks,
>
> Chris

I think that you are seeing the effects of chromatic aberration. The
natural eye also has chromatic aberration, but your brain has
accommodated to this by suitable processing of the color receptors
(cones). Wearing glasses introduces new aberration which the brain has
not been trained to process correctly.

Use of this effect was made during the heyday of psychedelics. Posters
in red and blue appeared to not be flat but in relief.

I am not a vision professional. My comments are based upon some
biological knowledge and fairly good understanding of optical physics.
If you think that you do have a physical problem with your eyes, see an
ophthalmologist.

Bill

--
Private Profit; Public Poop! Avoid collateral windfall!

On or about Sun, 19 Oct 2008 00:31:49 -0700 did "caveat"
<caveat-(E-Mail Removed)> dribble thusly:

>Hi all,
>
>I'm not sure if this is the group to ask but I hope that you will point me
>in the correct direction if it is not.
>
>Years ago I noticed that while wearing my 2.75 reading glasses I can see the
>world clearly but could not focus on the numbers of my blue led alarm clock.

It's the correct group, and as you've been told already, it's chromatic
aberration that's at the core of what you're experiencing. In theory, you
could create an incredibly expensive, and incredibly heavy pair of glasses
that minimized the problem by using several different types of lens material
with different levels of dispersion (it'd look like a couple of miniature
telescopes mounted in front of your eyes), but the best you can do in practice
is use an extra-low dispersion material for the one lens.

I don't know off hand what's available for eyeglass use (likely not fluorite,
which would require coatings just to stay intact in the air), but aside from
forcing your OD to look up the best materials for a new pair, the more
practical solution would be to avoid alarm clocks with blue digits.
--
- Mike

Ignore the Python in me to send e-mail.

In article <(E-Mail Removed)>,
Mike Ruskai <(E-Mail Removed)> wrote:

> On or about Sun, 19 Oct 2008 00:31:49 -0700 did "caveat"
> <caveat-(E-Mail Removed)> dribble thusly:

> >Years ago I noticed that while wearing my 2.75 reading glasses I can see the
> >world clearly but could not focus on the numbers of my blue led alarm clock.
>
> It's the correct group, and as you've been told already, it's chromatic
> aberration that's at the core of what you're experiencing. In theory, you
> could create an incredibly expensive, and incredibly heavy pair of glasses
> that minimized the problem by using several different types of lens material
> with different levels of dispersion (it'd look like a couple of miniature
> telescopes mounted in front of your eyes)

I was wondering about this. Camera lenses can be heavy and expensive,
but that's because you want perfect sharpness from edge to edge of the
film, and those lenses that are expensive usually are capable of very
low light use. Camera lenses that are small are really quite cheap.
Since only the macula requires sharpness, I don't see why glasses with
multiple elements would be that expensive and stick out a long ways.
Perhaps I just haven't thought it through or maybe I don't understand
the issues.


> I don't know off hand what's available for eyeglass use (likely not fluorite,
> which would require coatings just to stay intact in the air), but aside from
> forcing your OD to look up the best materials for a new pair, the more
> practical solution would be to avoid alarm clocks with blue digits.

I agree that you have the practical solution for that small problem. I
bought an LED clock with 2" red digits when I couldn't see at night. It
still works well even though I can see OK now.

However, there are a whole lot of blue things in this world, and
sometimes they include numbers and letters, and not always very big.

--
Dan Abel
Petaluma, California USA
(E-Mail Removed)

In article
<dabel-(E-Mail Removed)>,
Dan Abel <(E-Mail Removed)> wrote:

> In article <(E-Mail Removed)>,
> Mike Ruskai <(E-Mail Removed)> wrote:
>
> > On or about Sun, 19 Oct 2008 00:31:49 -0700 did "caveat"
> > <caveat-(E-Mail Removed)> dribble thusly:
>
> > >Years ago I noticed that while wearing my 2.75 reading glasses I can see
> > >the
> > >world clearly but could not focus on the numbers of my blue led alarm
> > >clock.
> >
> > It's the correct group, and as you've been told already, it's chromatic
> > aberration that's at the core of what you're experiencing. In theory, you
> > could create an incredibly expensive, and incredibly heavy pair of glasses
> > that minimized the problem by using several different types of lens
> > material
> > with different levels of dispersion (it'd look like a couple of miniature
> > telescopes mounted in front of your eyes)
>
> I was wondering about this. Camera lenses can be heavy and expensive,
> but that's because you want perfect sharpness from edge to edge of the
> film, and those lenses that are expensive usually are capable of very
> low light use. Camera lenses that are small are really quite cheap.
> Since only the macula requires sharpness, I don't see why glasses with
> multiple elements would be that expensive and stick out a long ways.
> Perhaps I just haven't thought it through or maybe I don't understand
> the issues.

In no way are camera lenses "perfect." The design is always a compromise
among conflicting desires. Optical performance of an eye can be
relatively lax because you turn your eye toward the object being used to
obtain best acuity. Off-axis performance is relatively poor. As you turn
your eye but not your head, you look through a different region of the
spectacle lens. This increases aberration.
>
>
> > I don't know off hand what's available for eyeglass use (likely not
> > fluorite,
> > which would require coatings just to stay intact in the air), but aside
> > from
> > forcing your OD to look up the best materials for a new pair, the more
> > practical solution would be to avoid alarm clocks with blue digits.
>
> I agree that you have the practical solution for that small problem. I
> bought an LED clock with 2" red digits when I couldn't see at night. It
> still works well even though I can see OK now.
>
> However, there are a whole lot of blue things in this world, and
> sometimes they include numbers and letters, and not always very big.

There never was a guarantee that optometry would get you back to where
you were before glasses. In principle, lasik should be able to give you
close to theoretical performance considering the fundamental limitation
of eye anatomy. That performance, however, will be on-axis only. With
glass lenses, the process akin to lasik is called figuring.

I am not a vision or health professional. I know little about the nuts
and bolts of lasik.

Bill

--
Private Profit; Public Poop! Avoid collateral windfall!

Thank you all!!!

I will now set forth upon a great adventure and learn all I can about
chromatic aberration.

This leads to another question, would actual glass be better at minimizing
this characteristic than a poly lens?

Thanks

Chris

In article <P1xLk.5597$(E-Mail Removed)>,
"caveat" <caveat-(E-Mail Removed)> wrote:

> Thank you all!!!
>
> I will now set forth upon a great adventure and learn all I can about
> chromatic aberration.
>
> This leads to another question, would actual glass be better at minimizing
> this characteristic than a poly lens?
>
> Thanks
>
> Chris

Glass comes in a large number of varieties. Look, for example, at the
Schott catalog. Color correction usually uses two different kinds of
glass. That makes color correction for spectacles difficult and
expensive.

Bill

--
Private Profit; Public Poop! Avoid collateral windfall!