If I take 3 playing cards and arrange them in front of my eye, so that
a very small triangular aperture is created by the cards, and I adjust
this aperture so that it is sufficiently small for the brightness of
the light to be somewhat diminished, I notice I am able to observe the
droplets of fluid on the surface of my eye (especially when I blink)
which I ordinarily can't see. What am I doing to the light, and why
can I see the fluid? Thank you.

If I take 3 playing cards and arrange them in front of my eye, so that
a very small triangular aperture is created by the cards, and I adjust
this aperture so that it is sufficiently small for the brightness of
the light to be somewhat diminished, I notice I am able to observe the
droplets of fluid on the surface of my eye (especially when I blink)
which I ordinarily can't see. What am I doing to the light, and why
can I see the fluid? Thank you.

If I take 3 playing cards and arrange them in front of my eye, so that
a very small triangular aperture is created by the cards, and I adjust
this aperture so that it is sufficiently small for the brightness of
the light to be somewhat diminished, I notice I am able to observe the
droplets of fluid on the surface of my eye (especially when I blink)
which I ordinarily can't see. What am I doing to the light, and why
can I see the fluid? Thank you.

On Jul 9, 2:15 am, daniwe... at (no spam) gmail.com wrote:
If I take 3 playing cards and arrange them in front of my eye, so that
a very small triangular aperture is created by the cards, and I adjust
this aperture so that it is sufficiently small for the brightness of
the light to be somewhat diminished, I notice I am able to observe the
droplets of fluid on the surface of my eye (especially when I blink)
which I ordinarily can't see. What am I doing to the light, and why
can I see the fluid? Thank you.

My guess is that you're diminishing the ambient light enough that only
the area very close to the surface of your eye is illuminated. You've
filtered out the light from all of the other things you normally look
at so as to make this possible.

On Jul 8, 11:15pm, daniwe... at (no spam) gmail.com wrote:

If I take 3 playing cards and arrange them in front of my eye, so that
a very small triangular aperture is created by the cards, and I adjust
this aperture so that it is sufficiently small for the brightness of
the light to be somewhat diminished, I notice I am able to observe the
droplets of fluid on the surface of my eye (especially when I blink)
which I ordinarily can't see. What am I doing to the light, and why
can I see the fluid? Thank you.

I used to think of the exact same question. I have bad eyes so I just
needed to take off my glasses and look at a point light source to see
interference pattern from the liquid drops on the eye. Blinking the
eye lid kind of refreshed the surface.

It was a question from me about the whole meaning to interference as
related to the objective study of cause to the pattern. I would try
to distinguish the interference between two such liquid drops
patterns. A light to dark overlay occurs when two patterns resolve.

I was simply curious. And in the end a common interference pattern
was all I could attribute to this event. Objective eye effect as a
mysterious event of the eye was found to NOT exist. A patttern self
effect proved the common event of interference. A source of light and
the eye as the sensor was all it means. No mysterious eye effect is
seen.

On Jul 8, 11:15=A0pm, daniwe... at (no spam) gmail.com wrote:

If I take 3 playing cards and arrange them in front of my eye, so that
a very small triangular aperture is created by the cards, and I adjust
this aperture so that it is sufficiently small for the brightness of
the light to be somewhat diminished, I notice I am able to observe the
droplets of fluid on the surface of my eye (especially when I blink)
which I ordinarily can't see. What am I doing to the light, and why
can I see the fluid? Thank you.

I used to think of the exact same question. I have bad eyes so I just
needed to take off my glasses and look at a point light source to see
interference pattern from the liquid drops on the eye. Blinking the
eye lid kind of refreshed the surface.

It was a question from me about the whole meaning to interference as
related to the objective study of cause to the pattern. I would try
to distinguish the interference between two such liquid drops
patterns. A light to dark overlay occurs when two patterns resolve.

I was simply curious. And in the end a common interference pattern
was all I could attribute to this event. Objective eye effect as a
mysterious event of the eye was found to NOT exist. A patttern self
effect proved the common event of interference. A source of light and
the eye as the sensor was all it means. No mysterious eye effect is
seen.

... I notice I am able to observe the
droplets of fluid on the surface of my eye (especially when I blink)
which I ordinarily can't see. What am I doing to the light, and why
can I see the fluid? Thank you.

On Jul 8, 11:15 pm, daniwe... at (no spam) gmail.com wrote:

... I notice I am able to observe the
droplets of fluid on the surface of my eye (especially when I blink)
which I ordinarily can't see. What am I doing to the light, and why
can I see the fluid? Thank you.

You are assuming this is fluid on the surface of your eye:  It can't
be, because the absorbance of anything in corneal fluids (barring
some sort of disease) is too low.   What you are seeing is dead blood
cells
and other detritus in the vitreous humor, casting shadows right
against
your retina.   The analogy to a pinhole camera is correct:  The small
hole
allows the point-spread function to be very narrow, allowing high-
resolution
vision of this stuff.

You also may be able to see strands of broken fibers which used to
anchor the
vitreous humor to the eyeball.   As you age, your vitreous humor turns
slowly
from firm jelly to watery liquid, starting near the retina.   It
fragments and
detaches from the retina.  So, the stuff you see will become more
heavily
populated ("dirtier") as you age.   This won't interfere with vision,
because it
in not in the retinal object plane.   But, refractive index
differences in the vitreous
humor may make your vision intermittently blurry as you age; this
resembles
the effect of mucous or other substances in the tears but is not.

On Jul 13, 5:42�pm, "jw... at (no spam) BasicISP.net" <jw... at (no spam) basicisp.net> wrote:
On Jul 8, 11:15�pm, daniwe... at (no spam) gmail.com wrote:

... I notice I am able to observe the
droplets of fluid on the surface of my eye (especially when I blink)
which I ordinarily can't see. What am I doing to the light, and why
can I see the fluid? Thank you.

You are assuming this is fluid on the surface of your eye: �It can't
be, because the absorbance of anything in corneal fluids (barring
some sort of disease) is too low. � What you are seeing is dead blood
cells
and other detritus in the vitreous humor, casting shadows right
against
your retina. � The analogy to a pinhole camera is correct: �The small
hole
allows the point-spread function to be very narrow, allowing high-
resolution
vision of this stuff.

You also may be able to see strands of broken fibers which used to
anchor the
vitreous humor to the eyeball. � As you age, your vitreous humor turns
slowly
from firm jelly to watery liquid, starting near the retina. � It
fragments and
detaches from the retina. �So, the stuff you see will become more
heavily
populated ("dirtier") as you age. � This won't interfere with vision,
because it
in not in the retinal object plane. � But, refractive index
differences in the vitreous
humor may make your vision intermittently blurry as you age; this
resembles
the effect of mucous or other substances in the tears but is not.

Thanks to everyone for your thoughtful replies!

I believe I am certainly seeing droplets of fluid on the surface of my
eye for the following reasons:

1. Blinking permanently changes their number, size, shape and
position.

2. If I squint, I am able to "corral" them together.

When my head is positioned vertically, relative to the ground, the
droplets seem to drift chiefly downward (and slightly sideways at
times) after I blink. When I position my head sideways, the droplets
seem to describe a curved path after I blink, initially fast toward my
lower eyelid, and then slower, curving away towards the ground. At no
time do they seem to drift up, away from the ground. I think their
movement is being influenced both by gravity and by surface tension
and/or other fluid mechanical behaviors, which, however, I have no
technical knowledge of. But it seems clear these are tear droplets,
rather than floaters, which, being inside the eye, would not be so
influenced and modified by blinking.

- Dan

Hi.

You can't tell tears from floaters by anything you so far have
described, because the eye moves when you blink, and you
don't know whether the objects you see are more or less dense
than the fluid supporting them. I have seen floaters, and I
can't tell them from something on my cornea by any simple
experiment.

However, you can do a direct test of the tear hypothesis by
taking a piece of transparent plastic (Saran wrap) or some other
thin, transparent sheet, making a tiny
cut or other mark on it, wetting one side with saline solution (in
case you accidnetally touch your eye), and
putting it very near your cornea while you do the card trick.
You could suspend your film on a
spectacle frame, for example. Put the cards beyond the film.
If you see the mark you made, then it is POSSIBLE
you might be seeing something on your cornea.

Also, if you can see stuff in your tears with the cards, you
should be able to see the same stuff by looking in a good mirror with
a magnifying glass and a bright light. If there are blood cells,
specks of
solid mucous, pigmented protozoa, or anything else highly absorbant
in your tear film, you should visit an ophthalmologist, because this
would be an indication of a possible injury or disease condition.

Keep in mind that a pinhole light source has no magnification, so
something 2 cm from your retina (viz., on your cornea) would
have to be quite big, a mm or so, for you to see the silhouette image
of it.
On the other hand, something right against your retina would
be so close that it would span several retinal photoreceptors and
thus have a pinhole image with easily visible detail.

Touching a little on the physics of this problem, an inverse distance
law for resolution of detail holds for an object illuminated by a
pinhole
light source, just as it holds for any other source.

daniwe... at (no spam) gmail.com wrote:
On Jul 13, 5:42=EF=BF=BDpm, "jw... at (no spam) BasicISP.net" <jw... at (no spam) basicisp.net> w=
rote:
On Jul 8, 11:15=EF=BF=BDpm, daniwe... at (no spam) gmail.com wrote:

... I notice I am able to observe the
droplets of fluid on the surface of my eye (especially when I blink=
)
which I ordinarily can't see. What am I doing to the light, and why
can I see the fluid? Thank you.

You are assuming this is fluid on the surface of your eye: =EF=BF=BDI=
t can't
be, because the absorbance of anything in corneal fluids (barring
some sort of disease) is too low. =EF=BF=BD What you are seeing is de=
ad blood
cells
and other detritus in the vitreous humor, casting shadows right
against
your retina. =EF=BF=BD The analogy to a pinhole camera is correct: =
=EF=BF=BDThe small
hole
allows the point-spread function to be very narrow, allowing high-
resolution
vision of this stuff.

You also may be able to see strands of broken fibers which used to
anchor the
vitreous humor to the eyeball. =EF=BF=BD As you age, your vitreous hu=
mor turns
slowly
from firm jelly to watery liquid, starting near the retina. =EF=BF=BD=
It
fragments and
detaches from the retina. =EF=BF=BDSo, the stuff you see will become =
more
heavily
populated ("dirtier") as you age. =EF=BF=BD This won't interfere with=
vision,
because it
in not in the retinal object plane. =EF=BF=BD But, refractive index
differences in the vitreous
humor may make your vision intermittently blurry as you age; this
resembles
the effect of mucous or other substances in the tears but is not.

Thanks to everyone for your thoughtful replies!

I believe I am certainly seeing droplets of fluid on the surface of my
eye for the following reasons:

1. Blinking permanently changes their number, size, shape and
position.

2. If I squint, I am able to "corral" them together.

When my head is positioned vertically, relative to the ground, the
droplets seem to drift chiefly downward (and slightly sideways at
times) after I blink. When I position my head sideways, the droplets
seem to describe a curved path after I blink, initially fast toward my
lower eyelid, and then slower, curving away towards the ground. At no
time do they seem to drift up, away from the ground. I think their
movement is being influenced both by gravity and by surface tension
and/or other fluid mechanical behaviors, which, however, I have no
technical knowledge of. But it seems clear these are tear droplets,
rather than floaters, which, being inside the eye, would not be so
influenced and modified by blinking.

- Dan