[John Chapman (OP)]

After being out in the Sun and coming inside, if I shut my eyes really hard I can see spots.

Can you still see them when your eyes are open? Try looking at something white, like a sheet of paper. What about the colour change?

[Chemistry4me]

Well you see, at the moment there is no Sun or Moon for that matter (because it is pouring) []
I'll try again later today, if the Sun decides to come out []

[John Chapman (OP)]

I thought it was always sunny in New Zealand. Let me know how you get on. I await your results with baited breath.  []

[Chemistry4me]

Well I tried it with the bathroom lights while brushing my teeth, but unfortunately, still no colours, just a faint black spot for a couple of seconds (and a headache!) []

[Chemistry4me]

The headache is worse than I expected! This is just friggin great! []

[Chemistry4me]

I think I've been looking at the screen for too long. In addition with the light experiments, my well-being is even worse!

[Karen W.]

when i come from otside in the sun...My field of vision goe totally black....you know the song..."Blinded by the light" takes two to three minutes to adjust plus a huge heaache...

never seen colored spots..but white floaters when the blood pressure is two high....

Hope your head stops hurting right away....
you need a defuser screen on your monitor they help.....

Sorry for your headache...

[John Chapman (OP)]

Oh no. You're not going to sue me for damages, are you? I do like to see someone prepared to suffer for their science.

I've decided that in the absence of anyone confirming that I'm not a freak I'm just going to have to pluck my eyes out. If anybody reading this has experienced my freakish visual anomaly for themselves please speak up quickly as it will only take a few minutes for me to find a teaspoon!

In the meantime, sorry Chem4me about the headache!  []

[Chemistry4me]

In the meantime, sorry Chem4me about the headache!  []

No worries [] Plenty more clone eyeballs to spare experiments coming up!

[Chemistry4me]

Okay so one of my useless clones I went outside and had a look around, then I came back in and looked at a white wall... NOTHING! Not literally, just nothing colourful []

[Chemistry4me]

Still NOTHING!

[John Chapman (OP)]

Ha ha. I think I'm definitely a freak.

I'll just have to wait and see if anyone else reading this thread has experienced the same. When I started it I assumed that everyone would instantly know what I was talking about. Thanks for getting all the Chem4mes having a go.

[Chemistry4me]

The weird thing is, I think I'm a freak as well (but a different kind)!
This morning, I did a 100m sprint and afterwards my vision was blurred and everything was really bright.

BEFORE.

 [ Invalid Attachment ]

AFTER


 [ Invalid Attachment ]

IT was freaking me out!!  [] [] [] []

[Chemistry4me]

WHAT'S GOING ON?

[John Chapman (OP)]

Hi Chem

That would worry me. Are you a fit person? Has this happened before?

I would be tempted to check that out with my GP. Be careful. []

[Christopher1]

What blot you are looking at...



newbielink:http://www.southcoastrecovery.com/ [nonactive]

[John Chapman (OP)]

Hi Christopher1.

Welcome to the site.

I am trying to establish whether other people experience colour changing blotches floating in their vision after looking at a bright light. The original question was:

Can anybody tell me why, after a bright light is shone into your eyes, you then see a dark purple blotch floating in front of your vision?

Also, if you blink or close your eyes at this stage the blob will instantly turn bright green while your eyes are closed and back to purple once they are open again. Why is that?

It seems that generally people experience the 'light blotch' but no-one here knows what I am talking about when I say it changes colour when I close my eyes. What do you think?

[yor_on]

John if I remember right it is the fluid or rather gel we have inside our eyes that make that effect. The reason we notice it is that the rods and cones that react to light sits on the 'bottom' of our eyes, so light have to traverse the full length of the eye before getting 'registered' by the brain. That gel have small 'impurities' in it that we don't notice normally, but can see at times.

And colour is just the way your brain might interpret a light stimuli. Or was it the Iris? Anyway, if you close your eyes and press on them with your fingers you will be able to see both shapes and colours, not because there is light coming to them, just because that pressure you are applying on your eyes will be interpreted by the brain as having both shape and colour.

"The rods are more numerous, some 120 million, and are more sensitive than the cones. However, they are not sensitive to color. The 6 to 7 million cones provide the eye's color sensitivity and they are much more concentrated in the central yellow spot known as the macula."
http://www.kellogg.umich.edu/patientcare/conditions/anatomy.html

[yor_on]

Mr Chem, as you run your blood pressure goes up, as your heart and lungs works 'overtime' to keep you oxygenated. In fact, your body behaves much the same as when under threat.

"When under stress your body prepares to deal with the situation. Several hormones are secreted from your adrenal glands to allow your heart rate to speed up, to constrict the blood vessels to your gut and to enlarge the blood vessels to your muscles, to dilate your eyes so you can see better. 

Those hormones stimulate your liver to release glucose for quick energy. Fat deposits are induced to liberate free fatty acids for fuel. 
our body does this so you are in a heightened state to deal with the event that is causing your stress. "

Mr Chem?
Does this mean that you see glades as a threat to our security?

[techmind]

Can anybody tell me why, after a bright light is shone into your eyes, you then see a dark purple blotch floating in front of your vision for several minutes?

Also, if you blink or close your eyes at this stage the blob will instantly turn bright green while your eyes are closed and back to purple once they are open again. Why is that?

The bright light momentarily bleaches the photo-receptors in the retina of the eye. The effect is typically noticed for up to a few minutes for 'common' bright lights, but may last longer if the light is seriously/dangerously bright.

The after-image colour you see is often substantially complementary to the colour of the bright light, so a bright red light might tend to create a cyan after-image, and a blue light might make a predominantly yellow after-image - if you're looking at a white surface. It does depend what colour (and brightness) surface you're looking at.

If you see the after-image when looking at a white surface then you are effectively subtracting a portion of the colour from the previous exposure... but if you shut/cover your eye so no 'new' light is entering, but still see an after-image then clearly there must be a different effect at work.


Having just done some empirical study [], I notice that the coloured splodge I see with my eyes open (against a bright surface) is slightly dark, while if I close my eye I see a bright burn-in on a dark backgroud (mysteriously my brain makes it come and go).

Having used a bluey-LED cycle lamp, I'm seeing a yellowy blob against the white on my computer-screen, but a magenta-y blob against the cream-coloured wall. When I close my eye and make it dark, I see a cyan coloured blob. But the colours change as the burn-in weakens.

I reckon that as well as the physcial bleaching, the brain plays tricks to conceal the physical artifact (which partly explains why the blob comes and goes), and this may also cause the colour to change.


Another thing you may observe is that if you've been laying in the sun for a few minutes with your eyes shut (you'll see the bright red of the blood in the eyelinds), when you open your eyes and look around everything will look bluey-green (and completely lacking in red) for a few minutes until the red-receptors have recovered.  [8D]