Naked Science Forum

Life Sciences => Physiology & Medicine => Topic started by: Simulated on 05/12/2007 18:35:23

Title: Why can't I see anything?!
Post by: Simulated on 05/12/2007 18:35:23: OK I lied I can still see, but I just came in from outside with all the snow and the cold and my eyes are like not letting me see anything? Why is that?
Title: Why can't I see anything?!
Post by: stana on 05/12/2007 18:41:14: Your eyes have got used to the whiteness and the glare of th snow, and when you come inside its much darker? hence your unable to see for a short while. The same thing happens when you have a light on in your bedroom. You turn off the light annd get into bed, after a short while you will be able to see things you couldnt of seen when you first switched the light off!
Title: Why can't I see anything?!
Post by: Simulated on 05/12/2007 19:03:20: Ah that's what I was thinking. So If i ate a bunch of carrots it wouldn't make it so extreme? lol.
Title: Why can't I see anything?!
Post by: techmind on 05/12/2007 23:16:13: Quote from: Simulated on 05/12/2007 18:35:23
OK I lied I can still see, but I just came in from outside with all the snow and the cold and my eyes are like not letting me see anything? Why is that?

Two things happen:
- firstly the pupil of your eye closes in bright light (like the iris/aperture control on a camera) and takes a while to open up again when you go somewhere dark
- secondly the photo-receptors in the retina can become saturated and bleached by all that bright white light, and take a while to recover normal sensitivity.

Think of a nice warm summer day; you lay out in the sun on your back and close your eyes. To start with you see a strong red through your eyelids, but over a minute or so the red becomes slightly weaker. Now open your eyes and look around and the whole garden looks bluey-green because the red-receptors in your eye got temporarily desensitised by all that red light when your eyes were closed and the sun shone on your eyelids.
Title: Why can't I see anything?!
Post by: Simulated on 06/12/2007 01:59:43: AH well how come if I just lay there and rub my eyes for aw hile and just squint really hard and sometiems not even squint it um has this yellow circle type thing?
Title: Why can't I see anything?!
Post by: stana on 06/12/2007 16:26:29: thats because your damaging the nerve endings and stuff in your eyes, I used to push my fingers into my eyes, and i seen like..a visualisation like on game consoles! I can still do it, and once i let go, the visison just slowly fades from my eyes.
Title: Why can't I see anything?!
Post by: Simulated on 06/12/2007 23:22:09: Ah I see! Sometimes it looks like oh what the best thing to describe it. Um windows media player vizulations on random!