49 ms·

That's interesting, because when working with UV light I could feel pain in my eyes, so the body does have some sort of defense mechanism.

by jules 10y ago

throwanem 10y ago
That's not really a defense per se, just a warning that something is wrong. I had pain in my left eye when I burned my retina with a laser, too, but that didn't reduce the damage.
- deleted 10y ago
  [deleted]
- jules 10y ago
  Warning signals do reduce damage though: if you hadn't gotten the warning then maybe you would have continued burning your eye. I certainly would have continued looking at the UV light if I hadn't felt any pain.
  - throwanem 10y ago
    It was a visible-wavelength laser, so I would've known there was a problem as soon as it hit my retina, even without the audible click and the sudden and disquietingly misplaced feeling of having been kicked pretty hard in the nuts. But I take your meaning. (And I own a pair of wavelength-matched laser goggles now, as should you if you're going to do anything at all with a laser and any kind of focusing optics. Carelessly enough handled, even a 5mW pointer beam can pose a real risk. Don't make the same mistake I did!)
    - a_t48 10y ago
      Laser to the eye causes testicle pain?
      - xorxornop 10y ago
        Probably "overwhelming" pain. Where you almost complete loss of rationality, a torrent of sensation that blocks out all other thought and sensation - vision narrows to a point, sound becomes choppy and discordant, limbs feel far away or even absent (no, I don't mean the one that's potentially chopped off or something ;) , the other ones)
        throwanem 10y ago
        Oh, it wasn't anywhere near that threshold! (Although it was well over that for swearing the air blue.) See my sibling comment to yours; I just meant that the nature of the sensation was almost identical to that produced by a shot to the area, just in my head instead of my belly - and, yes, that really does feel as weird as it sounds like it would.
        deleted 10y ago
        [deleted]
      - throwanem 10y ago
        Oddly enough, yes! Not in the same area, obviously. But if you recall the last time you caught a blow to the business, then imagine how that'd feel in your head instead of your belly, that'll give you a decent idea of what it was like. I don't know what else would, short of actually replicating the injury; I've had enough shiners to know what that's like, and while it's not at all pleasant, I'd probably choose it over another laser burn if I weren't given the option of declining both. Fascinating though it was, I have to say I found the experience with very little to recommend it, not least because it disquiets to realize that the click you've just heard, conducted through the bone and tissue of your head, was produced by a small volume of fluid inside your eyeball suddenly boiling.
        jacobush 10y ago
        Beautiful language.
      - 10y ago
- jacobush 10y ago
  Don't look into laser with remaining eye.
- owenversteeg 10y ago
  If you don't mind me asking, what was the damage, and what wavelength/power was it? Laser eye incidents fascinate me since there's not too much information about them. [edit] My email's in my profile if you'd prefer not to say publicly, although since a few others upvoted my comment it looks like it's a popular question :)
  - throwanem 10y ago
    I don't mind at all! Happy to oblige. It was a 405nm (violet) 5mW diode laser, housed in a pointer of a sort that's sold cheaply on eBay [1]. It was focused through a spherical lens taken from an old scanner and another from a broken magnifying glass. With such a short focal length, it should've been very hard to injure myself, but I had my head quite close to the bench and was also messing with a couple of mirrors. Given such a golden opportunity, Murphy rarely fails to oblige, and in this case he obliged me right in the eye. (The idea there, if you're curious, was to build a light collector with a relatively wide incidence angle that'd focus the beam onto a mostly decapsulated violet LED reverse-biased to act as a photodiode and tied to the base of an NPN transistor, so as to switch a GPIO on my entertainment center Raspberry Pi and use the laser pointer as a kind of remote control. The circuit worked quite well when illuminated, but a ~1mm target is hard to hit from ten feet away, hence the messing about with focusing optics.) I don't have a detailed characterization of the injury because I'm rather overdue for an optometrist's appointment, but later experiments with the same configuration (and goggles!) showed that, so focused, the beam would deform and start to burn black ABS plastic within a few seconds, and took no perceptible time to burn a hole in a sheet of black construction paper, in both cases producing damage in a radius well under a millimeter - I found that, unless placed precisely in the focal plane, the beam was too widely spread even to raise smoke from the paper. The effect on my retina would therefore have had to be the same sort of closely localized heating, a hypothesis borne out by the effects I observed to result. Beyond the pain already described (which lasted a good couple of hours), those effects included the click sound I mentioned, which I believe to have been produced by the sudden vaporization of a small volume of aqueous humor adjacent to the retina, and a quite noticeable but thankfully non-foveal bright green floater which did not cease to be perceptible until about a month had gone by. Whether this latter is the result of the injury healing, as I gather such minor retinal injuries often do, or rather of my visual cortex having grown a new filter, I won't know until my next slit-lamp exam. [1] http://m.ebay.com/itm/Teaching-Powerful-405NM-Blue-N3ioiet-Purple-Laser-Pointer-Pen-5MW-Light-Beam-DD/252706512339 http://m.ebay.com/itm/Teaching-Powerful-405NM-Blue-N3ioiet-P...
hvidgaard 10y ago
Our eyes are extremely advanced. When I stand near a laser cutter, of course wearing protection glasses, I can feel it in my eyes whenever it is turned on.
nommm-nommm 10y ago
I always found this interesting... I have worn polycarbonate lenses my whole life, well since infancy. Polycarbonate lenses block UV light. If I go outside without my glasses or sunglasses my eyes hurt, even in winter. I don't know if my eyes are super sensitive or they just aren't used to the UV light and the micro-damage it causes.
- pitaj 10y ago
  Do you have blue eyes?

That's interesting, because when working with UV light I could feel pain in my eyes, so the body does have some sort of defense mechanism.

by jules 10y ago

That's interesting, because when working with UV light I could feel pain in my eyes, so the body does have some sort of defense mechanism.

throwanem 10y ago

That's not really a defense per se, just a warning that something is wrong. I had pain in my left eye when I burned my retina with a laser, too, but that didn't reduce the damage.

deleted 10y ago
[deleted]
jules 10y ago
Warning signals do reduce damage though: if you hadn't gotten the warning then maybe you would have continued burning your eye. I certainly would have continued looking at the UV light if I hadn't felt any pain.
- throwanem 10y ago
  It was a visible-wavelength laser, so I would've known there was a problem as soon as it hit my retina, even without the audible click and the sudden and disquietingly misplaced feeling of having been kicked pretty hard in the nuts. But I take your meaning. (And I own a pair of wavelength-matched laser goggles now, as should you if you're going to do anything at all with a laser and any kind of focusing optics. Carelessly enough handled, even a 5mW pointer beam can pose a real risk. Don't make the same mistake I did!)
  - a_t48 10y ago
    Laser to the eye causes testicle pain?
    - xorxornop 10y ago
      Probably "overwhelming" pain. Where you almost complete loss of rationality, a torrent of sensation that blocks out all other thought and sensation - vision narrows to a point, sound becomes choppy and discordant, limbs feel far away or even absent (no, I don't mean the one that's potentially chopped off or something ;) , the other ones)
      - throwanem 10y ago
        Oh, it wasn't anywhere near that threshold! (Although it was well over that for swearing the air blue.) See my sibling comment to yours; I just meant that the nature of the sensation was almost identical to that produced by a shot to the area, just in my head instead of my belly - and, yes, that really does feel as weird as it sounds like it would.
        deleted 10y ago
        [deleted]
    - throwanem 10y ago
      Oddly enough, yes! Not in the same area, obviously. But if you recall the last time you caught a blow to the business, then imagine how that'd feel in your head instead of your belly, that'll give you a decent idea of what it was like. I don't know what else would, short of actually replicating the injury; I've had enough shiners to know what that's like, and while it's not at all pleasant, I'd probably choose it over another laser burn if I weren't given the option of declining both. Fascinating though it was, I have to say I found the experience with very little to recommend it, not least because it disquiets to realize that the click you've just heard, conducted through the bone and tissue of your head, was produced by a small volume of fluid inside your eyeball suddenly boiling.
      - jacobush 10y ago
        Beautiful language.
    - 10y ago
jacobush 10y ago
Don't look into laser with remaining eye.
owenversteeg 10y ago
If you don't mind me asking, what was the damage, and what wavelength/power was it? Laser eye incidents fascinate me since there's not too much information about them. [edit] My email's in my profile if you'd prefer not to say publicly, although since a few others upvoted my comment it looks like it's a popular question :)
- throwanem 10y ago
  I don't mind at all! Happy to oblige. It was a 405nm (violet) 5mW diode laser, housed in a pointer of a sort that's sold cheaply on eBay [1]. It was focused through a spherical lens taken from an old scanner and another from a broken magnifying glass. With such a short focal length, it should've been very hard to injure myself, but I had my head quite close to the bench and was also messing with a couple of mirrors. Given such a golden opportunity, Murphy rarely fails to oblige, and in this case he obliged me right in the eye. (The idea there, if you're curious, was to build a light collector with a relatively wide incidence angle that'd focus the beam onto a mostly decapsulated violet LED reverse-biased to act as a photodiode and tied to the base of an NPN transistor, so as to switch a GPIO on my entertainment center Raspberry Pi and use the laser pointer as a kind of remote control. The circuit worked quite well when illuminated, but a ~1mm target is hard to hit from ten feet away, hence the messing about with focusing optics.) I don't have a detailed characterization of the injury because I'm rather overdue for an optometrist's appointment, but later experiments with the same configuration (and goggles!) showed that, so focused, the beam would deform and start to burn black ABS plastic within a few seconds, and took no perceptible time to burn a hole in a sheet of black construction paper, in both cases producing damage in a radius well under a millimeter - I found that, unless placed precisely in the focal plane, the beam was too widely spread even to raise smoke from the paper. The effect on my retina would therefore have had to be the same sort of closely localized heating, a hypothesis borne out by the effects I observed to result. Beyond the pain already described (which lasted a good couple of hours), those effects included the click sound I mentioned, which I believe to have been produced by the sudden vaporization of a small volume of aqueous humor adjacent to the retina, and a quite noticeable but thankfully non-foveal bright green floater which did not cease to be perceptible until about a month had gone by. Whether this latter is the result of the injury healing, as I gather such minor retinal injuries often do, or rather of my visual cortex having grown a new filter, I won't know until my next slit-lamp exam. [1] http://m.ebay.com/itm/Teaching-Powerful-405NM-Blue-N3ioiet-Purple-Laser-Pointer-Pen-5MW-Light-Beam-DD/252706512339 http://m.ebay.com/itm/Teaching-Powerful-405NM-Blue-N3ioiet-P...

hvidgaard 10y ago

Our eyes are extremely advanced. When I stand near a laser cutter, of course wearing protection glasses, I can feel it in my eyes whenever it is turned on.

nommm-nommm 10y ago

I always found this interesting... I have worn polycarbonate lenses my whole life, well since infancy. Polycarbonate lenses block UV light. If I go outside without my glasses or sunglasses my eyes hurt, even in winter. I don't know if my eyes are super sensitive or they just aren't used to the UV light and the micro-damage it causes.

pitaj 10y ago
Do you have blue eyes?