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Registered Member #1334
Joined: Tue Feb 19 2008, 04:37PM
Location: Nr. London, UK
Posts: 615
An experience, certainly. After a lifetime of being told not to look into laser beams, I've just spent two hours with my head locked in a metal & plastic frame doing exactly that. A 532nm Argon laser, as it happens...
Last night I started seeing flashing round the edges of my left eye - an eye I had been warned was damaged after many years of contact sports (rugby & judo mainly) - luckily I knew the warning signs... At first I thought that the flashes were reflections of fireworks (Nov 5th is "Bonfire Night" in the UK) on the inside of my glasses, but soon realised that they continued with my eyes shut - not a good sign... An immediate trip to the nearest emergency eye clinic (speed is essential with this sort of injury), and I was in surgery early this morning for a retinopexy.
Very interesting - 200+ spot welds at an average of just over 200mW / 532nm. Each pulse was like being punched in the eye. At the end, I had a nasty headache, felt a bit nauseous, and due to overload of the photo-receptors, was temporarily blind in my left eye which was anaesthetised with a dilated pupil. A hour or so later, still with evil headache but sight restored, hopefully the retina is now re-attached. Check-up and possibly a few more welds next week...
Registered Member #2261
Joined: Mon Aug 03 2009, 01:19AM
Location: London, UK
Posts: 581
Good luck with that - good job you knew what to do! Am I right in thinking retina detachment is a consequence of banging your head and other large accelerations to the eyes?
Registered Member #1334
Joined: Tue Feb 19 2008, 04:37PM
Location: Nr. London, UK
Posts: 615
IntraWinding wrote ...
Good luck with that - good job you knew what to do! Am I right in thinking retina detachment is a consequence of banging your head and other large accelerations to the eyes?
Partly repeated impacts (which you get in judo or as a second row in Rugby!) and partly a natural propensity due to having a strong astigmatism in that eye - having an astigmatism means your eyeball is oblate, which in turn places the retina under stress. I was warned about 10 years ago something might detach - a routine eye check for glasses - the optician picked up hints that something was not right and referred me to a consultant ophthalmologist... it was the consultant that told me the warning signs... I'm quite glad nothing needed to be done then as the technology is markedly better now...
The pulses were intense - like a brilliant green photographic flash going off in front of your eye 250 times - you can't blink as there is a plastic contact lens holding your eyelids back and the eyeball is anaesthetised - interesting the first few times, then just painful.
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
Nicko, that sucks! Hope the operation was successful. :(
rp181 wrote ...
Myke: Depth perception is primarily from visual cues, Stereopsis has little to do with natural depth perception.
This is one of these things that's "true but not true". My left eye has been weak all my life. My optician tells me that I "Can't see in 3D", but it doesn't matter because depth perception is from visual cues.
Well, that's true when the distance to the thing you're looking at is large compared to the distance between your eyes. This means that the parallax is negligible so there's no "3d information" to be had.
But when I'm peering at some tiny circuit board I find the glasses he made me are a huge help. They have a strong lens in the left eye and practically a plain piece of glass in the right one.
I remember the craze for those "magic eye" stereograms in the 90s. I couldn't see them at all following the normal instructions. If I wore my glasses and crossed my eyes, I could see them, but the depth effect was reversed.
Registered Member #96
Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4061
ouch! thanks for the heads up on the symptoms, useful information.
its interesting to note that people with migraines often experience visual distortions that can mimic this condition, which is why regular eye tests are vital.
Registered Member #3040
Joined: Tue Jul 27 2010, 03:15PM
Location: South of London. UK
Posts: 237
Steve McConner wrote ...
Well, that's true when the distance to the thing you're looking at is large compared to the distance between your eyes.
Yes, it's known that when driving we gauge distance more by the relative size of things rather than by stereo vision. Tests have been done which show that under certain circumstances drivers can mistake a child for an adult standing further away
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Just look into this laser...
