v for frequency?

There are legions of people who need things to keep them occupied, lest they make trouble for the productive people.

What do they use the sulphur hexafluoride for?

It's a dense gas which, when breathed, reduces the resonant frequency of the vocal cavities. Kind of the opposite to helium. I've often thought that, if breathed by a prepubescent boy, he could sing like a castrato without any surgery needed. "Viva la morte col coltello!"

The vitreous fluid is removed from the eye during the procedure. The gas is used to inflate the eye and hold the retina in position while the vitreous fluid regenerates.

It gets a bit strange during that phase. The image on the retina is upside down like in a camera; the brain inverts it. So, as the fluid replaces the gas it's filling in from the bottom but what you see is a band of vision on top of what looks like one of those photos taken with a camera partially underwater. It's hard to explain.

Veal, preferably.

Years ago I would get lamb kidneys, split them, and broil them for breakfast. I haven't seen them in a market in ages. If I did they'd probably be costly. I briefly looked at a shank in leg of lamb Sunday but the $110 price cost me my appetite and I opted for beef liver.

It was very weird, totally blurred initially and then like looking through the porthole of a sinking ship. It took me about two months for the final bubbles to go away.

The refill fluid is liquid, no collagen, so it won't tear bits off your retina like the original rigid gel can. My floaters are gone now, too.

I think the collagen is part of an oxygen diffusion barrier between the retina and the lens. The retina is the most oxygenated part of your body and the lens doesn't like a lot of oxygen.

My doctor used disulfur hexafluoride. Previously he used to use freon.

Did you experience "floaters" prior to the retinal damage? That's supposed to be a symptom; I had floaters in one eye a few months ago but they've mostly gone away now. I see an ophthalmologist once a year in any case as I might develop glaucoma one day.

A fair proportion of it isn't the brain so much as the second level behind the retina. That is where all the processing that sees edges and fast moving threats in peripheral vision take place. It means you can react to an incoming threat like an insect flying into your eye and blink before there would have been time for a round trip.

In that case you have to have the prescription made for a particular working distance or it will be miles off for close up work.

Here it is a standard car number plate at 20m - not much of a challenge. (UK number plates the numbers are quite large 79mm 3.1" high)

The brain corrects the signals from two eyes. I can look around without glasses, and then put them on. Or just look around at odd angles. In both cases, the two images have different magnifications or different distortions. Imagine tracking a fly buzzing around your head, for example. Your brain does multiple focal length and distortion corrections in real time. Two-eye resolution is markedly better than one. I think there is dithering and a lot of DSP going on.

The image on your retina surely has gross geometric distortion, but a good machinist can spot a not-straight line to a fraction of a degree.

After my last eye surgery, my eyes wouldn't coordinate. One image was horribly twisted and zoomed and offset from the other. I could barely walk. I thought I was doomed. After about a week, things suddenly snapped into perfect alignment. My brain adjusted.

I elected to be nearsighted, so I don't use glasses for reading or computing or close work. I'm an engineer, not a hunter-gatherer.

I use my Mantis for really close work, and a Mantis is not very compatible with glasses.

I'm better off not correcting my astigmatism. I've thrown away two or three pairs of expensive glasses learning that.

I've always had floaters. After two vitrectomies, they are mostly gone, and the big Lego-like structures are all gone.

After I had the last vitrectomy, I had a lot of tiny floaters, little round dots and, I swear, tadpole swimmers. Repair crew? They are gone now.

It's been interesting.

I remember an experiment where the subject wore inverting lenses. After a few days his brain adapted. I think George Stratton was the first experimental psychologist to try it.

Experimental psychology is quite a bit different to the pap in 'Psychology Today'. The Frankfurt School and its descendants have no use for it in their Critical Theory since it depends on sound scientific technique and not woo-woo.

Yes. They're pretty common and I have one in my left eye that sometimes masquerades as a mosquito. The onset in my right eye was much more dramatic due to the blood diffusing in the fluid. It took a few days for it to settle down to the point where the doctor could see the retina well enough to do the laser welding.

It's only when you swat at them...

I've imagined two separate 3D images somehow scattered around inside two gooey masses of brain cells. The two jello bags are in effect constantly distorted to adjust for each eye's inherent geometry and distance and lens fl and viewing angles. And then they are cross-correlated to merge the images to a 3D moving picture with higher resolution than either had alone. With both eyes constantly jerking around. For moving objects. In milliseconds. With chemical logic elements.

How can people hit baseballs? Or read?

Before my first big repair, I had a tear that dumped a bit of blood into my humor. It looked like thousands of black dots swirling around. (That retima soon detatched.)

The optics of seeing blood cells, or floaters, is strange. They must be very close to the retina to cast a sharp shadow. Even a mm away their image on the retina must be a blur. And just above our retina object resolution must be microns or better.

Some floaters are amazingly complex and sharply imaged.

I watched my last retina repair, local anasthetic only. I could see the shadows of all the tools, the green-dye injector and the tweezers and other gadgets. The doctor and his nurse gave me a running explanation and I could ask question when nothing critical was going on.

Magic. I'm not a creationist by any means, but there are questions I prefer not to ponder, starting with Heidegger's 'why is there something rather than nothing?' People have been chewing on that since Parmenides.

I had a chance to try such goggles once. It was seriously disorienting and very hard after you put them on and almost as hard when you took them off again at the end of a session. Also an experiment trying to sign your name on paper where you were looking at it through a periscope thing that flipped the directions that your hand moved.

I recall banks in the UK once had silly anti forgery pens with a wide skirt that were almost impossible to hold comfortably and prevented you from seeing the point of contact with the paper. Must have been someone's acid trip brainwave. The result was that nobodies signature looked anything like correct or in the right place on the form. ASCII art doesn't quite convey how ugly they were

___| |___ \__ __/ | | \ / ' It was quickly abandoned. Anyone in the UK remember them? Did it happen in the US too?

It is more like we keep an updated model of the world around us in some sort of 3D memory network and are forever looking for threats or things to eat. Our eyes and brain evolved to handle an ancient world of eat or be eaten where food had to be found or caught before you could eat it.

We can be quite easily fooled by well aimed misdirection. Most close up magic tricks rely on misdirection and the brain filling in any gaps with plausible "data". The internal world model we have is remarkably good.

In many ways a fly's eye and brain processing power touse it is even more impressive. Imagine having to sort out the mish mash of convolved overlapping images that come from a compound eye lens into stereo vision.

Dragon flies are truly impressive top insect predators and have been so for a *very* long time.

We can learn some remarkable skills given practice. Basic pattern matching is one of the things that boot straps written languages. Some people struggle with mirror writing and either end up dyslexic or able to read text in any orientation on a desk (bad news for their managers).

The ability to anticipate and plan for what someone else is about to do is half the battle in returning a fast serve or saving a penalty. It is an application of the skill that once allowed us to catch live prey.

It would be quite handy to be able to dodge bullets - particularly in the USA.

Why not?

If there were nothing, who would ask the question? It is what it is.

Given that existence exists, and reasonably sane implementations of Darwinism, stuff that kills you doesn't last, stuff that is merely pointless, like male nipples and appendices, hangs round to generate amusement and stuff that helps you stay alive, like binocular vision prospers.

End of.

You should be able to dodge sniper bullets if you see the flash and duck. Flight time is a bit transonic so say 1200mph, so a 1 mile shot takes 3 seconds to hit.

In fact most people with a hand gun cant hit a stationary target at 6 feet. So moving fast is a very good option

There is a gimmick I saw at at local fair. The challenge is to ride a bicycle 50'. There is a gear train in the head that reverses the handlebar direction. The shill makes it look easy but few make it more than a few feet.