Outside of an injury, accident, or some chemical ingested or sprayed in the eyes, are there any cases of someone with healthy vision suddenly going blind? I don’t mean gradually, even within a short period of time. I mean good vision one second and BLIP, lights out the next.
I know a guy who lost his sight in one eye, due to a burst blood vessel
- I think he said it was a complication due to diabetes
A friend of mine had a nasty case of the flu when he was 15. Had some sort of a complication from the high fever. Woke up with his optical nerves fried, 5% vision in one eye, nada in the other if I remember correctly.
I’ve gone pretty much blind from optical migraines - but it isn’t “darkness” blind - more like everything is obscured behind swirly, flashing white lights.
What about if somebody had a brain tumor? Couldn’t that do it?
A major retinal detachment would do it, though most likely it’d happen only in one eye at a time. Retinal detachments can occur spontaneously due to changes in the eye with aging. (If you ever get a lot of flashes and/or floaters all of a sudden, possibly accompanied by shadow or a “curtain” over part or all of your vision in that eye, call an ophthalmologist and explain your symptoms!) If you had a bad one, that would qualify.
There’s also a rapid-onset version of glaucoma (acute angle-closure glaucoma) that can cause blindness within a day - dunno if it ever does the “blip” version but it’s fast. I’m not sure if it affects both eyes at once.
The OP specifically rules “ingestion of chemicals”, but still, the one episode I had of (thankfully, short-lived) blindness was caused by drinking a sip of megastrong coffee. No strange substances involved, just your usual caffeine and tannines. Since many people mean “stuff you wouldn’t normally find in food” when they say “chemical”, I figured I’d point this one out.
The world didn’t go black. It went grey.
One morning, six or seven years ago, my Godfather woke up blind. He was blind for several days and then his vision came back. Then, several weeks later, the lights went out again, this time permanently. I can’t remember what the diagnosis is. It has something to do with blood flow.
I know another man from my home town who had the same condition. Fortunately for him, he regained the vision in one eye.
My father is convinced that it has something to do with smoking as they were both long time smokers. The blindness set in within months of them quitting.
The great thing about medicine is that one can always find some oddball circumstance, but on average the answer to your question with its qualifiers is “no,” especially if you are talking about both eyes no longer having their signals get back to the cortex (versus, say, some kind of hysterical reaction or odd brainstem deal that renders the individual unable to process signals that are otherwise mechanically getting through).
You got two eyes. Each has innervation that goes to both sides of the brain. The nerves come together (and half of them cross) at the optic chiasm, and masses can theoretically knock out the chiasm, but suddenly, blip, would be highly unusual. You can flip clots to both retinal arteries, but that’s kind of a long shot. Ditto with bilateral visual cortex lesions. You could fairly suddenly develop conditions which affect both eyes–inflammation of the optic nerve, say–but it’s not blip lights out.
Yes. A long-time friend of my parents went blind pretty much overnight (IIRC, it happened in one or two days) due to a brain condition. It was permanent.
I forgot to mention, if it’s not obvious, that the condition has been permanent.
A girl I went to high school with had a bout of hysterical blindness, which is now apparently called Conversion Disorder. She just woke up one morning and couldn’t see. After a few weeks (and some counselling) her sight came back. There was no physiological cause … it was just stress.
As a young teenager, I once decided to see what would happen if I put a photo strobe right up to my eye and fired it.
Interestingly, I saw in negative for about 2 seconds, then everything went black for a while. Since I was panicking over the anticipated reaction of my parents to this stupidity, it seemed like I was blind in that eye for about a half hour. In reality, it was probably less than 5 minutes.
I had a student several decades ago who woke up blind one morning. Her sight later returned. IIRC, it was an infection of some sort – Bell’s palsy? – that resolved without any specific treatment.
I went to high school with a girl who walked into a door and suddenly went blind. Her vision came back after a few days, but the docs couldn’t figure out what caused it.
Do hairy palms count?
I believe temporal arteritis can cause sudden complete permanent blindness:
I often listen to the Bearman and Keith morning radio show on WZZO in Allentown, PA. It’s mostly comedic.
At one point last year, Bearman suddenly disappeared from the show for a few weeks. I was beginning to think that he had been fired and they just didn’t say anything (as is often the case on radio). Then, fortunately, I happened to be listening on the day he reappeared to explain what was going on and that he’d be gone for a little longer.
It seems that he has long been diabetic, but that he had been failing to take care of it at all, despite symptoms like the skin on his legs suddenly splitting open and leaking water(!). Until one day he woke up completely blind - I believe from blood vessels bursting in his eyes. At the point of him telling this story, he had had surgury to regain partial sight in one eye, and was due to go back in to try to fix the other in the next couple of days. He had come in to tell everyone to take care of themselves properly because it is horrendously frightening to have that happen to you.
He’s been back on the air for several months now, and I have no idea if he has his sight or not. But I’ll never forget that segment - it was extremely affecting. 
Look up amaurosis fugax. That condition covers a lot of the instances described by previous posters.