Your symptoms sound like mine when I had ocular migraines. It would start as a pinprick in the front of my vision that I could not see, then it became a squiggly line and I would lose all my peripheral vision. They last about 1/2 hour. It's hard not to panic when in the middle of them. Sometimes I would get headaches after, sometimes not. If you google "ocular migraine," you can read about them. I would always get them a couple days after I'd been under a lot of stress. Thankfully, I haven't had one in about 5 years.