>>40530820>he was seeing those shadow men in the corner of his eyes here and thereYour peripheral vision is distinctly different than your center of vision. For example your peripheral vision can't see color almost at all and is particularly good at sensing movement. When you're sick to the point that your eyes aren't working well your center of vision gets worse, but the relatively more simple features of your peripheral vision stay mostly intact. This can feel like you're peripheral vision is, paradoxically, better than normal when your eyes are strained or not working perfectly because you're so sick.
Shadowy figures in the corners of your eyes is common because of this. An important part is the loss of color vision at the periphery of your vision. Many colors perceived as "bright" or easy to see like a lot of red, blue and green things are actually very dark without color. Like a bright red apple will look like a dark grey blob in monochrome. This is where the shadowy figures actually come from, objects that look normal turn very dark when they enter your peripheral vision.
This all happens with normally working eyes as well, but you've learned to tune it out (your brain basically paints on top of what you're actually seeing with your peripheral vision based on what it remembers an object looking like when you last saw them with your center of vision) since it's been like that forever. When your eyes change however, then the shadowy figures might appear. Add on top of that being in an unfamiliar place and it can make you really jumpy.
Personally, I've only had it once when I took a test in college while horribly hungover and hungry. My eyes were really strained and whenever I'd try to focus on the test, I'd see a dark clothed figure standing next to me, which made me stand up multiple times to give them enough space to move past me. There was never anybody anywhere close to me.