The brain does an awful lot with blurry and outright missing data. Look at something in your peripheral vision and name the colour of it, that's the brain filing in information that your eyes can't see. We only have good eyesight in a surprisingly small region directly in front of us.
> The dividing line between near and mid peripheral vision at 30° radius is based on several features of visual performance. Visual acuity declines by about 50% every 2.5° from the center up to 30°, at which point visual acuity declines more steeply.[18] Color perception is strong at 20° but weak at 40°.[19] 30° is thus taken as the dividing line between adequate and poor color perception. In dark-adapted vision, light sensitivity corresponds to rod density, which peaks just at 18°. From 18° towards the center, rod density declines rapidly. From 18° away from the center, rod density declines more gradually, in a curve with distinct inflection points resulting in two humps. The outer edge of the second hump is at about 30°, and corresponds to the outer edge of good night vision. - https://en.wikipedia.org/wiki/Peripheral_vision
So the weird thing is that both my eyes have a visual acuity around 20/120 or worse; that’s with correction (glasses) and it depends on the day (tiredness/dryness/etc) — but having lived this way my entire life essentially, I find it REALLY difficult to describe what it’s like to people. People think things off in the distance must be ‘blurry’, but that’s not the case at all. It’s more like ‘less detailed’, like if you turn the resolution and texture detail down. It’s not like an unfocused lens at all. There are studies I’ve found that seem to back this up.
Another problem I have that’s related is a nystagmus - both my eyes oscillate involuntarily from side-to-side, separate from the normal saccades (rapid eye movements) that everyone has. You’d think I’d see the whole world oscillating from side to side - but I don’t at all. I don’t usually even notice these movements when I look in the mirror, though I can see them if I’m looking at a video of my own face.
That is, most of the time. There’s one really strange failure mode I’ve observed - PWM-controlled small LED lights or segment displays like on a digital clock, particularly if they’re red but green as well, in a dark room. If it’s dim enough that I can still dimly see what surrounds the display, I can sometimes notice the LED oscillating left and right, WHILE THE STUFF SURROUNDING IT STAYS STILL. It’s really freaking weird!
in short: the eye and brain are complicated!
If I look at the car's rear trunk lid and hold my eyes still for a few seconds, the raised brake light starts moving up! (Or down, I don't remember which direction right now, but I think it's always the same direction.)
And it's not like everything in my vision is moving with it, that one raised light is moving all by itself. And it keeps moving and moving in the same direction, but somehow stays in the same place.
It's a strange experience, almost like a Shepard Tone of vision.
That went away over time, even as my prescription became much more nearsighted (I'm almost 9 diopters now)
I've tried to learn how to do this myself with very limited success. If I try to force my eyes to become blurry and then unblurry, I can notice some improvement in my ability to resolve images underwater. But this probably takes a lot of practice, and my lens is already starting to harden with age.