I think it only happens when I wear sunglasses. The sun creates a small perfectly round bright spot in my vision that looks exactly like what I've seen when looking at hair through a microscope. Not at the highest level of magnification though, more like 40x and not perfectly focused.

When I move my head or blink, the image shifts like when you move the slide under your microscope lens. This glare spot is also not fixed to one region of my vision. It moves depending on the angle of the sun in relation to my eyes.