What does rubbing eyes accomplish, physiologically?

It’s SOP for people facing short term eye-stress and such to rub their eyes, and it does work much of the time (at least short term).

What exactly is being done from a physiological standpoint? The only possibilities I can think of are either increasing some sort of fluid, or possibly just a distracting pressure.

The oculocardiac reflex. maybe?

The Oculocardiac reflex , also known as Aschner phenomenon , Aschner reflex , or Aschner–Dagnini reflex , is a decrease in pulse rateassociated with traction applied to extraocular muscles and/or compression of the eyeball.

One might rub for different reasons. It might help remove a foreign body, shift floaters, increase blood flow or reposition a contact lens. It isn’t so effective that people keep rubbing continuously, unless you plan on taking the red eye to Rochester.

You may also be in the beginning stages of “dry eye”.