Curious about eye movement

[Janey19]

I hope you can solve this for me ...

When you fix your eyes or something - say your own eyes in the mirror - and move your head from side to side, are you eyes actually moving to keep them fixed? Does that make sense. Try as I might, I just can't tell. I can see that my eyes are in different positions in my eye socket, but I'm not sure if it's just my head moving, or my eyes also moving in the opposite direction from my head.

(The reason I ask is that I am trying to tell if I spot I can see is in my eye or outside or it, like an eyelash or something.

Thank you

[Janey19]

Is there anything that would move with the head movement in my example? it kind of moves in synch (same direction) with my head movement and opposite to the eye movement - ie if my eye moves closer to the outside of my eye it gets closer and when my eye is in the inner corner it is further away ....

now I'M confused

[Janey19]

I guess what I mean to say is that when I keep my fixation and move my head, then peripheral spot moves with my head movement, even though my eyes remain fixated. weird

[John C Hagan III, MD, FACS, FAAO]

There are some spots inside the eye that will not move, examples would be a scar or abnormality on the retina, cornea, lens or even the vitreous if very close to the retina. A spot on your eyelashes would move if you open your eyelids as wide as they will go. Something on the surface of the retina outside the eye theoretically would stay in the same place.

JCH MD

[Janey19]

Wow, thank you. Glad I am could explain myself well enough for you to understand what I was talking about (and not think I'm mad)!

SO ... (here I go again) ... if I'm maintaining fixation through this movement, BUT the spot I'm seeing in my eyes is moving back and forth in my peripheral vision, is the source likely inside or outside the eye? (it's NOT a floater)

[John C Hagan III, MD, FACS, FAAO]

Hello Janey19  You may have a great career ahead of you in visual physiology. Yes, when you move your head while maintaining fixation on one object your eyes move in the opposite direction as you head movements. It works in 3 deminsions also. It's a gyroscope like control done by the brain and the inner ear.

Also if you look at an object near or far and close one eye and then the other the object will appear to move this is called parallax and it occurs because the brain is seeing the object from slighlty different views because the eyes are several inches appart.

JCH MD Ophthalmologist