It must be scary for you to hear that about yourself and hopefully I can give you a possible answer that will put your mind at ease about it.
You *might* have
pendular nystagmus. Any eye doctor should be able to tell you if you have it. I have had it since I was born. What I have is harmless and I sometimes pass it off as a party trick. Most people don't even realize I have it unless something triggers it when I'm talking to them. I have been affectionately called Googly Eyes because of it. Here's an example I found of the movement:
Pendular Nystagmus
Most people have these eye movements to some extent when their eyes are trying to focus, but for people who have the disorder the movements are more exaggerated. The cause is either the muscles in each of your eyes pulling in opposite directions or a neurological anomaly. For me, it happens when I am trying to focus on an object from a certain angle. It also happens when my emotions change suddenly - suddenly angry, happy or stressed. They tend to do it when I'm tired and in certain lighting. The "party trick" I do is if I spin around in circle and then stop, my eyes will move back and forth really fast. It freaks some people out and some people are just entertained by seeing me spin around. When they are moving quickly, it does cause my vision to temporarily blur for a couple seconds while my eyes are trying to regain focus.
Most doctors and people do not know about the disorder. I freaked out a medical intern once because my eyes were doing it and she thought it was from vertigo or something crazy. She didn't ask me why my eyes were moving because she probably didn't want to scare me. When the doctor came in and started shining a light in my eye and asking me to watch his finger as she moved it back and forth, I realized what was happening and told them about my eye disorder.
If you want to test out if you have it, you could try spinning around and then record your eyes with the video function of your phone to see if they are doing it. Since I assume you are an adult, I'd be surprised if you had the congenital (born with it it) disorder that I have because someone would have likely pointed it out much sooner. I did a quick google search and it is possible for PN to be acquired. I never knew that could be the case. I would definitely go to an eye doctor and get it checked out. I've found that normal doctors are clueless about it. There is a possibility that it could cause an issue for you if it gets worse but the eye doctor should be able to give you some answers.
It would be interesting to find out if PTSD can cause someone to develop the disorder. Please keep us posted on what you find out. Good luck and welcome to the club (possibly)!
Just to add to what I stated above, the eye movements were a consideration for doing EMDR because I have to move my eyes a certain way. The one EMDR person I went to had me hold these things called "tappers" in my hands that were vibrate at alternating times instead of having me do side to side eye movements.
