Sharon; I've had both eyes done. The first time the local optician tried to check my eye pressures my body nearly fainted (although my conscious mind was telling me not to be silly). My mum was a nurse, and I have memories of her explaining that sometimes you could pop an eyeball out to check if there was anything at the back causing irritation. That memory stayed deep in me, hence the fainting feeling when the optician approached my eye with his harmless gadget.
When in later life I had to be checked out and was eventually operated on, I saw it as something I had to cope with as a grown-up; something that was really happening and that I would have to make the most of it.
The actual operation on my first eye was completely painless and I coped with it by relaxed breathing and breath-counting and with the help of a beautiful honey-skinned nurse who held my hand throughout in case I needed to give her a squeeze to let her know that I was still alive and needed to communicate.
I didn't feel a thing and was fascinated to see what was happening (albeit without a lens, so out of focus for a while).
The second eye was a while later and was just the same.
I imagine it sounds scary, but I am a huge coward and I managed to get through it without any pain or panic.
Try not to be afraid. It's not as bad as it sounds.
Best wishes.