So one of our dogs had a bad case of enthropy on her left eye. We went to the vet, and I asked the vet if I could see the operation from the window (it had curtains). He told me he had a better idea. He shut the curtains, his assistant closed the door, they sterilized me and I saw the operation and he explained to me what he was doing and what it's for! I went through the whole operation without a problem!
Until they were closing the wound. They used an electric plier to burn the cells so the wound would stop bleeding and to kill any possible bacteria. Of course, I had no problem with that. What I did have a problem with was that the electrocal currents were changing her heart's pulse. THAT was what made me lightheaded and almost fell. I left the room right as my knees were giving up and fell on a chair. Never lost consciousness though but I almost did. My sight went fully black but I knew I was conscious because I could still hear properly and move myself. Put my head down and recovered fairly quickly.
So I saw the operation from the moment she fell asleep from the anesthesia to the last step of the operation.