Tatia, the SFEMG tests the activity of muscle fibers. There are no muscles in the eyelid itself, right? So there would be no reason to insert the needle into the eyelid itself (thank goodness).

Half an hour seems about right to me, from my three EMGs.

Abby

I had an EMG. It was not bad on the legs and arms. It did hurt a lot on the face. In my case, it didn't reveal anything. As far as I can tell, it was a waste of time and pain. It might be very valuable for some people.

There are muscles in the eyelid. I know for certain, the pretarsal portion of the orbicularis oculi goes right up to the eyelashes. For ten years, I got Botox injections directly into the eyelids to treat muscle spasms. There are definitely muscles in the eyelids, and needles into the eyelids is not as big a deal as it sounds.

I'm not certain, but I think the levator palpebrae superioris muscle is also in the eyelid, because when administering Botox injections for blepharospasm, the center of the eyelid must be avoided because of the levator muscle. When that muscle becomes weakened by Botox, the result is ptosis.

So if the EMG equipment never touched my eyelids, is it possible my levator is affected, but wouldn't have shown up on the EMG? Is it a different muscle than the levator that causes ptosis in myasthenia gravis?

Yes, they test the orbicularis occuli, which is responsible for closing the eyes not keep them open. The assumption is that if the levator is effected the orbicularis occuli will also be effected.
The other assumption is that if you have occular myasthenia, your SFEMG (testing your eye muscles) may be normal, but if you have generalized myasthenia it has to be abnormal.

I have to admit that I never understood the logic behind those assumptions, but guess I am not smart enough. At some point I just stopped trying.

I suspect that the assumptions are wrong.
I also suspect that you are smart.

I had it on the face. It was very uncomfortable, and the length of the procedure is probably what makes it so bad, rather than actual shocks. I wouldn't say its painful, per se, though. I'd check with the doctor before taking something as you don't want to screw up the test and have to go through it again.