Experiences of general anaesthetic for eye examination for 4.5 year old

We went to hospital for eye examination with our 4.5 year old but he wouldn't let the Dr check his eyes.  We are going back to clinic in 3 months to see if he will let them then but if he doesn't the only other option GA, we haven't noticed any problems with his vision  and J hates hospitals especially if he had to go to a ward full.of kids as doesn't cope with noise even with defenders.  Just looking for anyone experience of going though this with their kids x