Yes, there might be other visual issues that cause problems. Lots of people on the spectrum have problems with flashing lights or particular sights/sounds/textures/smells/tastes. As strange as it might seem, it really helps if someone does exactly what you did - let him explain, help deal with the immediate problem, see if there's any other ways round it in future. I have a fear of wet leaves in case I slip on them, so it's not so much the visual thing, but the fear of ending up in an ungraceful pile on the road.