I'm not sure why you'd have a problem with opthamologists refering to themselves as doctors, since they're just as much MDs as anybody else who graduated from medical school, unless you're bothered by MDs in general refering to themselves as doctors.
I believe that opthamology is a medical specialty - opthamologists are MDs who have concluded that specialty. Optometrists are not MDs.
My bad - sorry. Although I wasn't really saying I had a problem with it, just a phenomena I noticed.
I was also off base on the European thing, as I remember now that German and Swiss lawyers all like to refer to themselves as Doctors too.
Another curious thing (again, cultural observation) - in the UK, once a medical doctor qualifies as a surgeon, they drop the "Dr" title and revert to being a "Mr" again. Something to do with becoming a Fellow of the Royal College of Surgeons.