The institution of Part III of NBEO has greatly improved the portability of one's license. In many of the states, Part III is accepted in lieu of the state board's own practical exam. It appears that the only examination that one needs to sit for is the state jurisprudence section.
Few states have reciprocity like in Medicine. Since much of optometry's scope of practice has been achieved through state legislation, reciprocity hasn't gained any sort of hold.
On the other hand, some states have used "licensure by endorsement". States who use endorsement will examine the applicant's state legislation and level of current licensure and if it is equivalent, then the rules are lessened. However, if they are not then there would be much higher testing required.
I'm chagrined by the lack of uniformity of optometry licensing laws, but I don't see any amelioration in the forseeable future.
Richard_Hom