Were you in Europe? Did you have an E1.11 as it used to be called...if so then you can claim it back by contacting Department of Social Welfare. Or do you have Private Health Insurance you might be able to claim it there. Failing that, I think you can claim it back as Med1 type claim but it might have to be EU...someone would need to clarify...
As far as I am aware when that qualifying health care is only available outside Ireland you can - this being the case I presume when you traveled specifically for that health care, see post above for other cases.
Why not give Revenue a call, that are a helpful bunch.
I have just read the Rev Commissions Leaflet on claiming medical expenses (IT6) and it does not specify that the medical expenses must have been incured in Ireland.
The point about the health care only being available outside Ireland is only mentioned
in relation to travel expenses, not the medical expenses.
I did a search on this site, and Clubman says that he successfully claimed for expenses incured abroad.