"Round Eye" comes from the Hind Quarter, Cuisse Arriere; it is called in France "Gite a la Noix". Two muscles (cuts) seem to go by that name, an oblique and a vertical one located bellow the "Romsteck" (French spelling).
I believe the Round-Eye is the top part of the vertical muscle. The large muscle muscle of a roast called "Tende de Tranche Roulee" is the Round-Eye!
In Belgium the cuts are called "Filet d'Anvers" and "Grosse Tete". The Filet d'Anvers is used for smoking or air curing like "La Viande des Grisons" in Switzerland.
Bonne Chasse et Bon Appetit!
Tony