Jamieson, Fausset and Brown on Isaiah 52:8

8. watchmen--set on towers separated by intervals to give the earliest notice of the approach of any messenger with tidings (compare Is 21:6-8). The Hebrew is more forcible than English Version, "The voice of thy watchmen" (exclamatory as in So 2:8). "They lift up their voice! together they sing."

eye to eye--that is, close at hand, and so clearly [Gesenius]; Nu 14:14, "face to face"; Nu 12:8, "mouth to mouth." Compare 1Co 13:12; Re 22:4, of which Simeon's sight of the Saviour was a prefiguration (Lu 2:30). The watchmen, spiritually, are ministers and others who pray for the peace of Jerusalem (Is 62:6, 7),

bring again--that is, restore. Or else, "return to" [Maurer].