Iris bombe is due to -
Annular posterior synechiae (ring synechiae) are 360o adhesions of pupillary margin to anterior capsule of lens. These prevent the circulation of aqueous humour from posterior chamber to anterior chamber (seclusio pupillae). Thus, the aqueous collects behind the iris and pushes it anteriorly (leading to 'iris-bombe' formation)
Segmental posterior synechiae
Total posterior synechiae
Ring synechiae
Anterior synechiae
Uveal tract