The invention involves a surgical ring, designed to be implanted around biological organs comprising a pouch or a duct, so as, on the one hand, to form a
closed loop between these two extremities (1, 2), thus forming a first (1) and a second (2) extremity and, on the other hand, to reduce the
diameter of the opening of said organ when it is tightened by the ring, said ring comprising a
system for reversibly controlling the variation in its
diameter, characterized in that said
system comprises a flexible fillform element (4), inserted longitudinally with possibility of sliding into the material constituting the body of the ring between the first (1) and second (2) extremities, so as to define a fixed portion (5) connected to the first extremity (1) and a free portion (7) associated with an
actuator (8) mounted on the ring near the second extremity (2).