A cushion assembly for a patient interface including an elastomeric seal-forming structure that is shaped to be bisected by a sagittal plane having a line that is tangent to the elastomeric seal-forming structure at a superior tangent point and at an inferior tangent point. A saddle-shaped superior region of the elastomeric seal-forming structure straddles the sagittal plane and includes the superior tangent point. The elastomeric seal-forming structure transitions in a cylinder-shaped superior region from the saddle-shaped region to a dome-shaped superior region offset from the sagittal plane. In addition, an elastomeric wall thickness of the elastomeric seal-forming structure is greater in the cylinder-shaped superior region than in the saddle-shaped superior region and the dome-shaped superior region.