Cast mould for manufacturing contact lenses or intraocular lenses

An injection mould for forming a cast mould, comprising:

• a first injection mould half;
• a second injection mould half;
• and
• at least one injection mould cavity formed between the first injection mould half and second injection mould half, the at least one injection mould cavity comprising the following connected cavities:
• a central part cavity centered on a longitudinal central axis (A);
• a bearing ring cavity radially outward of the central part cavity;
• and
• a connecting cavity fluidly connecting the central part cavity to the bearing ring cavity, wherein an axial height of the connecting cavity is less than 0.1 times an axial height of the central part cavity at the longitudinal central axis (A);
• a plunger in the first injection mould half, the plunger movable along the longitudinal central axis (A), the plunger having an end face facing the at least one injection mould cavity and forming a boundary of the central part cavity;
• and
• a spring urging the plunger toward the second injection mould half, wherein
• the cast mould is formed by injecting a flowable material into the entire injection mould cavity.