Toric lens manufacture

摘要

A method of cast moulding toric contact lenses is provided in which each lens has a ballast and a toric central zone having a cylindrical axis, the cylindrical axis having an axis of orientation at a desired rotational angle with respect to the axis of the ballast, said method comprising the steps of: (a) providing male and female mould halves wherein the surface of one mould half defines said cylindrical axis and the other defines said ballast axis; (b) loosely assembling the mould halves and transporting the loosely assembled moulds to a filling station under conditions in which the mould halves are free to move relatively to each other in a rotational sense and are subjected to a joggling action during said transport or while being held prior to entry into the filling station; (c) lifting the male mould halves at the filling station, introducing a flowable polymerisable composition into the female mould halves and closing the male mould fully into the female mould halves and curing the polymerisable composition to form toric contact lenses; and (d) sorting the lenses into groups of lenses having the same or similar rotational angle.