KONTAKTLINS OCH FORFARANDE FOR FRAMSTELLNING AV DENNA

摘要

With a high minus powered anterior surface toric lens with a prism ballast there is a difficulty in maintaining stability of the lens. In this invention a contact lens particularly a high minus powered anterior surface toric lens is made having a toric central optical portion (1) without prism and an annular outer portion (3) having prism but without toric effect, the outer portion being truncated in a lower part (5) so that there is upward movement of the centre of rotation (9) of the blank and of the centre of gravity (8) in a manner such that the centre of gravity is in use below the centre of rotation, thus assisting if the lens is rotated by lid or eye movement the lens tends to rotate back into correct orientation.