The moulding tool is a near-net-shape negative mould for shaping a ceramic green body for the lens. The mould has a shaping surface, which is described by the following equation B: y ⁢ ⁢ 1 = cz 2 1 + 1 - ( k + 1 ) ⁢ c 2 ⁢ z 2 + a 1 ⁢ z 2 + a 2 ⁢ z 4 + a 3 ⁢ z 6 + a 4 ⁢ z 8 + … ⁢ , ( B ) y1 gives a position on an optical axis; x designates a perpendicular distance from the optical axis to the surface; k, c, and a1, a2, a3, a4, . . . are constants describing a surface of the lens to be moulded and z=|x|+b, wherein b is a constant with a value greater than 0 and less than 0.3 mm, which is a measure of a deviation of the shaping surface from the surface of the lens.