A method for calculating the required cylindrical power of a toric implant
by using both the measured pre-operative corneal/ocular astigmatism and
the predicted surgically-induced astigmatism. The post-operative
corneal/ocular astigmatism is predicted using power vector analysis of
the surgical technique employed by the surgeon. Such a method provides a
more accurate method of calculating the required spherocylindrical
refractive power of the implant. The method can be implemented manually,
but preferably is automated by implementation on a computer through
appropriate software.