EVALUATING SURGICALLY INDUCED ASTIGMATISM

Using a modification of vector analysis for calculating surgically ind uced astigmatism, we describe a simple method that divides the induced cylinder into two orthogonal components. This decomposition allows wi th-the-rule and against-the-rule astigmatic changes to be calculated f or individual case analysis, as well as for statistical analysis of ag gregate data. Because it is based on the true induced cylinder, as det ermined by optical principles, this method overcomes some of the probl ems associated with earlier methods of evaluating surgically induced a stigmatism.