Long-term course of surgically induced astigmatism.

We performed an analysis of surgically induced astigmatism in 229 cases of extracapsular cataract extraction and posterior chamber lens implantation. The average length of follow-up for patients in this study was 34.4 months (2.87 years). We found that surgically induced astigmatism continued to change for at least three years after surgery. The preoperative astigmatism was found to have only minimal effect on the postoperative astigmatism if the corneal curvature was controlled with keratometry at the time of surgery. The optimal amount of with-the-rule astigmatism at three to five weeks postoperatively was found to be 0.75 diopter to 1.25 diopters for one surgeon and surgical technique.