A computerized analysis of astigmatism after cataract surgery

We have performed a computerized analysis of postoperative changes in corneal astigmatism in 203 consecutive cases of extracapsular cataract extraction with posterior chamber intraocular lens implantation performed by one surgeon. Surgical technique was standardized consisting of a 140 degree posterior limbal incision with preplaced 9-0 silk and postplaced 10-0 nylon sutures. The average postoperative astigmatism was 1.60 D and the average surgically induced change in astigmatism 0.51 D after a mean follow-up of 5.4 months. When the axis of astigmatism was considered, cataract surgery on the average initially induced 2.2 D of with-the-rule astigmatism which gradually declined, stabilizing at 0.35 D against-the-rule 19 weeks postoperatively. An analysis of the natural history of astigmatism after cataract surgery helps to optimize the timing of spectacle prescription and postoperative intervention to correct excessive astigmatism. A computerized astigmatism analysis also provides rapid feedback to guide changes in surgical technique to minimize astigmatism.