Possible factors modifying the surgically induced astigmatism in cataract surgery

To investigate possible modifiers of the surgically induced astigmatism with special reference to age, gender, preoperative astigmatism, and the intraocular pressure.

Data for one hundred and one cataract patients operated on with extracapsular cataract extraction and intraocular lens implantation were prospectively recorded and followed for six years. Different explanatory variables like age, gender, preoperative astigmatism and postoperative intraocular pressure (IOP) were considered. Astigmatic changes were calculated as Naeser's polar values.

The surgically induced astigmatism was not significant at one year, but was significantly increased 3- and 6-years postoperatively. At the same time the keratometric axis made a shift toward against-the-rule astigmatism. The postoperative mean-IOP was lower at all controls. Multiple regression analysis showed that a large preoperative astigmatism, a low postoperative IOP, and high age resulted in more surgically induced astigmatism against-the-rule.

The length and the architecture of the incision are known to have an influence on the surgically induced astigmatism in cataract surgery. In the present study we used a multiple regression analysis model to show a significant correlation between the surgically induced astigmatism and age, preoperative astigmatism, and postoperative IOP.