Expected effects of surgically induced astigmatism on AcrySof toric intraocular lens results

Purpose

To evaluate the expected effects of including surgically induced astigmatism (SIA) in surgical planning for the AcrySof toric intraocular lens (IOL) (Alcon Laboratories, Inc.).

Setting

Private practice, Mesa, Arizona, USA.

Methods

Keratometric data were obtained for a large patient population (806 eyes) with preoperative corneal astigmatism of 2.50 diopters (D) or less. Anticipated residual astigmatism was calculated using nominal SIA values in the AcrySof Toric IOL Calculator for superior and temporal incisions. Anticipated residual astigmatism was also calculated without considering SIA in the planning process but with a nominal value applied when calculating the surgical result.

Results

Using a 0.50 D SIA value for superior or temporal incisions, there was a statistically, but not clinically significant, difference (mean approximately 0.05 diopter [D]) in the anticipated residual astigmatism by incision location (P<.05). Anticipated residual astigmatism, when including or not including SIA in the planning process, was statistically significantly different by IOL and incision location (P<.05), with anticipated differences that were clinically significant (>0.50 D) for all toric IOLs. These large differences appeared to be driven by changes in IOL selection as a result of including SIA in the AcrySof Toric IOL Calculator.

Conclusions

With the AcrySof toric IOL, consideration of SIA from temporal or superior incisions resulted in statistically and clinically significantly lower anticipated residual astigmatism. The most important effect of including SIA appears to be more appropriate IOL selection.