[Calculating the induced, computerized tomography measured corneal astigmatism after cataract surgery with small...

Small-incision cataract surgery with scleral tunnel incision and one-stitch horizontal or sutureless wound closure has been found to be an effective way to reduce postoperative astigmatism and to guarantee greater stability of the wound with rapid visual rehabilitation. In some studies surgically induced astigmatism by different wound constructions and wound-closure techniques has been compared to determine the astigmatism induced. Different calculation methods were used leading to different results. Therefore, we evaluated the induced astigmatism in 50 patients operated on by scleral tunnel incision, phacoemulsification with PCL implantation and single-stitch wound closure. We analyzed induced astigmatism on the first postoperative day and 3 months postoperatively by different methods: the simple subtraction method (0.91 and 0.30 D), Naeser's polar value method (-0.74 and -0.75 D), the vector analysis method of Jaffe (2.53 and 1.19 D) and two calculations described by Cravy. Depending on the formula used, different results were obtained. The subtraction method disregards axis change and is less precise. The vector analysis methods obtain the highest values for induced astigmatism and seem to be the most precise for evaluating the real amount of induced postoperative astigmatism.