Choice of the site of incision for cataract surgery without suture according to preoperative astigmatism

PURPOSE: To compare surgically induced astigmatism, postoperative astigmatism and uncorrected visual acuity after cataract surgery depending on the site of a 4 mm sutureless incision (superior scleral or corneal temporal) and on the preoperative astigmatism. METHODS: According to preoperative astigmatism and to the site of incision 4 groups have been distinguished. Group I: with-the-rule preoperative astigmatism and superior scleral incision, group II: with-the-rule preoperative astigmatism and corneal temporal incision, group III: against-the-rule preoperative astigmatism and superior scleral incision, group IV: against-the-rule preoperative astigmatism and temporal incision. The patients had a preoperative and postoperative (Day 1, 8, 30, 180, 360) keratometry. Surgically induced astigmatism, preoperative and postoperative astigmatism have been expressed according to Naeser method. The uncorrected visual acuity at Day 30 has been compared in each group. RESULTS: Preoperative astigmatism was similar in the four groups. Surgically induced astigmatism was -0.18 diopter (D) at day 30 and -0.41 D at day 360 for the scleral incisions and +0.60 D at day 30 and +0.33 D at day 360 for the temporal incisions. The postoperative astigmatism was +0.5 D at day 30 and +0.27 at day 360 for the group I and +1.22 D at day 30 and +0.95 D at day 360 for group II. There was no statistical difference in the uncorrected visual acuity. Postoperative astigmatism was -0.8 D at day 30 and -1.03 D at day 360 in group III and -0.04 D at day 30 and -0.31 D at day 360 in group IV. The visual acuity was significantly better in group IV than in group III. CONCLUSION: In cases of preoperative with-the-rule astigmatism < or = 0.75 D the two sites of incisions are possible. In cases of WTR astigmatism over 0.75 D we perform a superior scleral approach. In cases of against-the-rule astigmatism the temporal incision is the only one to consider.