ABSTRACT
Background: Location of incision has a significant impact on surgical outcome. It has been reported that temporal incisions induce less astigmatism than superior incisions indicating the importance of incision location. The objective of the present study was to study the effect of surgical induced astigmatism in superior versus temporal incision in small incision cataract surgery cases. Methods: 100 patients of cataract attending to Sarojini Devi eye hospital with the rule and against the rule astigmatism were included in the study. The astigmatic profile and the effect of surgical incision on astigmatism were studied. A prospective study was done in which patients were divided into two groups. MSICS was performed with superiorly located incision in group I and temporally located incision in group II. Results: Out of the total 100 patients undergoing MSICS, 59 patients had ATR, 36 patients had WTR and 5 patients had no astigmatism. Thus the pre-operative astigmatic profile shows that ATR is more common type of astigmatism in this group. Among 50 patients in superior incision group, 18 had pre-operative WTR, 29 had ATR and 3 did not have astigmatism. Postoperatively the no. of patients with WTR decreased to 10, the no. of patients with ATR increased to 35 showing that superior incision flattens vertical meridian and steepens the horizontal meridian causing ATR shift. Among 50 patients in temporal incision group, 18 had pre-operative WTR, 30 had ATR and 2 did not have astigmatism. Post operatively the no of patients with WTR increased to 25, the no of patients with ATR decreased to 20. Conclusions: Placement of incision on steep axis reduces pre-existing astigmatism. Thus in ATR astigmatism it is placed temporally and in WTR astigmatism it is placed superiorly. Thus a simple modification in incision placement can minimize surgically induced astigmatism and reduce pre-existing astigmatism.
ABSTRACT
We analysed postoperative corneal astigmatic changes to know that preoperative astigmatism was able to decreased according to the location of incision in sutureless cataract surgeries. We divided 70 patients, 81 eyes that scleral pocket incision, phacoemulsification, and posterior chamber intraocular lens implantation was performed into two groups. The one is the preoperative with-the-rule(WTR)astigmatism more than 1 diopter(D) with superior incision, and the other is the preoperative WTR less than 1D or against-the-rule (ATR) astigmatism with temporal incision. We followed up the corneal astigmatic chnges until six months postoperatively. According to the results of algebraic analysis, in the superior incision group, postoperative astigmatic changes showed WTR decrease of 0.43D immediately, which advanced toward ATR decrease of 0.41D immediately, which keep up ATR decrease and showed ATR decrease of 0.44D at 6 months. According to the results of vector analysis, surgical inducced corneal astigmatism was o.69D in superior incision group and 0.50D in temporal incision group at postoperative 1day. It was 0.98D in superior incision group and 0.57D in temporal incision group at postoperative 6 months. We could decrease preoperative corneal astigmatism with performing incision at the position of greater corneal curvature. Temporal incision group showed less surgical induced astigamatic changes than superior incision.