The Clinical Research Of Different Incision Locations On Corneal Astigmatism In Cataract Surgery

Objective : To analyze the changes of corneal astigmatism and surgically induced astigmatism(SIA) after phacoemulsification with different locations of 2.8mm corneal incision.Method: 38 patients with 48 eyes were treated by phacoemulsification with a 2.8mm clear corneal incision. The patients were randomly divided into two groups according to different incision meridian: group A(incision at 12: 00); group B(incision at the steepest corneal meridian). The group B was divided into group B1(preoperative corneal astigmatism≤0.75D) and group B2(preoperative corneal astigmatism>0.75D).The visual acuity and corneal astigmatism were compared with preoperatively and 1week, 1 month, 3 months postoperatively, and the SIA were calculated by vector analysis.Results: Statistical analysis showed that the significant difference between the two groups of patients preoperative and postoperative uncorrected visual acuity(UCVA).Compared with the preoperative corneal astigmatism, the 1 week, 1 month, 3 months postoperatively corneal astigmatism increased significantly in A group(P<0.01, P<0.05,P<0.05). Compared with the preoperative corneal astigmatism, the 1 month, 3 monthspostoperatively corneal astigmatism decreased significantly in B group(P<0.01,P<0.01), but no significant difference between preoperative and 1 week postoperatively(P>0.05). The corneal astigmatism had significant difference between 1 week and 1month(P<0.01, P<0.01) both in A and B group, but not between 1 month and 3 months(P>0.05, P>0.05). There was no significant difference in the preoperative and postoperative corneal astigmatism in group B1(P>0.05, P>0.05, P>0.05). Compared with the preoperative corneal astigmatism, the 1 week, 1 month, 3 months postoperatively corneal astigmatism decreased in group B2, and there was significant difference at 1 month and 3 months postoperatively(P<0.01, P<0.01), but not at 1 week(P>0.05). 3 months after the surgery, the SIA was(0. 59±0. 29)D,(0. 55±0. 34)D in group A and B respectively. There was no significant difference(P>0.05).Conclusions: The corneal astigmatism after phacoemulsification with 2.8 mm corneal incisions will be stable at 1 month postoperative. To the patients with preoperative corneal astigmatism more than 0.75 D and less than 2.00 D, the 2.8 mm clear corneal incision placed on the steepest corneal meridian in phacoemulsification can reduced preoperative corneal astigmatism significantly, and patients can obtain a better visual acuity. To the patients with preoperative corneal astigmatism more than 0.25 D and less than 0.75 D, the 2.8 mm corneal incision placed on the steepest corneal meridian in phacoemulsification can not correct preoperative corneal astigmatism significantly.