Comparative Study of Surgically Induced Astigmatism in Different Types of Cataract Incision.

Background: Cataract remains the leading cause of blindness in India. Advances in cataract surgery have transformed it from a purely vision-restoring procedure into a refractive surgery, with a major determinant of postoperative success being surgically induced astigmatism (SIA). Aim: To evaluate the incidence and pattern of post-surgical astigmatism in relation to three types of incisions: superior sclero-corneal valve incision (SSC) in manual small incision cataract surgery, and superior (SCC) and temporal clear corneal valve incisions (TCC) in phacoemulsification surgery. Methods: A comparative study was conducted on 120 patients undergoing cataract surgery, divided equally into three groups (SSC, SCC, TCC). Keratometry readings were recorded preoperatively and postoperatively at 1, 3, and 6 weeks. Surgically induced astigmatism was analyzed across groups using statistical tests for significance. Results: SSC and SCC incisions predominantly induced against-the-rule (ATR) astigmatism, whereas TCC incision more commonly resulted in with-the-rule (WTR) astigmatism. While superior incisions showed greater ATR shift, temporal incisions demonstrated earlier wound stability and lower mean postoperative astigmatism. Paired comparisons showed statistically significant changes in the TCC group at week 1 (p<0.05), while SSC showed highly significant differences in the horizontal meridian. Conclusion: Temporal clear corneal incisions induce lower and more favorable astigmatism compared to superior approaches, making them advantageous for patients with pre-existing ATR astigmatism. Superior incisions, however, may be beneficial in cases of WTR astigmatism. Individualized incision planning is therefore essential to optimize visual outcomes.