Site of clear corneal incision in cataract surgery and its effects on surgically induced astigmatism

Clear corneal incision (CCI) is a commonly used surgical approach in cataract surgery. In this prospective study, we evaluated the effect of CCI site on surgically induced astigmatism (SIA) and other postoperative astigmatic changes. CCIs were constructed based on the steep meridian of the total corneal refractive power in the 4.0-mm-zone (TCRP4.0), and patients were divided into four groups: temporal, superotemporal, superonasal, and superior according to the site of the incision. TCRP4.0 analysis demonstrated a statistically significant reduction of astigmatism with superior incisions (P<0.001), and the combined mean polar values for SIA changed significantly in the temporal (Hotelling T-2=1.977), superotemporal (Hotelling T-2=0.544), superonsal (Hotelling T-2=1.066), and superior incision groups (Hotelling T-2=1.134) (all P<0.001). The posterior axis alignment should be considered in cataract surgery with CCI, and the SIA is affected by axis rotation, and incision orientation.