Effect of Larger Corneal Horizontal Diameters on Astigmatic Effect of Main Corneal Incision in Cataract Surgery
Clear corneal incisions in cataract surgery create a variable amount of surgically-induced astigmatism (SIA). As refractive outcomes become more important, it is necessary to understand the factors impacting SIA. In this study, we evaluated the effect of the patient’s corneal horizontal diameter (white-to-white measurement, WTW) on SIA.
We performed a retrospective study of 7 patients (10 eyes) who had LenStar measurements performed before and after uncomplicated small-incision cataract surgery. All surgeries were performed through a temporal 2.2 mm clear corneal incision by a single surgeon. Patients with limbal-relaxing incisions or history of corneal pathology were excluded from analysis. We recorded the pre-operative WTW value and compared it to the SIA as calculated according to the Jaffe and Clayman method. Post-operative optical biometry measurements were performed 1-2 months following surgery.
SIA was plotted against WTW and best fit to a linear regression model. In our small population of eyes with WTW ranging from 11.74 mm to 12.79 mm, we found there was a trend suggesting that a larger WTW decreases the astigmatic effect of the SIA in cataract surgery (slope was - 0.5D/mm). However, due to the current population size, R2 was 0.02.
In this preliminary study, larger corneal horizontal diameters appeared to decrease the astigmatic effect of the main clear corneal incision. Enrollment of a larger population of patients is ongoing, and this study will be updated to further clarify this potential relationship with important implications for cataract surgery planning.