Influence of corneal diameter on surgically induced astigmatism in small-incision cataract surgery

Objective Clear corneal incisions (CCI) in cataract surgery create a variable amount of surgically induced astigmatism (SIA). As refractive outcomes become increasingly important, it is necessary to understand factors that impact SIA and refractive surprises. In this study, we evaluate the effect of horizontal corneal diameter (white-to-white, WTW) on SIA in 2.2 mm small-incision cataract surgery. Design Prospective study at an academic-university-based outpatient clinic (Duke Eye Center). Participants We enrolled adults ≥18 years of age without prior corneal surgery or corneal pathology undergoing cataract surgery with a single surgeon (R.R.V.). Methods All surgeries were uncomplicated and performed through a manually constructed, limbal, temporal, or superotemporal 2.2 mm CCI. Enrolled participants received standard-of-care evaluations and postoperative management. SIA was calculated at the first postoperative month using the Jaffe and Clayman vector analysis equation. Results We enrolled 43 subjects (55 eyes) with a mean age of 71 years with WTW corneal diameter values ranging from 11.34 to 12.99 mm obtained from Lenstar® (Haag-Streit Group, Koeniz, Switzerland). Postoperative SIA ranged from 0.072 to 1.6 D (mean 0.47 D, standard deviation 0.33 D). SIA was plotted against WTW and best fit to a linear regression model with a slope of −0.056 and an R2 value of 0.006. Conclusions In this prospective study, WTW diameter had minimal effects on the SIA in uncomplicated small-incisional cataract surgery through a 2.2 mm temporal or superotemporal CCI with a single surgeon. Our findings suggest that corneal diameter does not play a clinically significant role in this population undergoing small-incisional cataract surgery.