Spherical Aberration of Astigmatic Corneas in a Cataract Population

PURPOSE: To study the distribution of spherical aberration (SA) in astigmatic corneas in a cataract population and the relationship between magnitude of corneal astigmatism and fourth-order corneal SA. METHODS: Data routinely collected using a Scheimpflug camera (Pentacam; Oculus Optikgerate GmbH) were ret-rospectively analyzed. Patients with a minimum age of 60 years were included. Total corneal SA (from anterior and posterior corneal surface) was obtained for a 6-mm cor-neal area aligned with the pupil center. Exclusion criteria were insufficient measurement quality, total deviation index (Belin/Ambrosio Deviation) greater than 1.60, and corneal thickness at the thinnest point of less than 490 & mu;m. One eye per patient was chosen randomly. Eyes were divided into low (& LE; 1.00 diopters [D]), moderate (> 1.00 to & LE; 2.00 D), and high (> 2.00 D) astigmatism groups according to the Scheimpflug measurements. RESULTS: A total of 528 eyes were included in this analysis. Low astigmatism was found in 129 patients, moderate astig-matism in 265 patients, and high astigmatism in 134 patients. Mean astigmatism was 0.68 & PLUSMN; 0.24, 1.45 & PLUSMN; 0.28, and 2.91 & PLUSMN; 0.95 D in the low, moderate, and high astigmatism groups, respectively. Mean corneal SA in patients with moderate and high astigmatism was higher than in the low astigmatism group. The difference reached the significance level for the comparison of low and high astigmatism groups (P = .023). The fourth-order SA increased gradually with the magnitude of astigmatism with a slope of 0.015. CONCLUSIONS: SA was significantly larger in the cataract population with high corneal astigmatism. The increase of positive sign SA with the magnitude of astigmatism sug-gests that patients with moderate to high astigmatism may benefit more from intraocular lenses with negative sign SA correction.