Astigmatic Correlation between the Automated Refractometry and Dual Scheimpflug Analyzer in Pseudophakic Eyes

Purpose: To examine the relationship between the refractive astigmatism by automated refractometry and the corneal astigmatism by a dual Scheimpflug analyzer in pseudophakic eyes. Methods: Prospectively, 75 patients (100 eyes) were enrolled in the present study. Refractive astigmatism was obtained by automated refraction. Corneal astigmatism was obtained using automated keratometry (ARK-530A) and dual Scheimpflug scanning analysis (Galilei G4). All refractive values were converted to the power vector components J0 and J45 for comparison and regression analysis of refractive versus corneal astigmatism. Bland-Altman plots were created to estimate the agreement between measurements. Results: The average astigmatism from each measurement was -1.11 ± 1.44 D (refractive astigmatism from automated refraction), -0.77 ± 1.06 D (corneal astigmatism from automated keratometry), -0.93 ± 1.02 D (simulated K from Galilei G4), and -1.11 ± 1.48 D (total corneal power from Galilei G4). Refractive J0 and keratometric J0 were significantly correlated (r = 0.557, p ≤ 0.001), as well as the corresponding J45 values (r = 0.655, p = 0.025). Refractive astigmatism and total corneal power components were also significantly correlated (J0: r = 0.618, p ≤ 0.001; J45: r = 0.608, p = 0.04). In the Bland-Altman plots, keratometric J0 and total corneal power J0 showed the best agreement. Conclusions: The accuracy of measurements for corneal refraction and astigmatism in pseudophakic eyes is higher using the dual Scheimpflug analyzer, especially for total corneal power. This value of astigmatism can take into account the refractive astigmatism of pseudophakic eyes and can be used in evaluating postoperative corneal astigmatism. J Korean Ophthalmol Soc 2016;57(3):361-368