Accuracy of the Goggin Nomogram for 0.50 D Steps in Toric IOL Cylinder Power Calculation

Abstract

To examine the accuracy of the cylinder power choice for toric intraocular lenses (IOLs) using the Goggin Nomogram, which adjusts anterior keratometric astigmatic power values for the likely effect of posterior corneal and non-corneal, non-lenticular astigmatism. A consecutive, retrospective case series was based at the Queen Elizabeth Hospital and Ashford Advanced Eye Care in Adelaide, Australia. A total of 586 consecutive eyes of 586 patients underwent phacoemulsification surgery with implantation of a Zeiss AT TORBI 709MP or AT LISA Tri Toric 939 MP toric IOL, calculated using the Goggin Nomogram. The median absolute magnitude of error and geometric mean astigmatic correction index in consecutive eyes with toric IOL cylinder powers of 1.00 to 3.00 diopters (D) were analyzed. Overall, all eyes receiving IOL cylinder powers of 1.00 to 3.00 D inclusive had a median magnitude of error value of 0.19 D (IQR: 0.31) and astigmatic correction index value of 1.03 (IQR: 0.33). For eyes with with-the-rule, against-the-rule, and oblique astigmatism, the median magnitude of error was 0.18 D (interquartile range [IQR]: 0.29), 0.19 D (IQR: 0.31), and 0.17 D (IQR: 0.39), respectively, and the astigmatic correction index was 1.06 (IQR: 0.28), 1.01 (IQR: 0.35) and 1.08 (IQR: 0.32), respectively. Goggin Nomogram adjusted keratometry provided optimal refractive astigmatic outcome in IOL cylinder powers of 1.00 to 3.00 D in eyes with with-the-rule, against-the-rule, and oblique astigmatism. Goggin Nomogram adjusted keratometry compensates for both posterior corneal astigmatism and any other source of ocular astigmatism. [J Refract Surg. 2022;38(5):298–303.]