Comparing Total Keratometry Measurement on the IOLMaster 700 With Goggin Nomogram Adjusted Anterior Keratometry

PURPOSE: To compare “total keratometry” measurements with Goggin nomogram adjusted anterior keratometry (GNAK) for toric intraocular lens calculation. METHODS: Routine biometry provided measured total keratometry values from which astigmatism was derived. The Goggin nomogram was applied to anterior keratometry values on the same eyes to provide nomogram-adjusted anterior keratometry values (GNAK) that estimate total corneal astigmatism. The agreement between total keratometry and GNAK was analyzed. RESULTS: Overall, in 46 eyes there was no statistically significant difference between median GNAK and total keratometry power values ( P = .746). No statistically significant difference remained in against-the-rule and oblique subgroup analyses. Absolute and signed steep axis of astigmatism was statistically significantly different for GNAK and total keratometry in the overall analysis ( P < .001 and = .029, respectively) and for against-the-rule and oblique subgroup analyses. The with-the-rule subgroup showed a statistically significant difference in astigmatic power and no significant signed steep axis difference between GNAK and total keratometry. CONCLUSIONS: Total keratometry appears able to measure total corneal astigmatism to match closely (clinically and statistically) GNAK estimation of that parameter. This indicates that it would be safe and reasonable to use total keratometry data for planning of cataract surgery with toric IOLs. [ J Refract Surg. 2018;34(8):521–526.]