J Korean Ophthalmol Soc.  2021 Sep;62(9):1181-1188. 10.3341/jkos.2021.62.9.1181.

Intraocular Lens Power Calculation According to the Difference between Anterior and Total Keratometry Using Scheimpflug Imaging

  • 1Department of Ophthalmology, Dankook University Hospital, Dankook University College of Medicine, Cheonan, Korea


We investigated the change in the absolute error according to the difference between anterior and total keratometry, to determine the criterion for the difference in keratometry, and to determine the indication for using total keratometry.
Sagittal and total refractive power were measured with 2-, 3-, and 4-mm Pentacam® rings, and the absolute error of each was calculated in patients who underwent cataract surgery in our hospital. The correlation between the difference value the sagittal minus the total refractive power and each absolute error was analyzed by simple regression analysis. The analysis was performed by dividing the patients into two groups based on 0.6, which is the average of the difference between the sagittal and total refractive power for the 3-mm ring.
Sagittal power was larger than total refractive power for all rings and the absolute error obtained by applying the total refractive power was larger than the sagittal power for the 2- and 4-mm rings (p < 0.001). The simple regression analysis revealed that the absolute error using sagittal power was positively correlated with the difference between sagittal power and total refractive power. In the group with less than 0.6, the absolute error using the total refractive power of all rings was larger than the sagittal power (p < 0.001). In the group exceeding 0.6, the absolute error using the total refractive power was less than using the sagittal power for the 3 mm ring (p = 0.028).
The greater the difference between sagittal and total refractive power, the greater the absolute error using sagittal power. Accuracy was higher in the group exceeding 0.6 after applying total refractive power measured at the 3 mm ring compared to sagittal power.


Intraocular lens power, Sagittal power, Scheimpflug, Total refractive power
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