Assessment of the influence of keratometry on intraocular lens calculation formulas in long axial length eyes

Abstract

Purpose: Hyperopic surprises tend to occur in axial myopic eyes and other factors including corneal curvature have rarely been analyzed in cataract surgery, especially in eyes with long axial length (≥ 26.0 mm). Thus, the purpose of our study was to evaluate the in uence of keratometry on four different formulas (SRK/T, Barrett Universal II, Haigis and Olsen) in intraocular lens (IOL) power calculation for long eyes. Methods: Retrospective case-series. 180 eyes with axial length (AL) ≥ 26.0 mm were divided into 3 keratometry (K) groups: K ≤ 42.0 D (Flat), K ≥ 46.0 D (Steep), 42.0 < K < 46.0 D (Average). Prediction errors (PE) were compared between different formulas. Multiple regression analysis was performed to investigate factors associated with the PE. Results: The mean absolute error was higher for all evaluated formulas in Steep group (ranging from 0.66 D to 1.02 D) than the Flat (0.34 D to 0.67 D) and Average groups (0.40 D to 0.74D). The median absolute errors predicted by Olsen formula were signi cantly lower than that predicted by Haigis formula (0.42 D versus 0.85 D in Steep and 0.29 D versus 0.69 D in Average) in Steep and Average groups (P = 0.012, P < 0.001, respectively). And the Olsen formula demonstrated equal accuracy to the Barrett II formula in Flat and Average groups. The predictability of the SRK/T formula was affected by the AL and K, while the predictability of Olsen and Haigis formulas was affected by the AL only. Conclusions: Steep cornea has more in uence on the accuracy of IOL power calculation than the other corneal shape in long eyes. Overall, both the Olsen and Barrett Universal II formulas are recommended in long eyes with unusual keratometry.

Efficacy of corneal curvature on the accuracy of 8 intraocular lens power calculation formulas in 302 highly myopic eyes

“…This is because some previous studies have reported the performance of conventional formulas in different ranges of corneal curvature. 15,28 In conclusion, the EVO 2.0, Kane, and RBF 3.0 formulas showed better accuracy in high myopia eyes with a flat and steep K, whereas Hoffer QST showed a myopic shift in the flat K group and the highest accuracy in the normal K group. For long eyes with the AL ≤28 mm, all IOL formulas performed well in the flat K group because of the refractive compensation.…”

“…This is because some previous studies have reported the performance of conventional formulas in different ranges of corneal curvature. 15,28…”

Accuracy of seven intraocular lens power calculation formulas: according to corneal power

“…Even for the best-performing formulas, such as the BUII 21 and Olsen 11,21, the percentage of eyes with a PE within ± 0.50 D was only approximately 70%. It has been shown in previous studies that some new-generation formulas had higher accuracy in long AL subgroups, such as the Kane [13,27] and EVO2.0 [13] formulas. Whether these formulas have higher accuracy in eyes with a long AL and steep corneal power requires further study.…”

Comparison of keratometric values and anterior segment parameters measured using Scheimpflug Sirius topography and Lenstar biometry

“…Lenstar is indispensable in the diagnosis and treatment of eye diseases. Keratometry (K), AL, and ACD are important variables in IOL power calculation formulas [12][13][14]. Newer algorithms, such as the Holladay 2 and Barrett Universal II formulas, use corneal diameter (CD) and lens thickness (LT) to enhance accuracy [15,16].…”