Comparison of 13 formulas for IOL power calculation with measurements from partial coherence interferometry

Abstract

Background/aimsTo compare the accuracy of 13 formulas for intraocular lens (IOL) power calculation in cataract surgery.MethodsIn this retrospective interventional case series, optical biometry measurements were entered into these formulas: Barrett Universal II (BUII) with and without anterior chamber depth (ACD) as a predictor, EVO 2.0 with and without ACD as a predictor, Haigis, Hoffer Q, Holladay 1, Holladay 2AL, Kane, Næser 2, Pearl-DGS, RBF 2.0, SRK/T, T2 and VRF. The mean prediction error (PE), median absolute error (MedAE), mean absolute error and percentage of eyes with a PE within ±0.25, ±0.50, ±0.75 and ±1.00 diopters (D) were calculated.ResultsTwo hundred consecutive eyes were enrolled. With all formulas, the mean PE was zero. The BUII with no ACD had the lowest standard deviation (±0.343 D), followed by the T2 (0.347 D), Kane (0.348 D), EVO 2.0 with no ACD (0.348 D) and BUII with ACD (0.353 D) formulas. The difference among the MedAEs of all formulas was statistically significant (p<0.0001); the lowest values were achieved with the Kane (0.214 D), RBF 2.0 (0.215 D), BUII with and without ACD (0.218 D) and SRK/T (0.223 D). A percentage ranging from 80% to 88.5% of eyes showed a PE within ±0.50 D and all formulas achieved more than 50% of eyes with a PE within ±0.25 D.ConclusionAll investigated formulas achieved good results; there was a tendency towards better outcomes with newer formulas. Traditional formulas can still be considered an accurate option.

<p>VRF-G, a New Intraocular Lens Power Calculation Formula: A 13-Formulas Comparison Study</p>

“…With new SS-OCT biometers, similar results were also reported. [6][7][8] With respect with VRF-G formula, it is a newly developed formula based on theoretical optics with regression and ray-tracing components. We are unable to discuss the results due to lack of literature.…”

“…3 However, our results suggest that with an OLCR biometer, the improved 2.0 version is considerably more accurate, confirming reported outcomes by authors who used other biometer technologies. [6][7][8] In fact, it had the second lowest MAE for all AL subgroups, revealing its regularity across the entire AL range.…”

“… 6 The VRF formula results were similar to those obtained with the T2 formula. There are some conflicting results about which one of these two formulas perform better 7 , 8 , 18 – differences in published outcomes may be explained by differences in biometers used. The thick-lens vergence formula Næser 2 results were not among the best, in agreement with Savini et al 7 results.…”

“…2 Previous studies, using biometers based on partial coherence interferometry (PCI), swept-source optical coherence tomography (SS-OCT) or optical low-coherence interferometry (OLCR), revealed promising results with regard to some of these new formulas. [3][4][5][6][7][8][9] Kane formula seems to be the most accurate formula available, [4][5][6] with Barrett Universal II continuing to be a very reliable option (84% of eyes within 0.50D for Kane formula and 80% of for Barrett Universal II). 3,4 Very recently, EVO (version 2.0) also showed good results, being one of the most accurate formulas using both SS-OCT and PCI based biometers to obtain biometric data.…”

“…3,4 Very recently, EVO (version 2.0) also showed good results, being one of the most accurate formulas using both SS-OCT and PCI based biometers to obtain biometric data. 6,8 However, we are unaware of comparative studies including EVO (version 2.0) and PEARL-DGS, using an OLCR biometer.…”