To analyze the accuracy of the Holladay 2 formula, which has been proposed as an improvement over the original Holladay formula. This retrospective analysis comprised 317 eyes operated on by 1 surgeon using 1 technique and 1 intraocular lens style in a specialty practice. Because the Holladay 2 formula has yet to be published, its accuracy can only be analyzed using the commercially available Holladay IOL Consultant computer program to compare it to the Holladay 1, Hoffer Q, and SRK/T formulas. Defined axial length ranges were analyzed individually. A lower mean absolute error (MAE) trend was found for the average length eye (22.0 to 24.5 mm) by the Holladay 1 and Hoffer Q formulas. For short eyes (< 22.0 mm), the Hoffer Q and Holladay 2 perform better. The SRK/T consistently showed a trend toward the lowest MAE in all long eyes (>24.5 mm) as well as the subdivisions of medium long (24.5 to 26.0 mm) and very long (>26.0 mm). The Holladay 2 trended toward the least accurate (MAE) of the 4 formulas in all ranges of axial length except the shortest and the very longest. It appears to perform poorer in average and medium long eyes. Although the Holladay 2 formula has improved its MAE accuracy in short eyes, it was not more accurate than the Hoffer Q. The changes made in the formula to effect this improvement in MAE seem to have sacrificed the accuracy of the original Holladay formula in eyes with average and medium long axial lengths.

Methods to attempt more accurate prediction of intraocular lens power in refractive surgery eyes are many, and none has proved to be the most accurate. Until one is identified, a spreadsheet tool is available and can be used. It automatically calculates all the methods for which data are available on a single sheet for the patient's chart. The various methods and how they work are described.

To compare axial length (AL), anterior chamber depth (ACD), and keratometric (K) measurements of 2 laser biometers. Private practices, Lynwood and Santa Monica, California, USA. In this prospective comparative observational study of eyes with cataract and eyes with a clear lens, AL, ACD, and K measurements were performed using an IOLMaster biometer, which uses partial coherence interferometry (PCI), and a Lenstar LS 900 biometer, which uses optical low-coherence reflectometry (OLCR). Intraocular lens (IOL) power calculation was performed using the Haigis formula. The IOL prediction error was calculated for each eye. The study evaluated 50 eyes with cataract and 50 eyes with a clear lens. There was a good correlation between AL, ACD, and K measurements in the cataractous eyes (r = 0.9993, 0.9667, and 0.9959, respectively) and in eyes with a clear lens (r = 0.9995, 0.8211, and 0.9959, respectively). The OLCR unit measured a slightly longer AL in the cataract group and clear lens group (mean difference 0.026 mm and 0.023 mm, respectively), a deeper ACD (0.128 mm and 0.146 mm, respectively), and a flatter K (-0.107 diopter [D] and -0.121 D, respectively). The differences were statistically significant (P<.0001). The mean absolute error in IOL power prediction was 0.455 D +/- 0.32 (SD) with the OLCR unit and 0.461 +/- 0.31 D with the PCI unit (P>.1). Measurements were comparable between the OLCR device and the PCI device. A slight decrease (0.050) in the a(0) constant is recommended if the Haigis formula is used.

To investigate agreement between the IOLMaster 700 based on swept-source optical coherence tomography (SS-OCT) and the Lenstar LS 900 based on optical low-coherence reflectometry (OLCR). Private practice, Castrop-Rouxelle, Germany. Prospective evaluation of diagnostic test. Axial length (AL), keratometry (K), anterior chamber depth (corneal epithelium to lens) (ACD), lens thickness, and central corneal thickness (CCT) were measured in 183 eyes of 183 patients. Analyses used a paired t test, Pearson correlation coefficient (r), and Bland-Altman plots. Intraocular lens (IOL) power calculations were compared using the Hoffer Q, Holladay 1, and SRK/T formulas. The difference in the mean AL between SS-OCT and OLCR was statistically significant but clinically insignificant (23.61 mm ± 1.27 [SD] and 23.60 ± 1.27 mm, respectively; P < .0001); the agreement and correlation were excellent. The mean K with OLCR was flatter by 0.02 diopter (D) than the mean K with SS-OCT, 43.82 ± 1.43 diopters (D) and 43.84 ± 1.43 D, respectively; the difference was not statistically significant. The mean ACD with SS-OCT was deeper by 0.03 mm than the mean ACD with OLCR, 3.22 ± 0.44 mm and 3.19 ± 0.44 mm, respectively; the difference was statistically significant (P < .001) but clinically insignificant. The differences in the mean lens thickness (OLCR 4.63 ± 0.44 mm and SS-OCT 4.59 ± 0.43 mm) and the mean CCT (OLCR 559 ± 37 μm and SS-OCT 554 ± 36 μm) were not statistically significant. There was no statistically significant difference between the median absolute errors of the 3 formulas. Agreement between SS-OCT and OLCR was very good. The clinically insignificant but statistically significant differences in AL, ACD, and lens thickness did not reflect a statistically significant difference in IOL power calculation using 3 third-generation formulas. Proprietary or commercial disclosures are listed after the references.