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AimTo compare the preoperative biometric data and the refractive accuracy of cataract surgery among major surgical sites in a nationwide multicentre study.MethodsWe prospectively obtained the preoperative biometric data of 2143 eyes of 2143 consecutive patients undergoing standard cataract surgery at major 12 facilities and compared the preoperative biometry as well as the postoperative refractive accuracy among them.ResultsWe found significant differences in most preoperative variables, such as axial length (one-way analysis of variance, p=0.003), anterior chamber depth (pConclusionsRegional divergences of the preoperative biometry were not necessarily negligible, and the optimised intraocular lens power calculation formula was individually different among the 12 facilities. Our findings highlight the importance of individual optimisation of these formulas at each facility, especially in consideration of these biometric variations.Trial registration numberClinical Trial Registry; 000039976.

AimsTo provide clinical guidance on the use of intraocular lens (IOL) power calculation formulas according to the biometric parameters.Methods611 eyes that underwent cataract surgery were retrospectively analysed in subgroups according to the axial length (AL) and corneal power (K). The predicted residual refractive error was calculated and compared to evaluate the accuracy of the following formulas: Haigis, Hoffer Q, Holladay 1 and SRK/T. Furthermore, the percentages of eyes with ≤±0.25, ≤±0.5 and 1 dioptres (D) of the prediction error were recorded.ResultsThe Haigis formula showed the highest percentage of cases with ≤0.5 D in eyes with a short AL and steep K (90%), average AL and steep cornea (73.2%) but also in long eyes with a flat and average K (65% and 72.7%, respectively). The Hoffer Q formula delivered the lowest median absolute error (MedAE) in short eyes with an average K (0.30 D) and Holladay 1 in short eyes with a steep K (Holladay 1 0.24 D). SRK/T presented the highest percentage of cases with ≤0.5 D in average long eyes with a flat and average K (80.5% and 68.1%, respectively) and the lowest MedAE in long eyes with an average K (0.29 D).ConclusionOverall, the Haigis formula shows accurate results in most subgroups. However, attention must be paid to the axial eye length as well as the corneal power when choosing the appropriate formula to calculate an IOL power, especially in eyes with an unusual biometry.

Aims: To optimise the relationship between the actual and predicted refractive outcomes following phacoemulsification and axial length of the eye. Four intraocular lens (IOL) power calculation formulae were compared: SKR-T, Holladay I, Hoffer-Q and Haigis. Optical axial length transformation based on the original calibration of the IOLMaster was tested to improve the predictability of outcomes. Methods: The refractive outcomes of 155 eyes of 120 patients using the IOLMaster were reviewed following phacoemulsification. After optimising the IOL constants, the prediction error (PE; achieved spherical equivalent − calculated spherical equivalent) of each of the formulae was calculated for each eye and then correlated to the axial length of the eye with and without the optical transformation. Keratometry measurements of the IOLMaster were tested by transforming to that of standard autokeratometry. This was validated in a second group of 90 eyes. Results: The PE of all but the Haigis triple optimised formula were found to be positively correlated to the axial length. The optical and keratometric transformation statistically significantly reduced this correlation, leading to fewer PE at all axial lengths. PE per millimetre axial length was 0.06 D/mm (SRK-T), 0.16 D/mm (Hoffer-Q), 0.14 D/mm (Holladay I), 0.11 D/mm (Haigis single) and −0.02 D/mm (Haigis triple). Following transformation, best case PE was reduced to −0.01 D/mm (SRK-T), 0.08 D/mm (Hoffer-Q), 0.01 D/mm (Holladay I), 0.01 D/mm (Haigis single) and −0.01 D/mm (Haigis triple). Conclusion: Transforming the IOLMaster measurement into the optical axial length while compensating for its keratometry measurement was able to improve the predictability of outcomes at extreme axial lengths without further modification to the standard IOL formulae.

Cataract surgery has evolved from the ancient technique of ‘couching’ with suboptimal results to femtosecond laser-assisted phacoemulsification with excellent visual results. It is the most frequently performed surgery in the world.1 The recent advances in surgical techniques have increased the safety and efficacy of this procedure. There have also been improvements in the techniques to measure ocular biometry and methods to calculate intraocular lens (IOL) power resulting in high expectations for increasingly better outcomes from surgeons and patients. The accuracy of the refractive end point depends on the potential errors from a multitude of factors, which are involved in the calculation of the IOL power, aside from the surgical aspects themselves. These variables include the axial length, corneal power measurements, assumed corneal refractive index, lens position and anterior chamber depth.2 Although these factors are closely related to each other, and a change in one may affect the other, they have been assumed to be relatively independent factors for the purposes of the mathematical formulae used to perform IOL power calculations. Hence, there is potential for errors …