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Review Cataract Surgery Progress in Modern Cataract Surgery – New Steps and Algorithms for Precise Measuring and Intraocular Lens Calculations Fritz H Hengerer, Gerd U Auffarth and Ina Conrad-Hengerer Department of Ophthalmology, Ruprecht-Karls-University Heidelberg, Germany I n standard cataract surgery, one of the major goals is to reach target refraction. Based on keratometry measurements, axial length and anterior chamber depth, most of the intraocular lens calculation formulae are suitable to achieve this aim. Further evaluation of corneal refractive parameters like anterior and posterior corneal surface by Scheimpflug devices led to a significant enhancement of precision in astigmatic and post-refractive surgery cases. Keywords Cataract surgery, intraocular lens (IOL), imaging, corneal refractive power analysis Disclosure: Fritz H Hengerer, Gerd U Auffarth and Ina Conrad-Hengerer declare no financial interests in the topic mentioned in this article. Acknowledgements: The authors thank Jörg Iwanczuk from Oculus for technical support. Compliance with Ethics: This study involves a review of the literature and did not involve any studies with human or animal subjects performed by any of the authors. Authorship: All named authors meet the International Committee of Medical Journal Editors (ICMJE) criteria for authorship of this manuscript, take responsibility for the integrity of the work as a whole, and have given final approval to the version to be published. Open Access: This article is published under the Creative Commons Attribution Noncommercial License, which permits any non-commercial use, distribution, adaptation and reproduction provided the original author(s) and source are given appropriate credit. Received: 27 October 2017 Accepted: 8 December 2017 Citation: European Ophthalmic Review, 2017;11(2):95–8 Corresponding Author: Ina Conrad-Hengerer, Department of Ophthalmology, Ruprecht-Karls-University Heidelberg, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany. E: Support: The publication of this article was supported by Oculus. Cataract surgery had undergone major improvements in different areas over the last 10 years. New intraocular lens (IOL) designs and fourth generation IOL formulae are available, allowing spectacle independence for many patients. Femtosecond laser-assisted cataract surgery (FLACS) has been introduced, and the options seen on television and web-based sources have increased patients’ understanding and raised their expectations. Cataract surgeons, as well as the manufacturers of optical biometers and diagnostic equipment, recognized this and consider the corneal optical conditions and evaluate possible ocular surface diseases. In naïve eyes with senile cataract measurement of basic parameters like axial length (AL), keratometry and anterior chamber depth (ACD) were used to calculate the IOL power prior cataract surgery. Many cataract surgeons recognise these needs today while performing FLACS by: using new aspheric, toric and multifocal IOL designs; minimising incision size; and taking advantage of the new fourth generation IOL calculation formulae. Whilst the aim of this article is not to compare the precision and benefits of new IOL power formulae, this review will look beyond this, while pointing out other sources which may influence the quality of patients’ vision. In Table 1, a summary of fourth generation to standard formulae and their applications are listed. These formulae reduce mean absolute error (MAE), meaning more patients achieve final results within 0.5 D, 0.75 D and 1 D of the expected target refraction. But is this still enough to satisfy all patients’ expectations today? Beyond intensive and individual patient consultation with regard to premium IOLs, such as multifocal or multifocal toric IOLs, intensive pre-operative assessment of corneal and retinal conditions is indispensable. In recent years, many different optical biometers have been launched to provide, besides the basic necessary parameters like AL and anterior keratometry (ant K’s), additional information such as ACD, posterior keratometry (post K’s), total corneal power (TCP) and total corneal refractive power (TCRP), lens thickness (LT), horizontal-white-to-white (HWTW), for IOL power calculation. For an enhanced evaluation of the corneal shape some devices provide topography and tomography. Using this additional information, it is now possible to produce a more precise IOL power calculation and an enhanced preop assessment before performing premium cataract surgery. Table 2 lists the currently available optic biometers. In our university eye clinic, we are using the latest, to date, optical coherence tomography (OCT), the IOL Master 700 ® (Zeiss, Oberkochen, Germany) and the new Pentacam ® AXL (Oculus, Wetzlar, Germany). The Pentacam AXL is a Scheimpflug-based anterior segment tomographer with a built-in optical biometer. The Pentacam has proven to provide precise keratometry of the anterior and posterior corneal surface, which is the key-parameter for accurate IOL power TOU CH MED ICA L MEDIA 95