To view this page ensure that Adobe Flash Player version 11.1.0 or greater is installed.
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
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: firstname.lastname@example.org
Support: The publication of this article was supported
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