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Bicylindric intraocular lens power calculation method: using both flat and steep k readings to improve IOL power prediction

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Session Details

Session Title: Cataract
Session Date/Time: Saturday 10/02/2018 | 08:30-11:00
Paper Time: 08:54
Venue: Blue Hall

First Author: J.Calvo-Sanz SPAIN
Co Author(s): A. Arias-Puente  C. Bonnin-Arias               

Abstract Details


Intraocular lens (IOL) power calculation for cataract surgery is generally performed using biometrical measurements such as mean keratometry (Km) and axial length (AL), and several regression formulas to obtain IOL power to get emmetropia in spherical equivalent (SE). This work presents a new method of IOL power calculation based on the use of both keratometry readings, steep and flat, to improve the reliability and precision of the prediction of refractive outcomes.


Instituto de Ciencias Visuales - Hospital La Zarzuela - Madrid - Spain


In this study were included patients without ocular pathology or previous ocular surgery, AL greater than 21mm, flat keratometry axis between 0 and 90º and without complications in intra and postoperative process. Optical biometry was performed using IOLMaster700 (Carl Zeiss Meditec - Alemania) and Haigis formula was used to calculate IOL power in order to acquire emmetropia after the implantation of an acrylic monocular lens. In the surgical procedure, the main corneal incision was 2.8 mm diameter performed at 135º in a clear paralimbal cornea. Refractive outcomes were compared with the bicylindric prediction and Haigis prediction 4 weeks after surgery.


This study included 62 eyes of 62 participants, 25 females and 37 males, with a mean age of 71.63 ± 7.21 years (49 to 87 years.). The mean difference between Haigis SE prediction (HSE) and Achieved SE (ASE) was -0.117 D (p=0.002), and the mean difference between Bicylindric SE (BSE) prediction and ASE was -0.054 D (p=0.009). Linear correlation between BSE and ASE was positive and statistically significant (R=0.809, p<0.001), but correlation between HSE and ASE was not statistically significant (R=0.083, p=0.520). The percentage of patients who achieved predicted refraction by Haigis and Bicylindric method was 76.70% and 84.30% respectively.


The bi-cylindrical method of intraocular lens power calculation is a simple and reliable way to predict the final refractive outcomes in patients with low corneal astigmatism. Bicylindric method showed an improvement in the refractive management of cataract patients providing refractive outcomes up to 8% more accurate than classical IOL calculation methods.

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