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Agreement between VERION image guided system and other keratometers for astigmatism assessment

Poster Details

First Author: J.García-Pérez SPAIN

Co Author(s):    J. Gros-Otero   V. Blázquez-Sánchez   M. García-González   L. Álvarez-Rementería     

Abstract Details


Accurate assessment of corneal astigmatism plays a significant role in the refractive outcome of cataract surgery. Numerous methods have been developed to measure the shape of the anterior corneal surface. The VERION Image Guided System has been recently implemented to assist ophthalmic surgeons in several steps of cataract surgery. The 'VERION Reference Unit' includes a keratometer which measurements are used in further steps for the intraocular lens calculation. We tested the agreement of the keratometric data obtained with the VERION Reference Unit compared with those obtained with IOL Master, Oculyzer and Orbscan.


Clinica Rementeria. Private Eye Clinic, Madrid, Spain


A retrospective study was performed, including patients who had undergone cataract surgery without any other ocular disease. The preoperative measurements of the 'VERION Reference Unit' include a keratometric study, limbus and pupil postition and diameter, corneal reflex position and a still image of the eye. Keratometric data is used for the calculation of intraocular lens power. Patients enrolled were the first in which VERION was used. The measurements obtained where added to those of routine clinical practice that includes keratometric values obtained with IOL Master and Oculyzer or Orbscan.


Sixty eyes of forty-three patients with a mean age of 70,1 +/- 6,6 years were included. Mean astigmatism measured with VERION and IOL Master was -1,07±0,56 and -1,19±0,6 diopters respectively. The Intraclass Correlation Coefficient (ICC) for the flat meridian was 0,976 (p<0,0005) between VERION and IOL Master, 0,979 (p<0,0005) between VERION and Oculyzer, and 0,915 (p<0,0005) between VERION and Orbscan. The ICC for the steep meridian was 0,958 (p<0,0005) between VERION and IOL Master, 0,950 (p<0,0005) between VERION and Oculyzer and 0,910 (p<0,0005) between VERION and Orbscan. The ICC for the corneal axis was 0,802 (p<0,0005) between VERION and IOL Master, 0,591 (p<0,0005) between VERION and Oculyzer and 0,731 (p<0,0005) between VERION and Orbscan. Bland-Altman plots were calculated for the adequate interpretation of the ICC. The fall of agreement between methods when evaluating the corneal axis correlates with the 0-180º meridian.


The keratometric measurements showed a very high agreement when measured by VERION and the other keratometers studied. The agreement in the axis location was high between VERION and IOL Master, but moderate between VERION and Oculyzer and Orbscan. FINANCIAL INTEREST: NONE

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