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Comparative evaluation of IOLMaster anterior corneal power and the Pentacam net corneal power in their ability to accurately predict the selection of power and orientation of a Tecnis toric lens

Session Details

Session Title: Biometry

Session Date/Time: Tuesday 08/10/2013 | 08:00-10:30

Paper Time: 08:47

Venue: Elicium 2 (First Floor)

First Author: : D.Nixon CANADA

Co Author(s): :                  

Abstract Details


The purpose of this analysis was to test which instrument, the Pentacam or the IOL Master, provided a better corneal astigmatism estimation for cylinder IOL power selection when the Holladay 1 formula is used.


Private practice in Canada


Forty patients receiving Tecnis Toric IOLs from a single surgeon were randomly selected for inclusion, with the criterion that they had completed all the measurements included in the study. Preoperative corneal power at two principal meridians was measured using the IOL Master and Pentacam. With the Pentacam, both the anterior central corneal power at 2.4mm and total central power at 2.4mm were considered. Collected data was used in the Tecnis Toric calculator and the resultant IOL was selected and implanted based on the graphic print-out. Pre-operative corneal marking and surgical techniques were consistent in all the cases. Axial length, implanted IOL power, and postoperative refraction and keratometry at 6 months were collected and reviewed. Corneal cylinder and axis were calculated from postoperative refraction and implanted IOL power, once translated into the corneal plane, while using the Holladay 1 formula. This is the keratometry that would have yielded the measured postoperative refraction with the implanted IOL cylinder power at the reported orientation (real keratometry). The vectorial difference between real keratometry and keratometry measured by each instrument was calculated.


The early analysis shows that the keratometry provided by the IOL Master has the smallest difference from the real keratometry. The vectorial difference between the real keratometry and that measured with each instrument did not show any preferred orientation. No patient required IOL repositioning and all patients had a BCVA of 7/7.5 or better and an UCVA of 6/12- or better.


The IOL Master, using anterior corneal power measurements, provides the best prediction of the postoperative corneal astigmatism. Therefore, the use of the IOL Master’s keratometry may provide a better toric IOL power determination when the Holladay 1 formula is considered than either the anterior or total corneal keratometry provided by the Pentacam.

Financial Interest:

... receives consulting fees, retainer, or contract payments from a company producing, developing or supplying the product or procedure presented

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