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Vienna 2018 Delegate Registration Programme Exhibition Virtual Exhibition Satellites 2018 Survey


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Comparing surgically-induced astigmatism calculated by means of simulated keratometry vs total corneal refractive power

Poster Details

First Author: N.Garzón SPAIN

Co Author(s):    M. Rodri­guez-Vallejo   D. Carmona   J. Calvo-Sanz   F. Poyales   C. Palomino   J. Fernandez     

Abstract Details


To evaluate surgically-induced astigmatism (SIA) as computed by means of either simulated keratometry (KSIM) or total corneal refractive power (TCRP) after temporal incisions.


IOA Madrid Innova Ocular, Madrid, Spain


Prospective observational study including 36 right eyes undergoing cataract surgery. Astigmatism was measured preoperatively and during the three month follow-up period using Pentacam. SIA was computed considering anterior corneal surface astigmatism at 3 mm with KSIM and considering both corneal surfaces with TCRP from 1 mm to 8 mm (TCRP3for 3 mm). The eyes under study were divided into two balanced groups: LOW with KSIM astigmatism < 0.90 D and HIGH with KSIM astigmatism ≥ 0.90 D. Resulting SIA values were compared across groups and measuring techniques by means of vector analysis decomposition in orthogonal components.


Mean SIA was higher in the HIGH group (0.31 D @102º) than in the LOW group (0.04 D @16º). The temporal incision resulted in an increase of WTR SIA in the HIGH group of 0.15 D, as estimated with KSIM, vs. 0.28 D with TCRP3, but no significant increases were found for the SIAx in the LOW group or for the SIAy in either group. Differences between KSIM- and TCRP3-based SIA values were negligible in LOW group.


SIA was considerably higher in the high-astigmatism group and its value was underestimated with the KSIM approach. Eyes having low astigmatism should not be included for computing the SIA because induced WTR would be underestimated; posterior cornea astigmatism should be considered instead.

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