Posters

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

Purpose:

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

Setting:

IOA Madrid Innova Ocular, Madrid, Spain

Methods:

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.

Results:

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.

Conclusions:

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.

Financial Disclosure:

None