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Diagnostic ability to distinguish high astigmatism from ectatic cornea using two different Scheimpflug devices

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Session Details

Session Title: Anterior Segment Imaging II

Session Date/Time: Tuesday 25/09/2018 | 08:00-10:30

Paper Time: 10:02

Venue: Room A4

First Author: : M.Henriquez PERU

Co Author(s): :    L. Izquierdo Jr   M. Hadid   L. Canola-Ramirez   M. Cerrate   C. Maldonado   J. Chauca     

Abstract Details


To evaluate the diagnostic ability of two Scheimpflug devices in differentiating normal high astigmatism eyes from ectatic corneas.


Instituto de Ojos Oftalmosalud- Research Department


Retrospective cross-sectional, comparison of diagnostic instrument accuracy study, including 255 eyes evaluated between January 2014 to November 2017 with astigmatism over 1.5 Diopters in the subjective refraction and anterior corneal astigmatism, with a minimum follows up of 12 months after LASIK. The best 10 preoperative keratoconus and subclinical keratoconus screening indices were evaluated using the Pentacam HR (Oculus GmBH) and Galilei Dual Scheimpflug System (Ziemer Ophthalmic System AG), cut off values provided by previous studies and company based parameters were used to discriminate between normal and keratoconus and between normal and subclinical keratoconus. Statistical analysis was performed using Stata 13.


No eye developed ectasia over a mean follow-up of 12 months. On Pentacam preoperative screening indices 23.62% (60/255), 34.25% (87/255) and 61.11% (143/255) were classified as subclinical keratoconus (false positive) according to the index of surface variance, index of high decentration and average pachymetric progression index. On Galilei preoperative screening indices 81.53%(53/65), 100% (65/65), 90,76% (59/65) and 15.38% (10/65) reported false positive subclinical keratoconus according to standard deviation of corneal power, center/surround index, differential sector index and keratoconus prediction index respectively.


The sensitivity of current subclinical keratoconus indices showed lack of predictability when discriminating between subclinical keratoconus and normal high astigmatic eyes.

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