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Maria Henriquez, Luis Izquierdo, Carmen Maldonado, Laura Cañola, Michelle Cerrate, Marta G Hadid; Diagnostic ability to distinguish high astigmatism from ectatic cornea using 2 different Scheimpflug devices.. Invest. Ophthalmol. Vis. Sci. 2018;59(9):4761. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the diagnostic ability of two Scheimpflug devices in differentiating normal high astigmatism eyes from ectatic corneas.
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, Wetzlar, Germany) and Galilei Dual Scheimpflug System (Ziemer Ophthalmic System AG, Port, Switzerland), 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), 61.11% (143/255), 41.02% (96/255) were classified as subclinical keratoconus (false positive) according to the index of surface variance, index of high decentration, average pachymetric progression index and the Belin/Ambrosio enhanced ectasia total derivation value (BAD-D). On Galilei preoperative screening indices 81.53%(53/65), 100% (65/65), 90,76% (59/65), 15.38% (10/65) reported false positive subclinical keratoconus according to standard deviation of corneal power, center/surround index, differential sector index, keratoconus prediction index.
The sensitivity of current subclinical keratoconus indices showed lack of predictability when discriminating between subclinical keratoconus and normal high astigmatic eyes.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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