July 2018
Volume 59, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2018
Repeatability of Scheimpflug imaging and anterior segment optical coherence tomography parameters in keratoconus is decreasing with increasing severity
Author Affiliations & Notes
  • Berthold Seitz
    Department of Ophthalmology, Saarland University Medical Center, Homburg/Saar, Germany
  • Berit Elzer
    Department of Ophthalmology, Saarland University Medical Center, Homburg/Saar, Germany
  • Corinna Spira-Eppig
    Department of Ophthalmology, Saarland University Medical Center, Homburg/Saar, Germany
  • Achim Langenbucher
    Experimental Ophthalmology, Saarland University, Homburg/Saar, Germany
  • Elena Zemova
    Department of Ophthalmology, Saarland University Medical Center, Homburg/Saar, Germany
  • Nóra Szentmáry
    Department of Ophthalmology, Saarland University Medical Center, Homburg/Saar, Germany
    Department of Ophthalmology, Semmelweis University, Budapest, Hungary
  • Timo Eppig
    Experimental Ophthalmology, Saarland University, Homburg/Saar, Germany
  • Footnotes
    Commercial Relationships   Berthold Seitz, None; Berit Elzer, None; Corinna Spira-Eppig, None; Achim Langenbucher, None; Elena Zemova, None; Nóra Szentmáry, None; Timo Eppig, None
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science July 2018, Vol.59, 3436. doi:
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      Berthold Seitz, Berit Elzer, Corinna Spira-Eppig, Achim Langenbucher, Elena Zemova, Nóra Szentmáry, Timo Eppig; Repeatability of Scheimpflug imaging and anterior segment optical coherence tomography parameters in keratoconus is decreasing with increasing severity. Invest. Ophthalmol. Vis. Sci. 2018;59(9):3436.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : The indication for corneal crosslinking in keratoconus (KC) is typically based on the progression of tomographic parameters. Definition of progression, however, requires knowledge about measurement repeatability. The purpose of this study was to assess the repeatability of tomographic parameters in keratoconus depending on KC severity comparing two different devices.

Methods : A total of 129 eyes with keratoconus stages from 0 (normal) to 4 according TKC (Topographic Keratoconus Classification) were examined five times repeatedly with the Scheimpflug tomographer Pentacam HR (Oculus Optikgeräte GmbH, Wetzlar, Germany) and the anterior segment optical coherence tomographer (AS-OCT) Casia 2 (Tomey Corp., Nagoya, Japan). Main outcome measures included (1) mean anterior (KA) and (2) mean posterior power (KP), (3) mean astigmatism (KAST) and (4) corneal thickness at thinnest point (TCT). Results were compared between severity stages of KC, and in the same stage between two devices using Wilcoxon’s test. P-values <0.05 were considered statistically significant. In addition, the standard deviation (SD) of repeated measurements was compared between severity stages and within the severity stages between two devices.

Results : The number of eyes in TKC groups 0|1|2|3|4 was 25|20|24|27|33, respectively. TCT was measured significantly thicker (from 10 µm with TKC 0 to 28 µm with TKC 4) with the Pentacam HR. The SD of repeated measurements of KA, KP, KAST and TCT increased from (AS-OCT | Pentacam) 0.11 D | 0.08 D, 0.01 D | 0.03 D, 0.14 D | 0.09 D and 1 µm | 5 µm for eyes with TKC 0 to 0.98 D | 0.73 D, 0.12 D | 0.19 D, 1.00 D | 1.03 D and 11 µm | 12 µm for eyes with TKC 4. There were significant differences regarding keratometric and pachymetric data between the two devices for eyes with the same KC stage.

Conclusions : Repeatability of tomographic indices in keratoconus is decreasing with increasing severity of KC using Pentacam HR and AS-OCT Casia 2. None of the devices proofed to be consistenly more repeatable than the other. The tomographic results of both devices cannot be used interchangeably. Therefore, identification of KC progression should be performed with the same device. The magnitude of change for identifying progression should be adjusted according to the KC stage.

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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