Repeatability of Measures of Corneal and Anterior Segment Scheimpflug-Based Tomography in Normal and Keratoconic Eyes

Santos, Rodrigo

Repeatability of Measures of Corneal and Anterior Segment Scheimpflug-Based Tomography in Normal and Keratoconic Eyes

Friday, April 25, 2014

KIOSKS (Boston Convention and Exhibition Center)

Rodrigo T. Santos, MD, Rio de Janeiro Corneal Tomograhyand Biomechanics Study Group, SAO JOSE DOS CAMPOS, Brazil

Isaac C. Ramos, MD, Hospital de Olhos Santa Luzia, Maceió-AL, Brazil

Rosane Correa, MD, Rio de Janeiro Corneal Tomography and Biomechanical Study Group, Rio de Janeiro, Brazil

Bernardo T. Lopes, MD, Rio de Janeiro Corneal Tomography and Biomechanical Study Group, Rio de Janeiro, Brazil

Jorge Augusto Siqueira da Silva, MD Niteroi - Rio de Janeiro, Brazil

Bruno F. Valbon, MD, University of São Paulo, Niterói, Brazil

Renato Ambrósio Jr., MD, PhD, Inst. Olhos R. Ambrósio, Rio de Janeiro, Brazil

Narrative Responses:

Purpose
To analyze and compare the repeatability of various corneal tomography parameters from a corneal and anterior segment Scheimpflug-based tomography in normal and keratoconic eyes.

Methods
Patients treated at the Renato Ambrósio Institute (Rio de Janeiro, Brazil) were invited to participate and voluntarily accepted. We studied 10n eyes randomly selected from 10 patients with normal corneas and 10 eyes randomly selected from 10 patients with keratoconus. Each eye was examined five consecutive times with the Pentacam HR (Oculus, Wetzlar, Germany). The standard deviation (SD [index of repeatability]) was calculated for the main parameters.

Results
The repeatability of measurements on keratoconic eyes was statistically significantly higher than normal eyes respectively (Mann-Whitney U test, p < 0.05) for the parameters: flat curvature (K1) 0.13 and 0.07; steep curvature (K2) 0.17 and 0.10; astigmatism 0.22 and 0.11; maximum Ambrosio relational thickness (ART max) 12.84 and 29.36; average of relative pachymetric progression (RPI ave) 0.09 and 0.02; minimum relative pachymetric progression (RPI min) 0.12 and 0.05; maximum relative pachymetric progression (RPI max) 0.18 and 0.07; deviation of average pachymetric progression (BAD Dp) 0.62 and 0.14.

Conclusion
The tomographic measurements of among keratoconic eyes present higher variability than in normal eyes. Nowadays, tomographic data is used for evaluation of keratoconus diagnosis and progression. It’s important analysing the data very carefully and consider the repeatability of the device.