Comparability and repeatability of pachymetry in keratoconus using four noncontact techniques.
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Date
2015-09
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Abstract
Purpose: To compare and determine the repeatability of central corneal thickness (CCT) measurements
using four noncontact pachymetry instruments in eyes with keratoconus. Materials and Methods: The CCT
of consecutive patients with keratoconus was measured during a single visit using the swept source optical
coherence tomography (SS‑OCT, Casia SS‑1000°CT, Tomey, Nagoya, Japan), a rotating Scheimpflug camera
system (Pentacam, Oculus Optikgerate GmbH, Wetzlar, Germany), scanning slit topographer (Orbscan
IIz topography, Baush and Lomb Surgical Inc., San Dimas, CA, USA), and a hand‑held spectral domain
OCT (HHSD‑OCT, Bioptigen Inc., Durham, North Carolina, USA). Test‑retest variability, correlation
between measurements and interdevice agreement were analyzed. Results: Fifty eyes of 25 participants
were analyzed in this study. All measurement methods correlated well with each other (r > 0.9, P < 0.001).
Mean ± standard deviation CCT measured by HHSD‑OCT, Orbscan IIz, SS‑OCT, and Pentacam was
462 ± 41 μm, 458 ± 41 μm, 454 ± 40 μm, and 447 ± 42 μm, respectively. While the HHSD‑OCT over‑estimated
the CCT (P < 0.001), there was a good correlation between the measurements obtained from the other three
devices. However, the numerical difference was high and this trend was seen in all the paired comparisons.
Conclusions: Though the measurements by different devices correlated well, the numerical agreement may
be inadequate for their interchangeable use in clinical practice.
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Keywords
Central corneal thickness, hand‑held spectral domain optical coherence tomography, ultrasound pachymetry
Citation
Kumar Mukesh, Shetty Rohit, Jayadev Chaitra, Dutta Debarun. Comparability and repeatability of pachymetry in keratoconus using four noncontact techniques. Indian Journal of Ophthalmology. 2015 Sept; 63(9): 722-727.