| ORIGINAL ARTICLE |
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| Year : 2015 | Volume
: 63
| Issue : 9 | Page : 722-727 |
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Comparability and repeatability of pachymetry in keratoconus using four noncontact techniques
Mukesh Kumar1, Rohit Shetty1, Chaitra Jayadev1, Debarun Dutta2
1 Department of Cornea and Refractive Surgery, Narayana Nethralaya Super Specialty Eye Hospital, Bengaluru, Karnataka, India
2 School of Optometry and Vision Science, The University of New Wales, Sydney, New South Wales, Australia
Correspondence Address:
Mukesh Kumar
Narayana Nethralaya, 121/C, Chord Road, 1st "R" Block, Rajaji Nagar, Bengaluru - 560 010, Karnataka
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/0301-4738.170987
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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 mm, 458 ± 41 mm, 454 ± 40 mm, and 447 ± 42 mm, 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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