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Comparison of Horizontal Corneal Diameter Measurements Using the Orbscan IIz and Pentacam HR Systems

Salouti, Ramin MD; Nowroozzadeh, Mohammad H. MD; Zamani, Mohammad MD; Ghoreyshi, Maryam MD; Khodaman, Amir R. MD

doi: 10.1097/ICO.0b013e3182a40786
Clinical Science

Purpose: To compare 2 automated devices for measuring the horizontal corneal diameter [white-to-white (WTW) distance].

Methods: In this prospective comparative case series, the WTW distance was measured by independent examiners using the Pentacam HR and the Orbscan IIz in 101 eyes of 101 healthy refractive surgery candidates. Statistical evaluation was performed using the paired t test, Pearson correlation, and the Bland–Altman method for comparison of measurement techniques.

Results: The mean WTW distance measurements were 11.76 ± 0.38 mm as obtained with the Pentacam HR and 11.66 ± 0.37 mm as obtained with the Orbscan IIz (P < 0.001). The measurements were highly correlated (Pearson correlation coefficient = 0.948; P < 0.001). The 95% limits of agreement for the Pentacam HR versus the Orbscan IIz were −0.14 to 0.33 mm.

Conclusions: The observed differences in WTW distance readings between the Pentacam HR and the Orbscan IIz are not clinically relevant, and the 2 devices could be used interchangeably in clinical practice.

*Poostchi Ophthalmology Research Center, Department of Ophthalmology, Shiraz University of Medical Sciences, Shiraz, Iran;

Salouti Eye Research Center, Salouti Private Eye Clinic, Shiraz, Iran; and

Department of Ophthalmology, Fasa University of Medical Sciences, Fasa, Iran.

Reprints: Maryam Ghoreyshi, Salouti Eye Research Center, Salouti Private Eye Clinic, Shiraz, Iran (e-mail:

The authors have no funding or conflicts of interest to disclose.

Received April 04, 2013

Accepted July 03, 2013

Copyright © 2013 Wolters Kluwer Health, Inc. All rights reserved.