Hesham Mohamed Gharieb1,2, Ihab Saad Othman3,4, Rania Serag Elkitkat5,6. 1. Department of Ophthalmology, Faculty of Medicine, Ain Shams University, Cairo, Egypt. 2. Research & Development Department at Eye World Hospital, Dokki, Giza, Egypt. 3. Department of Ophthalmology, Faculty of Medicine, Cairo University, Giza, Egypt. 4. Eye World Hospital, Dokki, Giza, Egypt. 5. Department of Ophthalmology, Faculty of Medicine, Ain Shams University, Cairo, Egypt; and. 6. Al Watani Eye Hospitals, Cairo, Egypt.
Abstract
PURPOSE: Many topography/tomography devices are available, and their interchangeable use is frequently questioned. This study aimed to compare the analogous indices of Orbscan 3 and Pentacam HR to detect whether the interchangeable use of the 2 devices is feasible. METHODS: This retrospective study was conducted at Eye World Hospital, Giza, Egypt. Displays of Orbscan 3 (Bausch & Lomb; Technolas Perfect Vision GmbH) and Pentacam HR (Oculus Optikegrate) for 660 healthy right eyes were explored for various analogous indices. Bland-Altman plots with 95% limits of agreement (LoA) were used for comparisons. RESULTS: The highest systematic error and lowest agreement existed in the front and back elevations from the best fit sphere (mean differences of 4.7 and 9.2 μm, respectively, and 95% LoA of -2.5 to 12.0 and -10.0 to 28.6, respectively). There was a relatively wide 95% LoA for each pachymetry at the corneal apex (-18 to 22 μm) and at the thinnest location (-22 to 22 μm), anterior chamber depth (-0.88 to 0.95 mm), flattest keratometry (-0.44 to 0.62 D), and steepest keratometry (-0.71 to 0.89 D). By contrast, the lowest systematic error and highest agreement existed for front and back best fit sphere radii of curvature (mean difference of 0.08 mm and 95% LoA of -0.08 to 0.24 and mean difference of 0.03 mm and 95% LoA of -0.17 to 0.23, respectively). CONCLUSIONS: This study negates the accuracy of the use of devices interchangeably regarding most parameters. Therefore, examinations with the 2 devices should not be regarded comparable.
PURPOSE: Many topography/tomography devices are available, and their interchangeable use is frequently questioned. This study aimed to compare the analogous indices of Orbscan 3 and Pentacam HR to detect whether the interchangeable use of the 2 devices is feasible. METHODS: This retrospective study was conducted at Eye World Hospital, Giza, Egypt. Displays of Orbscan 3 (Bausch & Lomb; Technolas Perfect Vision GmbH) and Pentacam HR (Oculus Optikegrate) for 660 healthy right eyes were explored for various analogous indices. Bland-Altman plots with 95% limits of agreement (LoA) were used for comparisons. RESULTS: The highest systematic error and lowest agreement existed in the front and back elevations from the best fit sphere (mean differences of 4.7 and 9.2 μm, respectively, and 95% LoA of -2.5 to 12.0 and -10.0 to 28.6, respectively). There was a relatively wide 95% LoA for each pachymetry at the corneal apex (-18 to 22 μm) and at the thinnest location (-22 to 22 μm), anterior chamber depth (-0.88 to 0.95 mm), flattest keratometry (-0.44 to 0.62 D), and steepest keratometry (-0.71 to 0.89 D). By contrast, the lowest systematic error and highest agreement existed for front and back best fit sphere radii of curvature (mean difference of 0.08 mm and 95% LoA of -0.08 to 0.24 and mean difference of 0.03 mm and 95% LoA of -0.17 to 0.23, respectively). CONCLUSIONS: This study negates the accuracy of the use of devices interchangeably regarding most parameters. Therefore, examinations with the 2 devices should not be regarded comparable.