Purpose: To compare the anterior and posterior elevation measurements above the best-fit sphere (BFS) between the Galilei (dual-Scheimpflug) and Pentacam (single-Scheimpflug) systems in candidates for refractive surgery.
Setting: Poostchi Ophthalmology Research Center, Shiraz, Iran.
Methods: In this prospective study, both eyes of consecutive patients were examined with the 2 imaging systems. The anterior and posterior BFS and the central and maximum elevation measurements in each of 4 quadrants were compared between the dual-Scheimpflug system and the single-Scheimpflug system. Bland-Altman plots were used to evaluate the agreement in the measurements between the imaging systems.
Results: The study comprised 31 patients (62 eyes). The mean radius of the anterior BFS measurement was 7.72 mm +/- 0.21 (SD) with the dual-Scheimpflug system and 7.83 +/- 0.21 mm with the single-Scheimpflug system. The mean radius of the posterior BFS was 6.37 +/- 0.18 mm and 6.47 +/- 0.19 mm, respectively. On the anterior and posterior elevation maps, the single-Scheimpflug system led to statistically significantly higher measurements than the dual-Scheimpflug system in the central, inferior, and temporal elevations (P<.001). Bland-Altman plots showed more agreement between the systems in anterior elevation measurements than in posterior elevation measurements.
Conclusion: In refractive surgery candidates with healthy eyes, the elevation map measurements with the single-Scheimpflug system were significantly different from those with the dual-Scheimpflug system in most aspects and therefore may lead to misinterpretation of clinical data that could alter clinical decisions if the 2 imaging systems are considered interchangeable.