Central and Midperipheral Corneal Thickness Measured with Scheimpflug Imaging and Optical Coherence Tomography

Abstract

PurposeTo compare corneal thickness measurements using Pentacam (Oculus, Germany), Sirius (CSO, Italy), Galilei (Ziemer, Switzerland), and RTVue-100 OCT (Optovue Inc., USA).MethodsSixty-six eyes of 66 healthy volunteers were enrolled. Three consecutive measurements were performed with each device. The mean value of the three measurements was used for subsequent analysis. Central corneal thickness (CCT), thinnest corneal thickness (TCT), and midperipheral corneal thickness (MPCT; measured at superior, inferior, nasal, and temporal locations with a distance of 1 mm (CT2mm) or 2.5 mm (CT5mm) from the corneal apex) were analyzed. Differences and agreement between measurements were assessed using the repeated-measures analysis of variance (ANOVA) and Bland-Altman analyses, respectively.ResultsStatistically significant differences (p<0.001) among the four devices were revealed in CCT, TCT and CT2mmmeasurements. The CCT, TCT, and CT2mm values were ranked from the thickest to the thinnest as follows: Galilei>Sirius>Pentacam>RTVue OCT. For these measurements, agreement between measurements by Sirius and Pentacam was good, whereas Galilei overestimated and RTVue underestimated corneal thickness compared to Sirius and Pentacam. As regards CT5mm measurements, Pentacam provided the largest values, whereas RTVue OCT yielded the smallest values. Agreement of the CT5mm measurements was good between the Pentacam, Sirius, moderate between Galilei and the other two Scheimpflug systems, and poor between the RTVue OCT and the remaining devices.ConclusionsThe Pentacam and Sirius can be used interchangeably for CCT measurements, while the Galilei and RTVue systematically over- and underestimate CCT, respectively. The three Scheimpflug cameras, but not the RTVue, may be used interchangeably for MPCT measurements.

Central corneal thickness evaluation in healthy eyes with three different optical devices

“…This "two in one system" allows a fast and complete analysis of both the entire cornea and the anterior segment in one step. A pachymetry map is then reconstructed using the point-bypoint anterior and posterior corneal surface data [12][13][14][15][16][17][18].…”

“…In recent years, several optical devices have been developed to measure CCT such as Orbscan II (Bausch & Lomb, Rochester, NY, USA), Pentacam HR (Oculus Inc, Wetzlar, Germany), Sirius (CSO, Firenze, Italy), Galilei (Ziemer, Port, Switzerland) and Optical Coherence Tomography [7][8][9][10][11][12][13][14][15][16]. USP is a contact method, which requires corneal anesthesia and can cause corneal discomfort and infections.…”

“…They do not cause corneal discomfort and there is no risk of infections; furthermore, they are less operator-dependent. For those above reasons, the no-contact devices are becoming increasingly common in the clinical practice [6][7][8][9][10][11][12][13][14][15][16][17][18]. Several authors have started to investigate the reproducibility of corneal pachymetry of those different optical devices.…”

“…Several authors have started to investigate the reproducibility of corneal pachymetry of those different optical devices. The results comparing different devices have provided contrasting results [6][7][8][9][10][11][12][13][14][15][16][17][18]. This prospective study was undertaken to compare CCT measurements obtained with Orbscan II, Pentacam HR and Sirius in healthy eyes.…”

Overview of Influence Factors on Corneal Thickness Measurement

“…Principle: Pentacam anterior segment analysis and measurement system is a newly designed threedimensional system in recent years for anterior segment analysis and diagnosis, in which Scheimpflug optimal principle is applied for tomography of anterior segment, using the computer to acquire threedimensional image of anterior segment according to the measurement data collected, meanwhile it may acquire the front and back surface morphology of cornea as well as full corneal thickness (Huang et al, 2014) (this sentence is way too long, so breaking it into 3 will make the reviewer/reader more comfortable).…”