Central and midperipheral corneal thickness measured with Scheimpflug imaging and optical coherence tomography.
OBJECTIVE
To compare corneal thickness measurements using Pentacam (Oculus, Germany), Sirius (CSO, Italy), Galilei (Ziemer, Switzerland), and RTVue-100 OCT (Optovue Inc., USA).


METHODS
Sixty-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.


RESULTS
Statistically significant differences (p<0.001) among the four devices were revealed in CCT, TCT and CT2mm measurements. 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.


CONCLUSIONS
The 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.
School of Optometry and Ophthalmology and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China; Key Laboratory of Vision Science, Ministry of Health P.R. China, Wenzhou, Zhejiang, China.
Jinhai
J
Huang
School of Optometry and Ophthalmology and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China; Key Laboratory of Vision Science, Ministry of Health P.R. China, Wenzhou, Zhejiang, China.
Xixia
X
Ding
School of Optometry and Ophthalmology and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China; Studio Oculistico d'Azeglio, Bologna, Italy.
Giacomo
G
Savini
Department of Ophthalmology, The Second Affiliated Hospital of Anhui Medical University, Hefei, Anhui, China.
Zhengxuan
Z
Jiang
School of Optometry and Ophthalmology and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China.
Chao
C
Pan
School of Optometry and Ophthalmology and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China.
Yanjun
Y
Hua
School of Optometry and Ophthalmology and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China.
Fan
F
Wu
School of Optometry and Ophthalmology and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China.
Yifan
Y
Feng
School of Optometry and Ophthalmology and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China.
Ye
Y
Yu
School of Optometry and Ophthalmology and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China; Key Laboratory of Vision Science, Ministry of Health P.R. China, Wenzhou, Zhejiang, China.
Qinmei
Q
Wang
D000328:Adult; D019573:Epithelium, Corneal / Q000166:cytology*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D011446:Prospective Studies; D041623:Tomography, Optical Coherence