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| Comparison of Scansys and Sirius Measurements of Anterior Segment Parameters in Patients with Myopia and Keratoconus |
| Hao Wu, Dingjuan Zhong, Jiao Chen, Dongqiang Luo, Guo Chen, Hua Wang |
| The First Affliated Hospital of Hunan Normal University, Hunan Provincial People's Hospital Optometry Center, Changsha 410000, China |
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Abstract Objective: To compare the consistency and differences in the measurement of ocular anterior segment parameters in patients with myopia and keratoconus using the domestic corneal topographer Scansys and the 3D ocular segment analyzer Sirius. Methods: This retrospective clinical study included 96 patients (96 eyes) with myopia and 61 patients (61 eyes) with keratoconus in the preoperative examination at the Optometry Center of Hunan Provincial People's Hospital from July 2021 to March 2022. Horizontal white- to-white (WTW), anterior chamber depth (ACD), fat axis of corneal curvature (Kf), steep axis of corneal curvature (Ks) and mean corneal curvature (Km), central corneal thickness (CCT), and thinnest corneal thickness (TCT) were measured using Scansys and Sirius, respectively. Paired t-test, Pearson correlation analysis, and Bland-Altman plot were used to detect the difference, correlation, and agreement in the results of two instruments. Results: Compared with Sirius, Scansys measured thicker CCT and TCT, smaller WTW, shallower ACD, and higher corneal curvature (Kf, Ks, Km) in both patient groups, with statistically signifcant differences (tCCT=10.42, 7.90, all P<0.001; tTCT=9.53, 5.60, all P<0.001; tWTW=-17.17, -8.42, all P<0.001; tACD=-12.93, -4.99, all P<0.001; tKf=5.20, 2.30, P<0.001, P=0.025; tKs=6.67, 4.47, all P<0.001; tKm=6.89, 2.97, P<0.001, P=0.004). Among myopic patients, the difference of WTW between the two instruments was (-0.45±0.26) mm. The correlation between the anterior segment parameters measured by the two instruments was positive (all r>0.78, P<0.001). The Bland-Altman agreement analysis showed that ACD and TCT of myopic and keratoconic patients measured by the two instruments had good consistency. The 95% limits of agreement (LoA) for ACD was -0.23-0.05 mm and -0.09-0.09 mm, respectively. The 95% LoA for TCT was -2.20-15.48 mm and -3.57-14.43 mm, respectively. The consistency of WTW measurement was poorer in myopic patients, with 95% LoAranging from -0.96 to 0.06 mm. Compared to myopic patients, in the corneal curvature (Kf, Ks, Km) measurements, the 95% LoAof patients in the keratoconic group was slightly wider and had slightly lower consistency for the two instruments. Conclusions: Scansys and Sirius have good correlation and consistency in measurements of ACD, TCT, Kf, Ks, and Km in patients with myopia and keratoconus, and the measurements can be substituted for each other. However, the consistency of WTW measurement in myopic patients was poor, and had clinically signifcant differences; the alternate use of these measurements was not recommended.
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Received: 06 February 2023
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| Fund:Hunan Provincial Education Department Project (22A0044) |
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Corresponding Authors:
Hua Wang, the First Affiliated Hospital of Hunan Normal University, Hunan Provincial People's Hospital Optometry Center, Changsha 410000, China (Email: WangHuaeye@163.com)
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