Objective To assess the agreement of keratometry and corneal astigmatism measurements by Orbscan II and Topolyzer. Methods In a prospective comparative study, 50 eyes of 50 healthy subjects were measured with the Orbscan II and Topolyzer. Data were analyzed using a paired sample t test and Bland-Altman plots. Results The mean differences of K1, K2, Km, J0 and J45 measured by Orbscan II and Topolyzer were -0.14±0.22 D, -0.18±0.29 D, -0.16±0.23 D, 0.03±0.12 D and -0.01±0.11 D, respectively. There were significant differences between the results of these 2 methods in K1 (t=-4.697, P<0.01), K2 (t=-4.516, P<0.01) and Km (t=-5.144, P< 0.01), but not for J0 (t=1.875, P>0.05) and J45 (t=-0.383, P>0.05). A Bland-Altman analysis showed that the results for the 2 devices were not comparable results for K1, K2 and Km (The largest 95% LoAs were 0.57 D, 0.75 D and 0.61 D, respectively.), but results were comparable for J0 and J45 (The largest 95% LoAs were 0.27 D and 0.22 D, respectively.). Conclusion The corneal astigmatism values obtained with Orbscan II were correlated very well with those of the Topolyzer. However, it is important to note in clinical practice that corneal power values acquired by these 2 devices are not directly interchangeable.
温岱宗,黄锦海,李学喜. Orbscan II与Topolyzer测量角膜曲率和散光参数的比较[J]. 中华眼视光学与视觉科学杂志, 2013, 15(5): 276-279.
WEN Dai-zong,HUANG Jin-hai,LI Xue-Xi. Comparison of Orbscan II and Topolyzer in the measurement of keratometry and corneal astigmatism. Chinese Journal of Optometry Ophthalmology and Visual Science, 2013, 15(5): 276-279. DOI: 10.3760/cma.j.issn.1674-845X.2013.05.005
Wang Q, Savini G, Hoffer KJ, et al. A comprehensive assessment of the precision and agreement of anterior corneal power measurements obtained using 8 different devices. PloS One,2012,7:e45607.
[4]
Douthwaite WA, Parkinson A. Precision of orbscan II assessment of anterior corneal curvature and asphericity. J Refract Surg,2009,25:435-443.
[5]
Thibos LN, Wheeler W, Horner D. Power vectors: an application of Fourier analysis to the description and statistical analysis of refractive error. Optom Vis Sci,1997,74:367-375.
[6]
Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet,1986,8:307-310.
[7]
Elbaz U, Barkana Y, Gerber Y, et al. Comparison of different techniques of anterior chamber depth and keratometric measurements. Am J Ophthalmol,2007,143:48-53.
[8]
González Pérez J, Cervino A, Giraldez MJ, et al. Accuracy and precision of EyeSys and Orbscan systems on calibrated spherical test surfaces. Eye Contact Lens,2004,30:74-78.
[9]
Karimian F, Feizi S, Doozandeh A, et al. Comparison of corneal tomography measurements using Galilei, Orbscan II, and Placido disk-based topographer systems. J Refract Surg,2011, 27:502-508.
[10]
Tajbakhsh Z, Salouti R, Nowroozzadeh MH, et al. Comparison of keratometry measurements using the Pentacam HR, the Orbscan IIz, and the TMS-4 topographer. Ophthalmic Physiol Opt,2012,32:539-546.
[11]
Eibschitz-Tsimhoni M, Tsimhoni O, Archer SM, et al. Effect of axial length and keratometry measurement error on intraocular lens implant power prediction formulas in pediatric patients. J AAPOS,2008,12:173-176.