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Comparison of keratometry measurements using the P entacam HR , the O rbscan IIz, and the TMS ‐4 topographer
Author(s) -
Tajbakhsh Zahra,
Salouti Ramin,
Nowroozzadeh Mohammad H,
AghazadehAmiri Mohammad,
Tabatabaee Seyedmehdi,
Zamani Mohammad
Publication year - 2012
Publication title -
ophthalmic and physiological optics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.147
H-Index - 66
eISSN - 1475-1313
pISSN - 0275-5408
DOI - 10.1111/j.1475-1313.2012.00942.x
Subject(s) - keratometer , ophthalmology , astigmatism , corneal topography , mathematics , analysis of variance , repeated measures design , medicine , physics , optics , statistics , visual acuity
Purpose To compare and evaluate the agreement between keratometry readings using three devices: the P entacam HR , the O rbscan II z, and the TMS ‐4 topographer. Methods In this prospective comparative study, 115 eyes from 115 healthy refractive surgery candidates were sequentially examined using three devices. Fourier analysis was used to evaluate corneal astigmatism in these subjects. The outcome measures comprised steep and flat keratometry readings, corneal astigmatism, the mean keratometry reading, and the J0 and J45 components. Repeated‐measures analysis of variance ( RM‐anova ) and B land– A ltman plots with 95% limits of agreement were used to evaluate the difference between measurements. Results The mean keratometry readings were 43.89 ± 1.51, 43.52 ± 1.48, and 43.79 ± 1.50 D using the TMS ‐4 topographer, the Orbscan IIz, and the Pentacam HR, respectively ( p < 0.001; RM‐anova ). The mean keratometric astigmatism was 1.27 ± 0.87, 1.20 ± 0.86, and 1.21 ± 0.82 D using the TMS ‐4 topographer, the O rbscan II z, and the P entacam HR , respectively ( p = 0.007; RM‐anova ). The J0 measurements were higher using the TMS ‐4 topographer compared with the O rbscan II z ( p = 0.021; B onferroni test). The mean, steep, and flat keratometry data were in better agreement using the TMS ‐4 topographer and the P entacam HR . In general, the O rbscan II z device measured lower values than either the TMS ‐4 topographer or the P entacam HR . However, the corneal astigmatism measurements and the J0 component showed the best agreement using the TMS ‐4 topographer and the O rbscan II z. Conclusions The TMS ‐4 topographer and the P entacam HR produced similar readings and can be used interchangeably to measure simulated keratometry values in young, healthy eyes. To measure corneal astigmatism, the TMS ‐4 topographer and the O rbscan II z produced values that were similar and could be used interchangeably.