Univariate and bivariate polar value analysis of corneal astigmatism measurements obtained with 6 instruments.
OBJECTIVE
To compare the corneal astigmatism measurements from 6 instruments in preoperative assessment for toric intraocular lens (IOL) implantation.


METHODS
Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, South Korea.


METHODS
Prospective comparative observational study.


METHODS
This study included patients with cataract and more than 1.00 diopter (D) of corneal astigmatism. For preoperative evaluation of toric IOL implantation, the net astigmatism was evaluated using manual keratometry, autokeratometry, partial coherence interferometry (PCI) (IOLMaster), corneal topography/ray-tracing aberrometry (iTrace), scanning-slit topography (Orbscan), and Scheimpflug imaging (Pentacam). All net astigmatisms were converted to polar values. Using the astigmatism measurements from manual keratometry as a standard, Bland-Altman analysis, linear mixed-model, and bivariate graphic analysis were performed.


RESULTS
The study group comprised 257 eyes of 141 patients. Bland-Altman plots showed good agreement between manual keratometry and each instrument for polar values. There was no significant between-instrument difference in KP(90) and KP(135) in the linear mixed model analysis or in bivariate polar values in bivariate confidence ellipses.


CONCLUSIONS
The corneal astigmatism measurements from autokeratometry, PCI, corneal topography/ray-tracing aberrometry, scanning-slit topography, and Scheimpflug imaging were comparable to those from manual keratometry and can be used interchangeably with manual keratometry to measure corneal astigmatism.
Institute of Vision Research, Yonsei University College of Medicine, Seoul, South Korea.
Hun
H
Lee
Jae Lim
JL
Chung
Eung Kweon
EK
Kim
Bradford
B
Sgrignoli
Tae-im
TI
Kim
D057128:Aberrometry / Q000295:instrumentation; D000368:Aged; D000369:Aged, 80 and over; D001251:Astigmatism / Q000175:diagnosis*; D001699:Biometry / Q000379:methods; D003315:Cornea / Q000473:pathology*; D019781:Corneal Topography / Q000295:instrumentation; D003941:Diagnostic Techniques, Ophthalmological / Q000295:instrumentation*; D005260:Female; D006801:Humans; D007368:Interferometry / Q000295:instrumentation; D019654:Lens Implantation, Intraocular; D008297:Male; D008875:Middle Aged; D018918:Phacoemulsification; D010781:Photography / Q000295:instrumentation; D011446:Prospective Studies; D015203:Reproducibility of Results; D041623:Tomography, Optical Coherence / Q000295:instrumentation