To investigate inter-device agreement between the Pentacam (Optikgerate GmbH, Wetzlar, Germany) and IOLMaster (Carl Zeiss Meditec, Jena, Germany) in measuring corneal power, cylinder, and axis of astigmatism.
Retrospective case series reviewing the status of eyes after toric IOL implantation to evaluate inter-device agreement in measuring corneal power, cylinder, and axis of astigmatism.
Forty-nine eyes from 41 patients were evaluated. Agreement for corneal power and cylinder were deemed good and moderate, with 95% limits of agreement of -1.02 to +1.13 and -1.37 to +1.09 diopters (D), respectively. Agreement for axis of astigmatism was only fair, with a mean absolute difference of 8.9 degrees (range: 0.3 to 37.7 degrees, standard deviation: 8.79 degrees). Thirty percent of eyes had a 10-degree or greater difference in axis measurements, and 13% of eyes had a 20-degree or greater difference in measurements. Analysis by multivariate logistic regression showed higher cylinder powers associated with discrepant corneal power measurements (odds ratio: 3.46, P = .02), and increasing age was associated with discrepant axis measurements (odds ratio: 1.09, P = .03). Overall, there was no significant difference in accuracy predicting postoperative spherical equivalent refraction.
Pentacam and IOLMaster agree well for corneal power but less so for cylinder and axis of astigmatism and thus cannot be used interchangeably.
[Show abstract][Hide abstract] ABSTRACT: To evaluate inter-device agreement between Placido topography (iTrace; Tracey Technologies, Houston, TX) and Scheimpflug tomography (Pentacam; Oculus Optikgeräte GmbH, Wetzlar, Germany) for measuring corneal power and cylinder and axis of astigmatism.
Observational case series of 54 eyes from 54 subjects with no ocular disease. Main outcome measures were corneal power, cylinder power, and axis of astigmatism and their agreement was assessed by Bland-Altman analysis.
For corneal power and corneal cylinder, 95% limits of agreement (LoA) were considered good (-0.38 to 0.45 diopters [D] and -0.49 to 0.27 D, respectively). In contrast, the 95% LoA for corneal astigmatism axis exceeded the clinically relevant margins (-14.8 to 13.5): 28 eyes (52%) had a greater than 5° difference, 10 eyes (19%) had a greater than 10° difference, and 4 eyes (7%) had a greater than 20° difference between instruments. This absolute difference was significantly correlated with average corneal cylinder (Spearman's r = -0.379, P = .005) but not with average corneal power. In eyes with corneal astigmatism 2 D or greater, the 95% LoA for axis were -8.7° to 6.7°, whereas in those with corneal astigmatism less than 1 D, the 95% LoA for axis were -19.1° to 16.6°.
Placido topography and Scheimpflug tomography show good agreement for corneal power and cylinder, but not for corneal astigmatism axis. These instruments could be used interchangeably only in eyes with corneal astigmatism of 2 D or greater. [J Refract Surg. 2014;30(1):49-53.].
Journal of refractive surgery (Thorofare, N.J.: 1995) 03/2014; 30(1):49-53. DOI:10.3928/1081597X-20131217-06 · 3.47 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Corneal astigmatism is a common refractive error observed in a significant percentage of cataract patients. Accurate measurements of the preexisting corneal astigmatism are essential in order to achieve the desired refractive outcome after toric intraocular lens (IOL) implantation. This article presents a comprehensive review of recent published literatures on methods for measuring preoperative corneal astigmatism for toric IOL implantation.
A variety of instruments has been introduced and used to measure the magnitude and meridian of corneal astigmatism during preoperative assessments of cataract patients. Instruments that consider both the anterior and posterior corneal surfaces as critical factors for measuring total corneal astigmatism are expected to provide better accuracy. Although these instruments facilitate improved evaluations of corneal astigmatism and have helped minimize postoperative residual astigmatism, a perfect method to analyze preoperative corneal astigmatism has not yet been established.
Perfect correction of astigmatism after toric IOL implantation by using accurate corneal astigmatism values is the goal of this surgical procedure. To achieve this, correct and precise measurements of corneal astigmatism to determine the magnitude and meridian should be obtained.
Current Opinion in Ophthalmology 11/2014; 26(1). DOI:10.1097/ICU.0000000000000119 · 2.50 Impact Factor
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