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Sarah Elise Brown, Darby Miller, Ann Ostrovsky, Sylvan Wallenstein, Mark Speaker; Accuracy of Prediction of Steep Axis and Cylinder Power Using IOL Master versus Pentacam in Patients Undergoing Toric IOL Implantation. Invest. Ophthalmol. Vis. Sci. 2014;55(13):2142.
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© ARVO (1962-2015); The Authors (2016-present)
To compare predictive accuracy of corneal cylinder power and axis between IOL Master and optical zones of various size measured by the Pentacam corneal topographer in patients undergoing toric intraocular lens (IOL) implantation.
Pre- and post-operative keratometry measured by IOL Master and Pentacam in patients undergoing toric IOL implantation was retrospectively analyzed. Pearson correlation was used to determine the degree of agreement between keratometry measurements made by IOL master and Pentacam at 4 different optical zones: Sagittal (Sgl) 2.0 mm, 3.0 mm, 3.5mm, and 4.0 mm, and Total Refractive Power (TRP) 2.0 mm, 3.0mm, and 4mm. Predicted post-operative residual cylinder and axis values were determined. The agreement between predicted and actual post-operative residual cylinder values using the above keratographic methods was evaluated using a paired T-test. The percentages of eyes with postoperative residual cylinder at a steep axis within 20°, between 20° and 30°, and greater than 40° away from the predicted steep axis measured by the two devices were quantified.
31 eyes of 23 patients were analyzed. Agreement between steep keratometry values [K2] of the two devices was strong (r = 0.806 - 0.926; p<0.0001). Axis and total cylinder values demonstrated moderate and poor correlation, respectively, between the two devices (0.229 - 0.638 and 0.051 - 0.309, respectively). Of the 7 sets of Pentacam measurements, the best correlation with IOL master K2 and axis occurred with Pentacam Sgl 4.0 mm zone (r = 0.638 axis; r = 0.915 K2; p<.0001). The amount of residual post-operative cylinder (mean 0.398 ± 0.45) did not correlate well between the two instruments (p>0.5). Among all the sets of predicted postoperative axis values, the TRP 2.0 mm group projected the highest percentage within 20° of the actual postoperative axis.
The IOL Master and Pentacam offer similar preoperative keratometry measurements and both can be used to assist in choice of the correct power and orientation of a toric IOL. The ability to obtain keratometric data in optical zones of variable size as measured by the Pentacam might offer advantages in measuring the various topographic parameters when planning toric IOL implantation.
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