Comparability and repeatability of corneal astigmatism measurements using different measurement technologies

Visser, Nienke; Berendschot, Tos T. J. M.; Verbakel, Frenne; Brabander, John de; Nuijts, Rudy M.M.A.

doi:10.1016/j.jcrs.2012.05.036

Cited by 93 publications

(57 citation statements)

References 33 publications

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“…This is in accordance with the findings of Visser et al, 21 who found that astigmatism measurements of six different devices, including the Lenstar and Pentacam, yielded values that were not statistically significantly different. Statistically significantly lower values were measured only when measurements of the posterior corneal surface were included with the Pentacam's equivalent keratometry values.…”

Section: Discussionsupporting

confidence: 93%

Evaluation of Keratometry With a Novel Color-LED Corneal Topographer

Klijn¹,

Reus²,

Sicam³

2015

J Refract Surg

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good refractive outcome in cataract and refractive surgery relies on accurate and precise keratometry, particularly in procedures to correct astigmatism. Erroneous keratometric measurements may be a source of intraocular lens (IOL) power calculation errors, 1,2 which lead to postoperative refractive surprises. In addition, appropriate measurement of cylinder axis is important in toric IOL implantation because every degree of misalignment reduces the corrective effect. 3,4The manual Javal-Schiøtz keratometer, invented in the late 19th century, has largely given way to a variety of automated keratometers. These devices employ different techniques to provide automated analogues of traditional, manual keratometry readings. Commonly used keratometers are based on reflections of Placido rings, reflections of monochromatic lightemitting diodes (LEDs), Scheimpflug images, or a combination of these. Although of proven clinical value, topography based on Placido rings holds the disadvantage of neglecting skew rays, 5 which may lead to inaccuracies in measuring features of the cornea that are not rotationally symmetric (eg, corneal cylinder). [6][7][8] This may be solved by using a corneal reflection source that allows for point-to-point reconstruction.9,10 Simulations have shown that such a technique might be more accurate and precise than topography based on Placido rings. METHODS: Sixty-three eyes of 63 patients with virgin corneas underwent keratometry with color-LED corneal topography (Cassini; i-Optics, The Hague, The Netherlands) and with devices based on Placido ring reflections (Keratron; Optikon, Rome, Italy), monochromatic LED reflections (Lenstar; Haag-Streit, Koeniz, Switzerland), and Scheimpflug imaging (Pentacam; Oculus Optikgeräte, Wetzlar, Germany). Three repeated measurements were performed with each device. Comparability and repeatability of corneal power and cylinder measurements were assessed. The Bonferroni-corrected α-threshold for statistical significance was 0.016. RESULTS:Corneal power measurements with the Cassini topographer were not statistically significantly different from those with the Pentacam (P = .64). They were statistically significantly lower than those with the Keratron and Lenstar (P < .01), but the differences were of negligible clinical relevance. Cylinder measurements with the Cassini topographer were not statistically significantly different from those with any other device (P = .46). Repeatability of Cassini corneal power measurements was not statistically significantly different from that of the Keratron (P = .02), but was statistically significantly lower than that of the Lenstar and Pentacam (P < .001). Repeatability of Cassini cylinder measurements was statistically significantly higher than that of the Pentacam and Keratron (P < .001), but was not statistically significantly different from that of the Lenstar (P > .05). CONCLUSIONS:Corneal power and cylinder measurements with color-LED corneal topography yielded values that were comparable to those of other commonly used d...

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Section: Discussionsupporting

confidence: 93%

Evaluation of Keratometry With a Novel Color-LED Corneal Topographer

Klijn¹,

Reus²,

Sicam³

2015

J Refract Surg

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“…Previous studies have shown that manual keratometry, automated keratometry, simulated keratometry of Placido-based corneal topography, and simulated keratometry of Scheimpflug imaging provide similar values for anterior corneal curvature (28)(29)(30) , although significant disagreement in axis location has been reported (29) . Contrarily, anterior corneal astigmatism measurements differed significantly when comparing values derived from total corneal power and equivalent keratometry to that of automated, manual, and simulated keratometry (30,31) . These three later measurements are based only on the anterior corneal surface data, while the total corneal power and equivalent keratometry are based on the measurements of both the anterior and posterior corneal curvatures.…”

Section: Devicesmentioning

confidence: 99%

Surgical management of astigmatism with toric intraocular lenses

Ventura¹,

Wang²,

Weikert³

et al. 2014

Arquivos Brasileiros De Oftalmologia

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“…At present, several types of keratometers are used in clinical practice; however, astigmatism measurements can differ between keratometers. [7][8][9] Thus, different keratometers might select different toricities for a given IOL. A previous study 10 showed the effect that the use of different keratometers has on the choice of a toric IOL.…”

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confidence: 99%