Validity of the keratometric index: Evaluation by the Pentacam rotating Scheimpflug camera

Ho, Jau Der; Tsai, Ching‐Yao; Tsai, Ray Jui-Fang; Kuo, Li-Lin; Tsai, I-Lun; Liou, Shiow‐Wen

doi:10.1016/j.jcrs.2007.09.033

Cited by 137 publications

(104 citation statements)

References 33 publications

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“…In the literature, the ratio of the radius of the anterior corneal curvature to the radius of the posterior corneal curvature (the AP ratio) ranged from 1.132 (the Gullstrand schematic eye model) to 1.235 in the data from Dubbelman et al 24 With the Pentacam, a normal distribution was observed for most of the corneal parameters, and 1.223 was measured at the central 4.0-mm corneal zone for the AP ratio. 22 Monatalbán et al 25 reported an AP ratio of 1.19 with the Pentacam, which is smaller than that for our data (1.217). They showed that a significant, positive correlation existed between the AP shape factor (defined as 1+asphericity) ratio and age, as between the curvatures of the anterior, posterior corneal surfaces and age at 4.5-and 8.0-mm corneal diameters.…”

Section: Discussioncontrasting

confidence: 82%

Evaluation of Posterior Astigmatism Measured With Scheimpflug Imaging

Németh

Berta

Lipécz

et al. 2014

Cornea

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Purpose: Our aim was to assess the corneal power, axis, and age dependence of the anterior and posterior corneal surfaces with Scheimpflug imaging.Methods: Patients older than 10 years without a history of ocular surgery, corneal diseases, contact lens wearing, or severe dry eye were enrolled. Data regarding the anterior and posterior cornea were analyzed by means of Scheimpflug imaging (Pentacam HR).Results: The median age was 46.8 years (range: 10.0-90.3), and involved 827 eyes of 827 patients. Posterior corneal astigmatism was a median of 20.30 diopters (D) and exceeded 0.50 D in 12.56%. The ratio of the anterior-to-posterior corneal radius was a median of 1.217 (range: 1.021-1.402). The correlation between this ratio and age was significant (r = 20.219; P , 0.001). The correlation between anterior and posterior corneal astigmatism and age was significant. At the anterior surface, the ratio of with-the-rule astigmatism was 80.0% for the age range 10 to 20, decreasing to 36.0% for those aged over 81 years, whereas the ratio of against-the-rule astigmatism increased from 7.1% to 44.0%. At the posterior surface, the ratio of with-the-rule astigmatism was 94.3% for the age range 10 to 20 years, decreasing to 84.0% for those aged over 81 years, whereas the ratio of against-the-rule astigmatism increased from 1.4% to 8.0%. Conclusions:The posterior cornea significantly influences corneal astigmatism. Its power value and orientation are much more stable with advancing age compared with anterior surface values.

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Section: Discussioncontrasting

confidence: 82%

Evaluation of Posterior Astigmatism Measured With Scheimpflug Imaging

Németh

Berta

Lipécz

et al. 2014

Cornea

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“…In peer-reviewed papers, the reported percentage of patients achieving an UDVA better than 20/40 after toric IOL implantation ranges from 70% to 100% (4,5,32,33) . Spectacle-independence for distance vision was reported by 60% to 85% of patients with unilateral toric IOL (3,6,31,34) and by 69% to 97% of patients with bilateral toric IOLs (7,8,35,36) . Reported percentages of patients with residual refractive astigmatism lower than 0.50 D range from 25% to 100% (9,10,37,38) .…”

Section: Clinical Outcomesmentioning

confidence: 98%

Surgical management of astigmatism with toric intraocular lenses

Ventura¹,

Wang²,

Weikert³

et al. 2014

Arquivos Brasileiros De Oftalmologia

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“…This feature is of particular interest in keratoconus, where the corneal thickness varies with a non-linear pattern from the center to the periphery of the cornea. The keratometric index is refined with elevation topographs (Ho et al, 2008). Moreover, where keratometers assume that keratometry derives from a constant corneal refractive power, elevation topographs measures the true power of the cornea (Eryildirim et al, 1994).…”

Section: Topography-based Keratometrymentioning

confidence: 99%