Assessment of Anterior, Posterior, and Total Central Corneal Astigmatism in Eyes With Keratoconus

Kamiya, Kazutaka; Shimizu, Kimiya; Igarashi, Akihito; Miyake, Toshiyuki

doi:10.1016/j.ajo.2015.08.016

Cited by 35 publications

(41 citation statements)

References 27 publications

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“…In this study, an increase relation between increasing astigmatism and higher-order aberrations, especially the asymmetry of coma aberration and trefoil aberration, was found, as well as a gradually decrease in ocular optical quality. Our results are in good agreement with previous studies relating ocular optical quality and corneal astigmatism [20–24], although there are few reports about the optical effect of increasing ocular astigmatism in children. In order to decrease the effect of high-order aberration on visual development, it is particularly important to correct the astigmatism of these children to avoid the negative effects of poor optical quality on their developing visual system.…”

Section: Discussionsupporting

confidence: 93%

The Effect of the Degree of Astigmatism on Optical Quality in Children

Gao

Wang

et al. 2017

Journal of Ophthalmology

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Purpose To investigate the effect of the degree of astigmatism on optical quality in children. The important objective evaluation parameters we focus on include the RMS of the high-order aberrations, MTF, and PSF. Methods The children, age ranging from 7 to 10 years old, underwent an optometry examination. Fifty-nine children who met the inclusion criteria were divided into three groups: A (1.0 D ≤ astigmatism < 2.0 D), B (2.0 D ≤ astigmatism < 3.0 D), and C (3.0 D ≤ astigmatism < 4.0 D). The OPD-SCAN-III aberrometer was used to measure PSF, MTF, and other optical parameters. Total higher-order aberrations, total coma aberrations, total spherical aberrations, and total trefoil aberrations corresponding to the RMS value, the AR value of MTF, and the SR value of PSF with a 4 mm pupil diameter were assessed. Results RMS-HO, RMS-T.Coma, RMS-T.Tre, and RMS-T.Sph in the three groups were significantly increased with increasing the degree of astigmatism, while there were no significant differences in RMS-T.Sph between the groups. The AR value and the SR value decreased with increasing degree of astigmatism, and there were significant differences in the AR value and the SR value. Conclusion Astigmatism has a significant influence on the higher-order aberrations, MTF, and PSF in the children. The effect of astigmatism value on the optical quality is mainly reflected in the change in these three parameters.

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Section: Discussionsupporting

confidence: 93%

The Effect of the Degree of Astigmatism on Optical Quality in Children

Gao

Wang

et al. 2017

Journal of Ophthalmology

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“…However, in eyes with ATR astigmatism of the anterior corneal surface, it increases total corneal astigmatism [15, 26]. Wacker et al showed that eyes with advanced FED were more likely than normal eyes to have oblique or WTR posterior corneal astigmatism [10].…”

Section: Discussionmentioning

confidence: 99%

“…For analysis of the relative orientations of corneal astigmatism, anterior corneal astigmatism, and total corneal astigmatism, these were classified as follows [13–15]: with-the-rule: 60° < the steep meridian < 120°against-the-rule: 0° < the steep meridian < 30° or 150° < the steep meridian < 180°oblique: otherwise.…”

Section: Methodsmentioning

confidence: 99%

Changes in Anterior, Posterior, and Total Corneal Astigmatism after Descemet Membrane Endothelial Keratoplasty

Alnawaiseh

Zumhagen

Rosentreter

et al. 2017

Journal of Ophthalmology

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Purpose. To evaluate changes in anterior, posterior, and total corneal astigmatism in patients after Descemet membrane endothelial keratoplasty (DMEK). Methods. We retrospectively included 29 eyes of 23 patients (age 67.6 ± 9.8 years, 13 female, 10 male) after DMEK surgery. The magnitude and axis orientation of anterior, posterior, and total corneal astigmatism before and after DMEK were determined using a rotating Scheimpflug system (Pentacam HR, Oculus). Results. The magnitude of anterior, posterior, and total corneal astigmatism in the central cornea did not change significantly after surgery. Before surgery, we found a significant correlation between the magnitudes of anterior and posterior corneal astigmatism (Spearman's correlation coefficient (rS) = 0.526, P = 0.003), while after surgery this correlation was no longer significant (rS = 0.038, P = 0.843). There was a significant correlation between the vector difference between preoperative and postoperative posterior astigmatism and the change in corneal pachymetry (rP = 0.47, P = 0.010). Conclusions. Posterior corneal astigmatism (especially the orientation) and therefore the relationship between anterior and total corneal astigmatism may change after DMEK. This should be considered to improve the accuracy of toric IOL power calculations following phakic DMEK or in combined procedures.

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“…In this regard, the present study set out the 3D characterization with patient-specific geometry of these KC cases in stages where a loss of visual function begins to occur. While the corneal refractive power is mostly determined by the anterior curvature [33], changes from the posterior surface are usually related to mild visual degradation [34]. The present report portrays the first study to assess the correlations of this geometrical method between the anterior and posterior corneal surfaces of keratoconic eyes with mild visual dysfunction.…”

Section: Discussionmentioning

confidence: 80%

Study of Morpho-Geometric Variables to Improve the Diagnosis in Keratoconus with Mild Visual Limitation

et al. 2018

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The validation of new methods for the diagnosis of incipient cases of Keratoconus (KC) with mild visual limitation is of great interest in the field of ophthalmology. During the asymmetric progression of the disease, the current diagnostic indexes do not record the geometric decompensation of the corneal curvature nor the variation of the spatial profile that occurs in singular points of the cornea. The purpose of this work is to determine the structural characterization of the asymmetry of the disease by using morpho-geometric parameters in KC eyes with mild visual limitation including using an analysis of a patient-specific virtual model with the aid of computer-aided design (CAD) tools. This comparative study included 80 eyes of patients classified as mild KC according to the degree of visual limitation and a control group of 122 eyes of normal patients. The metric with the highest area under the receiver operating characteristic (ROC) curve was the posterior apex deviation. The most prominent correlation was found between the anterior and posterior deviations of the thinnest point for the mild keratoconic cases. This new custom computational approach provides the clinician with a three-dimensional view of the corneal architecture when the visual loss starts to impair.

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Assessment of Anterior, Posterior, and Total Central Corneal Astigmatism in Eyes With Keratoconus

Cited by 35 publications

References 27 publications

The Effect of the Degree of Astigmatism on Optical Quality in Children

The Effect of the Degree of Astigmatism on Optical Quality in Children

Changes in Anterior, Posterior, and Total Corneal Astigmatism after Descemet Membrane Endothelial Keratoplasty

Study of Morpho-Geometric Variables to Improve the Diagnosis in Keratoconus with Mild Visual Limitation

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