Scheimpflug photography–based clinical characterization of the correlation of the corneal shape between the anterior and posterior corneal surfaces in the normal human eye

Montalbán, Raúl; Piñero, David P.; Javaloy, Jaime; Alió, Jorge L.

doi:10.1016/j.jcrs.2012.06.050

Cited by 37 publications

(34 citation statements)

References 27 publications

(30 reference statements)

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“…Conversely, we found no correlation with anterior corneal radius, anterior chamber depth, axial length, anterior corneal astigmatism, and total corneal astigmatism. Significant correlations with posterior corneal radius, horizontal corneal diameter, and central corneal thickness were consistent with the findings of previous reports 5. Regarding the corneal thickness, we estimated that a 100 μm increase in central corneal thickness or a 2.0-mm decrease in horizontal corneal diameter caused an increase of <0.02 in the AP ratio.…”

Section: Discussionsupporting

confidence: 92%

Impact of the anterior-posterior corneal radius ratio on intraocular lens power calculation errors

Asato

Kojima

Yamamoto

et al. 2018

OPTH

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PurposeTo evaluate the distribution of the anterior–posterior corneal radius ratio (AP ratio; anterior corneal radius/posterior corneal radius) in patients before cataract surgery, and investigate which parameters can affect this ratio. We also investigated the impact of the AP ratio on the intraocular lens (IOL) power calculation error in cataract surgery.MethodA total of 501 eyes of 501 consecutive patients who had no history of corneal diseases and had undergone cataract surgery were enrolled in this study. The patients’ AP ratio was measured before surgery using anterior segment optical coherence tomography; using these data, we evaluated the correlation between the AP ratio and various parameters that can affect the corneal radius. For subgroup analyses, we investigated the correlation between the AP ratio and IOL power calculation error in 181 eyes of 181 patients. Stepwise multiple regression analysis was performed with the IOL power calculation errors of the SRK/T, Haigis, Holladay 1, and Hoffer Q formulas as the dependent variables and various parameters that can affect the postoperative IOL power calculation error as the independent variables.ResultsThe mean AP ratio was 1.19±0.02, and it weakly correlated with corneal thickness, horizontal corneal diameter, and posterior corneal radius. The correlations between the AP ratio and IOL power calculation errors in the 4 calculation formulas were not statistically significant. Stepwise multiple regression analysis could not detect any significant parameters affecting this ratio.ConclusionThe AP ratio has no major influence on IOL power calculation error in patients with any history of corneal disease.

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Section: Discussionsupporting

confidence: 92%

Impact of the anterior-posterior corneal radius ratio on intraocular lens power calculation errors

Asato

Kojima

Yamamoto

et al. 2018

OPTH

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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: 91%

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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“…The inverse correlation between k ratio and pachymetry in keratoconus eyes contrasts with the positive correlation found in the normal healthy eyes. 12 Specifically, our research group recently found that thin normal corneas tended to have a steeper anterior corneal surface compared to the posterior corneal surface. Therefore, in keratoconus eyes, the presence of a thinner cornea seems to be in relation with changes in the posterior corneal curvature rather than in the anterior.…”

Section: Discussionmentioning

confidence: 98%

“…In contrast, no significant correlation has been found in previous studies between anterior and posterior corneal asphericity in the normal healthy corneas. 12,16 The altered biomechanical properties of the cornea and the susceptibility of the corneal tissue to the stress induced by the intraocular pressure seem to lead to a simultaneous localized steepening in both corneal surfaces, maintaining a correlation of the anterior and posterior geometric profiles. Future studies should evaluate if this level of correlation is different in incipient forms of keratoconus, being a potentially diagnostic tool for this ectatic corneal condition, and the relationship between this level of correlation and the strength of the biomechanical weakening of the cornea.…”

Section: Discussionmentioning

confidence: 99%

Correlation of Anterior and Posterior Corneal Shape in Keratoconus

Montalbán

Alió

Javaloy

et al. 2013

Cornea

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Scheimpflug photography–based clinical characterization of the correlation of the corneal shape between the anterior and posterior corneal surfaces in the normal human eye

Abstract: No author has a financial or proprietary interest in any material or method mentioned.

Cited by 37 publications

References 27 publications

Impact of the anterior-posterior corneal radius ratio on intraocular lens power calculation errors

Impact of the anterior-posterior corneal radius ratio on intraocular lens power calculation errors

Evaluation of Posterior Astigmatism Measured With Scheimpflug Imaging

Correlation of Anterior and Posterior Corneal Shape in Keratoconus

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