Gaussian Power with Cylinder Vector Field Representation for Corneal Topography Maps

Barsky, Brian A.; Klein, Stanley A.; Garcia, Daniel D.

doi:10.1097/00006324-199711000-00025

Cited by 25 publications

(20 citation statements)

References 8 publications

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“…the curvature of the curve obtained by the intersection of the optical surface with a plane that contains, for a point at the surface, the tangent along the radial direction and the normal. I note that, within the framework of corneal topography, Barsky called this curvature normal instantaneous curvature .…”

Section: Normal Meridional and Geodesic Curvaturesmentioning

confidence: 99%

“…The meridional curvature is the curvature of the curve obtaining by intersecting the optical surface with a meridional plane. Again, within the context of corneal topography, Barsky called this curvature meridional instantaneous curvature . The meridional planar curve is obtained using the radial coordinate as the curve parameter: r = t (being θ fixed).…”

Section: Normal Meridional and Geodesic Curvaturesmentioning

confidence: 99%

“…Among these proposals the most relevant ones to this work are those based on curvature measurements. The meridional curvature (from which is derived the so‐called meridional instantaneous power) is the most commonly used. It is simply the curvature of the curve obtained by intersecting the surface with a meridional plane.…”

Section: Introductionmentioning

confidence: 99%

“…However this curvature provides limited information. Consequently Barsky alternatively proposed to use Gaussian curvature which has the advantage that its value is independent of the axis. Other authors have proposed to use the mean curvature which is also independent of the axis.…”

Section: Introductionmentioning

confidence: 99%

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The concept of geodesic curvature applied to optical surfaces

Barbero

2015

Ophthalmic Physiologic Optic

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Purpose To propose geodesic curvature as a metric to characterise how an optical surface locally differs from axial symmetry. To derive equations to evaluate geodesic curvatures of arbitrary surfaces expressed in polar coordinates. Methods The concept of geodesic curvature is explained in detail as compared to other curvature‐based metrics. Starting with the formula representing a surface as function of polar coordinates, an equation for the geodesic curvature is obtained depending only on first and second radial and first order angular derivatives of the surface function. The potential of the geodesic curvature is illustrated using different surface tests. Results Geodesic curvature reveals local axial asymmetries more sharply than other types of curvatures such as normal curvatures. Conclusion Geodesic curvature maps could be used to characterise local axial asymmetries for relevant optometry applications such as corneal topography anomalies (keratoconus) or ophthalmic lens metrology.

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Section: Normal Meridional and Geodesic Curvaturesmentioning

confidence: 99%

Section: Normal Meridional and Geodesic Curvaturesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The concept of geodesic curvature applied to optical surfaces

Barbero

2015

Ophthalmic Physiologic Optic

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“…This is the only one of our four metrics that is not a function of the central axis or of the PFP; rather, it is purely a measure of the surface's refracting power. The advantage of this definition over other traditional representations such as mean sphere 13 , Gaussian power 14,15 , axial power, and instantaneous power is that this metric illustrates spherical aberration. Those other metrics would be constant for a sphere, whereas instantaneous refractive power increases away from the center.…”

Section: Instantaneous Refractive Powermentioning

confidence: 99%

CWhatUC: a visual acuity simulator

1998

Self Cite

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CWhatUC (pronounced "see what you see") is a computer software system which will predict a patient's visual acuity using several techniques based on fundamentals of geometric optics. The scientific visualizations we propose can be clustered into two classes: retinal representations and corneal representations; however, in this paper, we focus our discussion on corneal representations. It is important to note that, for each method listed below, we can illustrate the visual acuity with or without spectacle correction. Corneal representations are meant to reveal how well the cornea focuses parallel light onto the fovea of the eye by providing a pseudo-colored display of various error metrics. These error metrics could be: a) standard curvature representations, such as instantaneous or axial curvature, converted to refractive power maps by taking Snell's law into account b) the focusing distance from each refracted ray's average focus to the computed fovea c) the retinal distance on the retinal plane from each refracted ray to the chief ray (lateral spherical aberration)For each error metric, we show both real and simulated data, and illustrate how each representation contributes to the simulation of visual acuity.

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Corneal Topography and Wavefront Analysis

Gatinel

2022

Albert and Jakobiec's Principles and Practice of Ophthalmology

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Gaussian Power with Cylinder Vector Field Representation for Corneal Topography Maps

Cited by 25 publications

References 8 publications

The concept of geodesic curvature applied to optical surfaces

The concept of geodesic curvature applied to optical surfaces

CWhatUC: a visual acuity simulator

Corneal Topography and Wavefront Analysis

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