Corneal astigmatism analysis method for corneal topography diagnosis

An analysis method and technology of corneal topography, which are applied in the fields of diagnosis, eye testing equipment, medical science, etc., can solve the problems that are not suitable for quantitative evaluation of irregular astigmatism, and cannot provide axial information of corneal astigmatism distribution.

Active Publication Date: 2019-04-02
WENZHOU MEDICAL UNIV
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  • Abstract
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  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Clinical corneal topography can provide ophthalmologists with the distribution of corneal refractive power and the regular astigmatism of the cornea, but cannot provide the astigmatism distribution of the cornea and its corresponding axial information, and is not suitable for quantitative evaluation of irregular astigmatism

Method used

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  • Corneal astigmatism analysis method for corneal topography diagnosis
  • Corneal astigmatism analysis method for corneal topography diagnosis
  • Corneal astigmatism analysis method for corneal topography diagnosis

Examples

Experimental program
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Effect test

Embodiment 1

[0032] Calculation and analysis of corneal astigmatism in ordinary people:

[0033] (1) Collect the anterior segment biometric data of ordinary human eyes to obtain the full corneal height distribution, and obtain the pupil eccentricity from the coordinates of the corneal topographic positioning measurement center and the pupil measurement center;

[0034] (2) Define the maximum aperture circle radius including all effective measurement points of the cornea;

[0035] (3) Using the least squares method, Zernike polynomials were used to fit the height data of all corneal measurement points within the radius of the aperture circle, and the Zernike radial order was 20;

[0036] (4) Reconstruct the continuous and complete corneal surface shape according to the Zernike polynomial coefficients obtained by surface fitting (see figure 2 ), the sampling distance of the surface is 0.12mm*0.12mm;

[0037] (5) Solve the first-order and second-order partial derivative expressions of the ...

Embodiment 2

[0042] Calculation and analysis of corneal astigmatism after wearing orthokeratology lenses:

[0043] (1) Collect the biometric data of the anterior segment of the patient wearing orthokeratology lenses to obtain the full corneal height distribution, and obtain the pupil eccentricity from the coordinates of the corneal topographic positioning measurement center and the pupil measurement center;

[0044] (2) Define the maximum aperture circle radius including all effective measurement points of the cornea;

[0045] (3) Using the least squares method, Zernike polynomials were used to fit the height data of all corneal measurement points within the radius of the aperture circle, and the Zernike radial order was 20;

[0046] (4) According to the Zernike polynomial coefficients obtained by surface fitting, a continuous and complete corneal surface shape was reconstructed, and the sampling distance of the surface shape was 0.12mm*0.12mm;

[0047] (5) Solve the first-order and secon...

Embodiment 3

[0053] Calculation and analysis of astigmatism in untreated keratoconus:

[0054] (1) Select the keratoconus case, collect the anterior segment biometric data of the keratoconus case, obtain the whole corneal height distribution, and obtain the pupil eccentricity from the coordinates of the corneal topographic positioning measurement center and the pupil measurement center;

[0055] (2) Define the maximum aperture circle radius including all effective measurement points of the cornea;

[0056] (3) Using the least squares method, Zernike polynomials were used to fit the height data of all corneal measurement points within the radius of the aperture circle, and the Zernike radial order was 20;

[0057] (4) According to the Zernike polynomial coefficients obtained by surface fitting, a continuous and complete corneal surface shape was reconstructed, and the sampling distance of the surface shape was 0.12mm*0.12mm;

[0058] (5) Solve the first-order and second-order partial deriv...

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Abstract

Provided is a corneal astigmatism analysis method of corneal topography diagnosis. According to corneal discrete-point height data acquired by anterior-segment biological measurement equipment, higher-degree polynomials are adopted to fit the measured data and to accurately reconstruct a corneal surface contour, by solving first-order and second-order partial derivatives of the corneal surface, in combination with differential geometry principles, two principal curvatures and orthogonal directions of the two principal curvatures of each point on the cornea are calculated, the differences of the principal curvatures are converted into corneal refractive power differences and serve as the corneal astigmatism, and the directions of the principal curvatures represent axial directions of the corneal astigmatism. The corneal astigmatism analysis method is applicable to arbitrary and continuous corneal topography which includes the diseased or postoperative cornea, not only can the regular astigmatism of the whole cornea be calculated, but also irregular astigmatism of the local cornea can be quantitatively evaluated, and the corneal astigmatism analysis method is conductive to the clinical diagnosis of corneal diseases and the refraction evaluation of the treated cornea.

Description

Technical field: [0001] The invention relates to the technical field of corneal topography and optical properties, in particular to a corneal astigmatism analysis method for corneal topography diagnosis. Background technique: [0002] Refractive errors of the human eye include myopia, hyperopia and astigmatism, among which astigmatism is divided into regular astigmatism and irregular astigmatism according to whether the maximum and minimum curvature meridians of the corneal principal meridian are orthogonal. The refractive power of the cornea accounts for about 70% of the refractive system of the whole eye, and the refractive power of the cornea mainly depends on the front surface of the cornea. Corneal disease or corneal refractive surgery may cause changes in corneal morphology, causing local irregular astigmatism in the lesion or surgical area, which will seriously affect visual quality. Therefore, ophthalmologists need to use the corneal topography data detected by ante...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): A61B3/107
CPCA61B3/107
Inventor 陈娇洁厉以宇冯海华陈思韵姜珺陈浩
Owner WENZHOU MEDICAL UNIV
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