Begoña Domenech

Repeatability and reproducibility of corneal thickness using SOCT Copernicus HR

The aim of this study is to determine the reliability of corneal thickness measurements derived from SOCT Copernicus HR (Fourier domain OCT).

Correlation between the dioptric power, astigmatism and surface shape of the anterior and posterior corneal surfaces

A knowledge of the shape of the cornea is of major importance for the planning and monitoring of surgery, and for the correct diagnosis of corneal diseases. Many authors have studied the geometry of the second corneal surface in the central region and it has been stated that there is a high correlation between the central radii of curvature and asphericities of the two corneal surfaces. In this work we extend this study to a larger, central, 6 mm diameter of the cornea. Surface height data, obtained with an Oculus Pentacam from 42 eyes of 21 subjects, were analysed to yield surface power vectors. Corneal heights of both surfaces were also decomposed into low‐order Zernike polynomials and the correlations between each of the power vectors and low‐order Zernike coefficients for the two surfaces were studied. There was not only a strong correlation between spherical powers and Zernike defocus coefficients, but also between the astigmatic components. The correspondence between the astigmatism in both surfaces found here can be of the utmost importance in planning optical surgery, since perfect spherical ablation of the first surface does not assure total correction of corneal astigmatism.

Focimeter measurement of the astigmatism arising from oblique central refraction

In this article, a method for measuring the astigmatism produced by an oblique central refraction is proposed. Measurements were taken using two different values of the pantoscopic angle that can be produced by lenses mourned in frames. We show that in sped lie cases, and as a function of the angle and power of the lens, the resulting astigmatism can surpass the tolerance level of the eye.