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J.J. Rozema, D.E. van Dyck, F.J. Van de Velde, M. Tassignon; Laminographical Phase Reconstruction of the Anterior Segment of the Human Eye using Off-axis Wave-front Data . Invest. Ophthalmol. Vis. Sci. 2003;44(13):4082.
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Purpose: To present a technique that visualizes the origin of certain types of off-axis ocular wave-front aberrations in three dimensions. This is applied both on an eye model as well as real aberration data. Methods: We calculated the off-axis aberrations of a Navarro wide-angle eye model with an eccentricity of 40 degrees. These aberrations were expressed in terms of Zernike polynomials and considered as phase projections of a three dimensional lens system. After the removal of the defocus term a refraction corrected laminographic filtered backprojection algorithm was used on these projections to obtain a layer per layer phase reconstruction of the anterior segment. Further this simulated data was compared with a laminographic reconstruction of the measured off-axis aberrations that have previously been published by Navarro et al. Results: In the reconstructions it was possible to distinguish the different anterior ocular structures within a diamond shaped region, the overlap zone of the different projections. The resolution is relatively low since the projections, described by Zernike polynomials, only correspond to low spatial frequencies. The reconstruction from the real data seemed to give slightly sharper images. This might be due to a specific combination of Zernike polynomials that improved the quality of the reconstruction. Looking a little deeper into this matter we found that mainly the reconstructions of the pure astigmatism and coma polynomials, that were the most abundant in the off-axis wave-front data, had strong similarities with the anterior structures. Conclusions: Using laminography it is possible to make a low-resolution reconstruction of the anterior segment. The main Zernike components of the off-axis wave-fronts are found to be responsible. In the future this technique can be improved by using higher resolution wave-front recording methods.
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