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(Reference retrieved automatically from SciELO through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Measuring higher order optical aberrations of the human eye: techniques and applications

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Author(s):
L. Alberto V. Carvalho ; J.C. Castro ; L. Antonio V. Carvalho
Total Authors: 3
Document type: Journal article
Source: Brazilian Journal of Medical and Biological Research; v. 35, n. 11, p. 1395-1406, Nov. 2002.
Abstract

In the present paper we discuss the development of "wave-front", an instrument for determining the lower and higher optical aberrations of the human eye. We also discuss the advantages that such instrumentation and techniques might bring to the ophthalmology professional of the 21st century. By shining a small light spot on the retina of subjects and observing the light that is reflected back from within the eye, we are able to quantitatively determine the amount of lower order aberrations (astigmatism, myopia, hyperopia) and higher order aberrations (coma, spherical aberration, etc.). We have measured artificial eyes with calibrated ametropia ranging from +5 to -5 D, with and without 2 D astigmatism with axis at 45º and 90º. We used a device known as the Hartmann-Shack (HS) sensor, originally developed for measuring the optical aberrations of optical instruments and general refracting surfaces in astronomical telescopes. The HS sensor sends information to a computer software for decomposition of wave-front aberrations into a set of Zernike polynomials. These polynomials have special mathematical properties and are more suitable in this case than the traditional Seidel polynomials. We have demonstrated that this technique is more precise than conventional autorefraction, with a root mean square error (RMSE) of less than 0.1 µm for a 4-mm diameter pupil. In terms of dioptric power this represents an RMSE error of less than 0.04 D and 5º for the axis. This precision is sufficient for customized corneal ablations, among other applications. (AU)

FAPESP's process: 00/06810-4 - Development of equipment for the determination of ocular aberrations using wave-front measurements by way of the Harmann-Shack Technique
Grantee:Jarbas Caiado de Castro Neto
Support type: Research Grants - Innovative Research in Small Business - PIPE