Analysis of Refractive errors in the human eye using Shack Hartmann Aberrometry
نویسندگان
چکیده
The refractive errors of normal, healthy eyes were measured using an indigenously developed Shack Hartmann aberrometer. Measurement was made in both right and left eyes after dilation for a 6mm pupil size. Power vector method was used to represent the sphero cylindrical errors. Analysis was done for astigmatism with the rule, oblique astigmatism and defocus between the right and left eyes of the subjects, which showed a negative, positive and zero correlation respectively. No correlation could be detected for RMS values between right and left eyes, though Zernike between right and left showed bilateral symmetry in our subjects. It was found that with an increase of spherical aberration, defocus decreased slightly. The validity and repeatability of our Shack Hartmann aberrometry in measuring the refractive error was analyzed and repeatability coefficient was calculated. Optimal correction for greater retinal image quality has been discussed and far point vergence for detecting the point of maximum retinal image quality is suggested.
منابع مشابه
Comparison of sorting algorithms to increase the range of Hartmann-Shack aberrometry.
Recently many software-based approaches have been suggested for improving the range and accuracy of Hartmann-Shack aberrometry. We compare the performance of four representative algorithms, with a focus on aberrometry for the human eye. Algorithms vary in complexity from the simplistic traditional approach to iterative spline extrapolation based on prior spot measurements. Range is assessed for...
متن کاملPrinciples of Hartmann-Shack aberrometry.
RAY OPTICS DESCRIPTION Nearly 400 years ago, the celebrated Jesuit philosopher-astronomer, Christopher Scheiner, professor at the University of Ingolstadt, demonstrated the focusing ability of the human eye using a simple device known as the Scheiner Disk.1 Scheiner's experiments showed that if an optically imperfect eye views through an opaque disk perforated with two pinholes, a single distan...
متن کاملCause of monocular diplopia diagnosed by combining double-pass retinal image assessment and Hartmann-Shack aberrometry.
PURPOSE To report an advanced optical procedure developed for the diagnosis of a particular case of diplopia. METHODS This approach combined the quantification of the level of intraocular scattering by using an Objective Scatter Index provided by a double-pass instrument (Optical Quality Analysis System) with the analysis of higher order aberrations using a Hartmann-Shack wavefront sensor. ...
متن کاملClassification of Ophthalmologic Images Using an Ensemble of Classifiers
The human eye may present refractive errors as myopia, hypermetropia and astigmatism. This article presents the development of an Ensemble of Classifiers as part of a Refractive Errors Measurement System. The system analyses Hartmann-Shack images from human eyes in order to identify refractive errors, wich are associated to myopia, hypermetropia and astigmatism. The ensemble is composed by thre...
متن کاملEstimation of centroid positions with a matched-filter algorithm: relevance for aberrometry of the eye.
Most Shack-Hartmann based aberrometers use infrared light, for the comfort of the patients. A large amount of the light that is scattered from the retinal layers is recorded by the detector as background, from which it is not trivial to estimate the centroid of the Shack-Hartmann spot. For a centroiding algorithm, background light can lead to a systematic bias of the centroid positions towards ...
متن کامل