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2 Optica Applicata

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Influence of glistening and calcium deposits in artificial intraocular lenses on retinal image quality – numerical model

Geniusz M., Zajac M.

Optica Applicata

2017

Vol. 47, nr 3

341--350

In modern ophthalmology the natural eye lens is sometimes replaced with an artificial implant – intraocular lens which remains in the eye for a long time. This can lead to the formation of numerous microdefects occurring on the intraocular lens surface or inside its volume. The most common include calcium deposits or microvacuoles referred to as glistenings. The presence of those defects causes deterioration of retinal image thus lowering the quality of vision. The purpose of this research is to develop a numerical model of human eye with intraocular lens burden with defects useful to predict the impact of calcium deposits and glistenings on the retinal image quality. The calculations made in accordance with this model suggest that the quality of retinal image deteriorates when the density of defects increases, but the degree of image deterioration does not depend on the location of the defects and transmittance of individual particles. The main deterioration effect is observed for low spatial frequencies (< 12 cycles/deg) both in case of calcium deposits and glistenings while for the spatial frequency of 30 cycles/deg the changes in modulation transfer function are insignificant. The presence of microvacuoles in the intraocular lens influences the worsening of modulation transfer function parameters only for the diameter of microvacuoles greater than 10 μm.

A theoretical model of the human eye based on ultrasound and corneal data

Falhar M., Rehak J.

Optica Applicata

2009

Vol. 39, nr 1

195--210

The purpose of this study was to create a theoretical model of the eye based on a comparison of the real spherical equivalent of the eye and the calculated value of the axial refraction. The main contribution of this model is that it enables calculation of the equatorial plane of the lens for accurate assessment of the IOL position for a spherical eye model. The Gullstrand model of the eye was used as the source eye model and this was modified for the purposes of this study. The axial refraction of the final model of the eye was compared with the spherical equivalent. The accuracy of the developed model was statistically confirmed using statistic tests. Individual calculation of the axial refraction using it shows that IOL calculation is possible without any general statistical presumptions. It permits the calculation of variables with an accuracy accepted by inferential statistics. The accuracy of this theoretical eye model however, is limited by extreme values of variables - an extreme value provides a less accurate result.