this study aimed to assess changes in contrast sensitivity and aberrations in cases of myopia greater than 5.0 diopter (d) who had photorefractive keratectomy (prk). in this semi-experimental study, 20 eyes of ten patients were studied. inclusion criteria were at least 5.0 d of myopia, stable refraction in the past year, no history of refractive surgery, a minimum corneal thickness of 480 μm, a...

In this paper, the optimal Fresnel lenses are designed by Zemax software.The fundamental problem of the Fresnel lenses is the beam divergence, which wasresolved by decreeing the output stain diameter on the image plane. For this purpose,two types of radial and cylindrical Fresnel lenses are simulated with different groovesusing Global and Hammer optimization methods. The minimum output stain di...

PURPOSE To analyze internal spherical aberration in pseudophakic eyes that underwent aspheric intraocular lens (IOL) implantation, and to investigate the relationships between biometric data and the effectiveness of aspheric IOL implantation. METHODS This retrospective study included 40 eyes of 40 patients who underwent implantation of an IOL having a negative spherical aberration of -0.20 μm...

The in vivo spherical aberration of the lenses of 26 subjects was estimated from the measured total aberration of the eye and that predicted from the measured shape of the anterior corneal surface. Since it was only possible to estimate the aberration contribution from the posterior corneal surface, its value led to an uncertainty in the final aberration level of the lens. For all the subjects ...

The ideal location for an aberration corrector in an electron-optical column is at the place where the aberration is introduced. In practice, this of course typically cannot be achieved. The resultant separation between where an aberration is introduced and where it is removed produces combination aberrations for all aberrations of higher than first order. In the case of third-order aberration ...

PURPOSE To examine the effect of misalignment (decentration and tilt) of intraocular lenses (IOLs) on retinal image quality using a water-immersed model eye with corneal spherical aberration adjusted to the values found in normal human eyes (spherical aberration 0.25 μm; pupil diameter 6 mm). METHODS Three types of IOL holders were prepared. The first was without decentration or tilt, the sec...

The ideal location for an aberration corrector in an electron-optical column is exactly at the place where the aberration to be corrected is introduced. In practice, this of course cannot be achieved. The resultant separation between where an aberration is introduced and where it is removed produces combination aberrations for all aberrations of higher than first order. A case of particular imp...

purpose: to compare acrysof iq and akreos ao aspheric intraocular lenses (iols) in terms of spherical aberration and contrast sensitivity. methods: thirty-seven eyes of 37 patients undergoing phacoemulsification cataract surgery were randomized to implantation of acrysof iq or akreos ao iols. three months postoperatively, best-corrected visual acuity (bcva), spherical aberration (with 4 and 6 m...