Search results for "Spherical aberration"
showing 10 items of 48 documents
Lack of effect of intraocular lens asphericity on visual performance with acrylic intraocular lenses.
2011
Purpose. To determine whether implantation of acrylic intraocular lens (IOL) with aspheric design (Tecnis Z9003, AMO) results in improved visual acuity or contrast sensitivity compared with conventional spherical acrylic IOL (AR40e, AMO). Methods. In an intraindividual randomized prospective study of 60 patients with bilateral cataract, the Tecnis Z9003 IOL was compared with the AR40e IOL. Ocular aberrations for a 4.0-mm pupil and 6.0-mm pupil were measured with a Hartmann-Shack aberrometer. Quality of vision was measured using visual acuity and contrast sensitivity under mesopic and photopic conditions. Results. Eyes with the Tecnis Z9003 IOL had significantly less spherical aberration and…
Effect of partial and full correction of corneal spherical aberration on visual acuity and contrast sensitivity
2008
A 60-year-old white man had cataract surgery with an AcrySof IQ intraocular lens (IOL) implanted in the right eye and a Tecnis IOL implanted in the left eye. The ocular spherical aberration (SA) target for a 6.0 mm pupil was +0.10 microm for the right eye and 0 microm for the left eye. After surgery, the ocular SA in the right eye was significantly higher than that in the left eye (+0.112 microm +/- 0.002 [SD] versus +0.021 +/- 0.003 microm; P.001). No between-eye difference in the best corrected visual acuity and photopic contrast sensitivity was found. The contrast sensitivity was significantly better in the eye with the AcrySof IQ IOL at 12 and 18 cpd under mesopic conditions. The best c…
Reduction of the spherical aberration effect in high-numerical-aperture optical scanning instruments.
2006
In modern high-numerical-aperture (NA) optical scanning instruments, such as scanning microscopes, optical data storage systems, or laser trapping technology, the beam emerging from the high-NA objective focuses deeply through an interface between two media of different refractive index. Such a refractive index mismatch introduces an important amount of spherical aberration, which increases dynamically when scanning at increasing depths. This effect strongly degrades the instrument performance. Although in the past few years many different techniques have been reported to reduce the spherical aberration effect, no optimum solution has been found. Here we concentrate on a technique whose mai…
Metamaterial coatings for subwavelength-resolution imaging
2011
Coating lenses are membranes made of materials exhibiting negative index of refraction and deposited on other media with high dielectric constant e 3 . Unfortunately far-field imaging suffers from centrosymmetric aberrations. We propose a simple procedure to compensate partially deviations from ray-tracing perfect imaging in asymmetric metamaterial lenses. We also show that, under some circumstances, coating superlens may recover subwavelength information transmitted in a relative spatial spectrum ranging from 1 to √e 3 .
Reduction of spherical-aberration impact in microscopy by wavefront coding
2009
In modern high-NA optical scanning instruments, like scanning microscopes, the refractive-index mismatch between the sample and the immersion medium introduces a significant amount of spherical aberration when imaging deep inside the specimen, spreading out the impulse response. Since such aberration depends on the focalization depth, it is not possible to achieve a static global compensation for the whole 3D sample in scanning microscopy. Therefore a depth-variant impulse response is generated. Consequently, the design of pupil elements that increase the tolerance to this aberration is of great interest. In this paper we report a hybrid technique that provides a focal spot that remains alm…
Accommodation-related changes in monochromatic aberrations of the human eye as a function of age.
2008
PURPOSE. To investigate the relationship between accommodation and the optical aberrations of the whole human eye, as a function of age. METHODS. Sixty healthy subjects with spherical ametropia in the range 3 D, astigmatism less than 1 D, corrected visual acuity of 20/18 or better, and normal findings in an ophthalmic examination were enrolled. Subjects were divided into four groups, with age ranges of 19 to 29, 30 to 39, 40 to 49, and 50 to 60 years. Monochromatic optical aberrations and pupil size were measured with a Hartmann-Shack wavefront sensor under monocular viewing conditions, without pharmacological dilation or cycloplegia. Stimulus vergences were in the range of 0 to 5 D, with a…
Changes in the objective amplitude of accommodation with pupil size.
2014
PURPOSE We evaluate the effect of pupil size on objectively measured amplitude of accommodation (AA). METHODS Pupil diameter and wavefront aberrometry were obtained in 15 eyes when stimulus swept across the range of clear vision in steps of 0.5 diopters. Wavefront refraction techniques were used to compute objective AA as the maximum refractive change. Measurements were obtained monocularly under low and high ambient room lighting conditions with a fixed luminance of the fixation target. Amplitude of accommodation computations were performed taking into account just paraxial rays (paraxial AA) or including the effects of the change of spherical aberration during accommodation (minRMS AA). R…
Optical Quality Comparison of Conventional and Hole-Visian Implantable Collamer Lens at Different Degrees of Decentering
2012
To compare the optical quality of implantable Collamer lens (ICL) with and without central hole (Hole ICL and conventional ICL) at different degrees of decentering.Experimental laboratory investigation.Wavefront aberrations of the -3, -6, and -12 diopter (D) V4b and -3, -6, and -12 D V4c ICLs were measured in 3 conditions-centered and decentered 0.3 and 0.6 mm-at 3-mm and 4.5-mm pupils. The root mean square of total higher order aberrations, trefoil, coma, tetrafoil, secondary astigmatism, and spherical aberration were evaluated. In addition, point spread function and simulated retinal images of ICLs were calculated from the wavefront aberrations for each ICL and all conditions of decenteri…
Analysis of the irradiance along different paths in the image space using the Wigner distribution function
1997
Abstract The intensity distribution along different paths in the image space of an optical system is described in a two-dimensional phase-space domain in terms of the Wigner distribution function. This approach is useful for an efficient analysis of the performance of optical imaging systems suffering from spherical aberration. The good performance of the method is shown in some numerical simulations.