Search results for "Strehl ratio"
showing 6 items of 16 documents
In vitro optical quality comparison of 2 trifocal intraocular lenses and 1 progressive multifocal intraocular lens.
2015
Purpose To evaluate the optical quality of 3 multifocal intraocular lenses (IOLs): the Mini Well Ready progressive multifocal aspheric IOL, the AT LISA trifocal diffractive IOL, and the Finevision full diffractive trifocal IOL. Setting University of Valencia, Valencia, Spain. Design Experimental study. Methods An instrument designed for measuring real-time modulation transfer function (MTF) and IOL power was used to measure the optical quality of each IOL for 3.0 mm and 4.5 mm apertures. This instrument measures both sagittal and tangential MTFs. The optical quality of each IOL was evaluated with the MTF, through-focus MTF, defocus tolerance, Strehl ratio MTF, and relative percentage of lig…
Strehl ratio versus defocus for noncentrally obscured pupils.
1994
We discuss from the viewpoint of the Strehl ratio versus defocus, or the normalized axial-irradiance distribution, the influence of decentering the dark mask of an annular pupil. Our treatment, which is valid for pupil apertures with any Fresnel number, permits us to infer that the axial behavior of a noncentrally obscured pupil is equivalent to that of an apodizer with continuous amplitude variations. Hence the Strehl ratio versus defocus of an optical system can be shaped by use of noncentered dark masks that act as continuous gray apodizers. Several numerically evaluated examples are presented.
Clinical use of the ocular point spread function for retinal image quality assessment
2008
The purpose of this study is to demonstrate the clinical use of the point spread function (PSF) as metric for the assessment of retinal image quality in eyes with different ocular conditions. The PSF was computed from the wavefront aberrations obtained in seven eyes with different ocular conditions: emmetropia, myopia, hyperopia, post-myopic laser in situ keratomileusis (LASIK), post-hyperopic LASIK, keratoconus, Intacs ® in keratoconus, radial keratotomy (RK), LASIK after RK, cataract, phacoemulsification after cataract surgery, and LASIK after astigmatic keratotomy. The Strehl intensity ratio was calculated for all the PSFs computed. The PSF was correlated with the change in the optical e…
Optical quality comparison between 2 collagen copolymer posterior chamber phakic intraocular lens designs
2014
Purpose To compare the optical quality in vitro of 2 designs of the Visian Implantable Collamer Lens phakic intraocular lens (pIOL) for different powers and optical apertures. Setting University of Valencia, Valencia, Spain. Design Experimental study. Methods The Nimo TR1504 deflectometry device was used to measure the V4c pIOL, which has a smaller optic diameter, and the V5 pIOL, which has a larger optic diameter. The pIOLs were measured for −3.00 diopters (D), −6.00 D, −9.50 D, and −10.50 D at different optical apertures from 3.00 to 6.00 mm depending on the IOL power and model. The root mean square of higher-order aberrations (RMS HOAs) was analyzed. The Strehl ratio, point-spread functi…
Tolerance to rotation of toric monofocal and bifocal intraocular lenses. A theoretical study
2018
Abstract This manuscript aims to evaluate the tolerance to rotation of a toric monofocal and a toric bifocal intraocular lenses with different cylinder powers. Theoretical designs based on wavefront aberrations were created to simulate a toric monofocal and a toric bifocal intraocular lens. Cylinder power ranged from −1 D to −6 D, in steps of −1 D. Tolerance to rotation was estimated by the visual Strehl ratio based on the optical transfer function (VSOTF) metric. Tolerance to rotation for both monofocal and bifocal intraocular lenses decreased when the cylinder power increased. For the bifocal design studied, the tolerance to rotation was larger for the near focus than for the far, however…
Modulation transfer function in refractive-diffractive multifocal intraocular lenses in vitro
2007
Purpose: The optical quality of two types of multifocal, hybrid refractive-diffractive, intraocular lenses (IOL) is analyzed in vitro. Following the EN-ISO international standard, the IOLs’ modulation transfer functions (MTF) are determined for both distance and near vision. The behaviour of these curves when the pupil size varies is studied. Methods: The IOLs analyzed were: AcrySoft ResTor SN60D3 (Alcon) and Tecnis ZM900 (AMO). The MTF was calculated from the cross line-spread function recorded with the OPAL Vector System (Image Science Ltd. Oxford) by using fast Fourier transform techniques. The artificial eye model used simulates in vivo conditions of the anterior chamber including an ar…