Search results for "CONTRAST SENSITIVITY"
showing 10 items of 115 documents
Corneo-scleral contact lens in a piggyback system for keratoconus: A case report.
2017
Purpose: We describe a case of fitting a corneo-scleral contact lens with a multi-aspheric geometry design (MAGD CScL) on top of a daily silicone hydrogel lens (piggyback system) for keratoconus management. Methods: A 48-year-old man using soft toric contact lenses required an improvement in the unsatisfactory quality of his vision. He presented with bilateral asymmetric keratoconus with high myopia in the right eye (RE) and severe myopia in the left eye (LE). In addition, he had low vision in his LE because of a maculopathy. He was fitted with MAGD CScL to correct his irregular astigmatism. A diagnostic trial set was used in the fitting process and the patient was assessed according to a s…
Contrast sensitivity of the visual system in speckle imagery
1994
The contrast sensitivity function (CSF) of the whole visual system is determined with the use of coherent diffuse illumination. This function provides supplementary data about the effect of speckle on the ability of the visual system to perceive the spatial information contained in an image. The results show that speckle not only prevents perception of the finest details (highest frequencies) but also reduces the visibility of lower frequencies (especially where contrast is low). The difference between the CSF's determined with and without speckle is quantitatively very important. And the ratio between the two CSF's is a measure of the retinal ability to perceive contrast in the presence of…
Influence of the contrast sensitivity function on the reaction time
1993
The reaction time (RT) vs spatial frequency (SF) curve is determined, using gratings from 1 to 40 c/deg, at seven different contrast levels between 0.95 and 0.02. The form of the RT/SF function: (a) replicated the inverse of the contrast sensitivity function (CSF) at near threshold contrast levels; (b) behaved differently at higher contrasts, exhibiting two branches at contrast close to 1. The interpretation is that there are two factors determining this function: (1) the transition from the operation of fast transient channels at low SF to the operation of slow sustained channels at high SF, the transition taking place within a narrow SF band close to 6 or 8 c/deg (depending on the subject…
Working-Age Cataract Patients: Visual Results, Reading Performance, and Quality of Life with Three Diffractive Multifocal Intraocular Lenses
2013
Purpose To compare the visual outcomes, reading performance, and quality of life (QoL) of working-age cataractous patients bilaterally implanted with 3 different diffractive multifocal intraocular lenses (MIOLs). Design Two-center, randomized, prospective, double-masked study. Participants Sixty-three consecutive patients (126 eyes) seen at Ophthalmology Section, Palermo and Florence University, Italy, randomized to receive the ReSTOR SN6AD3 (Alcon Laboratories, Inc, Irvine, CA) (20 patients, group A), ReSTOR SN6AD1 (Alcon Laboratories, Inc) (21 patients, group B), or TECNIS ZMA00 (Abbott Medical Optics, Santa Ana, CA) (22 patients, group C) MIOL. Intervention Phacoemulsification. Main Outc…
Visual and Refractive Outcomes in Hyperopic Pseudophakic Patients Implanted with the Acri.LISA 366D Multifocal Intraocular Lens
2009
Our purpose was to assess the visual quality after bilateral implantation of the Acri.LISA 366D intraocular lens (IOL; Carl Zeiss Meditec, Jena, Germany) in patients with hyperopia. We did a prospective and nonrandomized study. One hundred and seventy eyes of 85 patients had bilateral implantation of the Acri.LISA 366D IOL. The patients were divided into 2 groups: low to moderate hyperopia (IOL power, 21 to 24.5 diopters [D]) and high hyperopia (IOL power, 25 to 36 D). Monocular and binocular best spectacle-corrected visual acuity (BSCVA), best distance-corrected near visual acuity (BCNVA), binocular best distance-corrected intermediate visual acuity (VA), and distance contrast sensitivity …
Visual function comparison of 2 aspheric multifocal intraocular lenses
2011
To compare visual function after bilateral implantation of the multifocal Lentis Mplus LS-312 with a nonrotational symmetrical design (copolymer aspheric) or the Acrysof Restor SN6AD1 +3.0 D (hybrid aspheric) intraocular lens (IOL).Fernández-Vega Ophthalmological Institute, Oviedo, Spain.Comparative case series.Six months postoperatively, corrected distance visual acuity (CDVA), distance-corrected near visual acuity (DCNVA), the defocus curve, and photopic and mesopic contrast sensitivity with and without glare were measured.The mean CDVA was 0.02 ± 0.06 (SD) with the copolymer aspheric IOL and -0.06 ± 0.05 logMAR with the hybrid aspheric IOL (P=.07) and the mean DCNVA, 0.10 ± 0.06 and -0.0…
Stereoacuity with balanced presbyopic contact lenses.
2010
Our aim was to evaluate near stereoacuity with the balanced Proclear Multifocal simultaneous vision contact lens. Twenty-five presbyopic subjects were fitted binocularly with the Proclear Multifocal contact lens and with distance contact lenses combined with reading spectacles, which served as controls. After one month, stereoacuity was measured using the vectographic Titmus and Random dot stereotests and the Howard-Dolman (HD) apparatus under photopic conditions (85 cd/m(2) ) at 40 cm. Binocular high-contrast visual acuities (BHCVA) at distance and near were examined. For the multifocal group, mean stereoacuity with the Howard-Dolman method was 22.40 ± 8.23 seconds of arc. Using the Titmus…
Contrast sensitivity loss in the peripheral visual field following laser in situ keratomileusis.
2007
We report a case of contrast sensitivity loss in the peripheral visual field following laser in situ keratomileusis (LASIK). A 50-year-old white man was referred to us for differences in visual perception in the peripheral field between the right eye, which had had LASIK, and the left eye, which was emmetropic. Linear meridional static perimetry was carried out in the 0- to 180-degree meridian using a Goldmann perimeter to assess the peripheral perimetric thresholds. There was a statistically significantly marked increased threshold in contrast sensitivity in the nasal and temporal fields from 40 degrees of eccentricity in the LASIK eye compared with that in the emmetropic eye. Eyes treated…
Visual performance comparison between contact lens-based pinhole and simultaneous vision contact lenses.
2011
Background The aim was to evaluate the visual performance provided with a contact lens-based pinhole design against a simultaneous vision multifocal contact lens. Methods In a cross-over study at the University of Valencia, 22 presbyopic patients were evaluated using an artificial pupil fitted on the non-dominant eye and the simultaneous vision PureVision Multifocal contact lenses. After one month of contact lens wear, binocular distance visual acuity (BDVA), binocular near visual acuity (BNVA), defocus curve, binocular distance contrast sensitivity, binocular near contrast sensitivity, and stereoacuity were measured, under photopic conditions (85 cd/m2). In addition, binocular distance vis…
Artificial pupil versus contralateral balanced contact lens fit for presbyopia correction.
2014
Purpose: To assess and compare the effects of contact lens-based artificial pupil design and contralateral balanced multifocal contact lens combination (CBMCLC) on visual performance. Methods: This randomized crossover study conducted at the University of Valencia, Spain included 38 presbyopic patients using an artificial pupil contact lens in the nondominant eye and a CBMCLC. After a month of lens wear, the binocular distance visual acuity (BDVA), binocular near visual acuity (BNVA), defocus curve, binocular distance, and near contrast sensitivity and near stereoacuity (NSA) were measured under photopic conditions (85 cd/m2). Moreover, BDVA and binocular distance contrast sensitivity were …