نتایج جستجو برای: coma aberration
تعداد نتایج: 16755 فیلتر نتایج به سال:
PURPOSE To compare visual acuity, total and high order wavefront aberrations (coma, spherical aberration, and other terms of high order aberration), and contrast sensitivity in 105 eyes implanted with 4 different types of intraocular lenses (IOLs) (1 multifocal apodized diffractive IOL and 3 monofocal IOLs). METHODS A prospective study comparing four types of IOLs (Alcon ReSTOR [50 eyes], Alc...
Light traveling through any optical media other than a vacuum is distorted by the media. We call this distortion aberration. Aberration occurs for many reasons, including nonuniform indexes of refraction in the media, differential bending of light by “lenses” in the media, interface changes in the media, and scatter. This produces defocus, astigmatism, coma, spherical, and other types of wavefo...
We compared experimental wave aberrations in pseudophakic eyes with aspheric intraocular lenses (IOLs) to simulate aberrations from numerical ray tracing on customized computer eye models using corneal topography, angle lambda, ocular biometry, IOL geometry, and IOL tilt and decentration measured on the same eyes. We found high correlations between real and simulated aberrations even for the ey...
We explored the relative changes in ocular, corneal, and internal aberrations associated with normal aging with special emphasis in the role of ocular alignment and lens shape factor in the balance of aberrations. Ocular and corneal aberrations together with the angle kappa were measured for a 5-mm pupil diameter in 46 eyes with low refractive errors and ages ranging between 20 and 77 years. Th...
Residual aberrations in projection printing lenses result in spillover of electric field signals from a mask opening onto the surrounding region. This spillover results in a sidelobe displaced from the feature by 0.75λ/NA. This sidelobe is similar to that of an unwanted extra beam of an antenna. For attenuated phase-shifting masks, the interaction of this sidelobe with the background transmissi...
PURPOSE To investigate the effect of orthokeratology on peripheral aberrations in two myopic volunteers. METHODS The subjects wore reverse geometry orthokeratology lenses overnight and were monitored for 2 weeks of wear. They underwent corneal topography, peripheral refraction (out to +/-34 degrees along the horizontal visual field) and peripheral aberration measurements across the 42 degrees...
PURPOSE To report 18-month follow-up after transepithelial cross-linking (CXL) in young patients. METHODS Thirteen eyes with keratoconus were evaluated (mean patient age: 14.4 ± 3.7 years [range: 8 to 18 years]). Corrected distance visual acuity (CDVA); spherical equivalent refraction; keratometry (K); coma, spherical aberration, and higher order aberrations (HOAs) for a 5.0-mm pupil; and thi...
PURPOSE To characterize posterior corneal aberrations in keratoconic (KC) eyes and investigate compensatory effects between anterior and posterior corneal surfaces. METHODS The corneal topography of 113 eyes (37 advanced KC, 31 moderate KC, 14 mild KC, and 31 normal eyes) was used to compute the corneal aberrations. The central 6-mm diameter of both anterior and posterior corneal topographies...
Aim: To compare the changes in anterior corneal surface aberration characteristics after small-incision lenticule extraction (SMILE) versus Q-value-guided femtosecond laser-assisted in situ keratomileusis (Q-FS-LASIK) Methods: In this prospective comparative study, 102 patients with myopia and myopic astigmatism were divided between the SMILE and Q-FS-LASIK groups, consisting of 51 patients eac...
Acute Effect of Cigarette Smoking on Pupil Size and Ocular Aberrations: A Pre- and Postsmoking Study
Aim. To evaluate the acute effects of cigarette smoking on photopic and mesopic pupil sizes and wavefront aberrations. Methods. Cigarette smoker volunteers were recruited in the study. Photopic and mesopic pupil sizes and total ocular aberrations were measured before smoking and immediately after smoking. All volunteers were asked to smoke a single cigarette containing 1.0 mg nicotine. Pupil si...
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