نتایج جستجو برای: coma aberration
تعداد نتایج: 16755 فیلتر نتایج به سال:
PURPOSE To compare changes of anterior corneal aberration (Pentacam) and ocular aberration (aberrometer, LADARWave) after laser refractive surgery. METHODS Sixty-six eyes underwent laser refractive surgery and were retrospectively reviewed. Anterior corneal aberration and ocular aberration were measured by Pentacam and an aberrometer (LADARWave) respectively. Changes of root mean square (RMS)...
purpose: to investigate the effects of surface ablation excimer surgery on higher-order aberrations and to assess the safety and efficacy of wavefront-guided surface ablation excimer surgery in patients with hyperopia and hyperopic astigmatism. methods: in this analytical & descriptive study, wavefront-guided surface ablation excimer surgery was performed in 58 eyes of 31 patients with hyperopi...
Higher order optical aberrations were measured in 273 cyclopleged Singaporean school children using a Bausch and Lomb Zywave aberrometer, with 268 of these subjects also undergoing corneal topography measurements (Tomey TMS 2 system). Subjects with low myopia (> -3.00 to -0.50 D) showed slightly, but significantly, less positive levels of spherical aberration than other refractive error groups....
PURPOSE To determine pachymetric, aberrometric, and topometric indices in patients with definite and subclinical keratoconus and the validity of these indices in the diagnosis of keratoconus. METHODS We evaluated 262 keratoconic and 97 healthy eyes in this study. Pentacam HR examination was performed for all participants, and the data of all pachymetric, aberrometric, and topometric indices w...
We have extended the method of Alvarez [J. Am. Optom. Assoc. 49, 24 (1978)] to generate a variable magnitude of third-order spherical and/or coma aberration by using a combination of fourth-order plates with a magnification system. The technique, based on the crossed-cylinder aberroscope, is used to measure the wave-front aberration generated by the plates. The method has been applied to correc...
Misalignments always occur in real optical systems. These misalignments do not generate new aberration forms, but they change the aberration field dependence. Two-mirror telescopes have been used in several applications. We analyze a two-mirror telescope configuration that has negligible sensitivity to decenter misalignments. By applying the wave aberration theory for plane-symmetric optical sy...
AIM To compare higher order aberrations in two aspherical intraocular lenses (IOLs): Akreos advanced optics (AO) and Dr. Schmidt Microcrystalline 6125 aspheric anterior surface (MC6125AS) with each other. METHODS Forty eyes of 39 patients underwent phacoemulsification and Akreos AO and MC6125AS were implanted in their eyes in a random manner. Three months post-operatively, higher order aberra...
Further development of the objective version of the Howland and Howland [(1976) Science, 193, 580-582; (1977) Journal of the Optical Society of America, 67, 1508-1518] aberroscope technique for measuring ocular aberrations is described. Compensation for refractive corrections and calibration is discussed. The technique was used to investigate the effect of accommodation upon the monochromatic a...
A simple algebraic algorithm is proposed as a computational tool for the thin-lens design of a triplet which consists of a singlet and a cemented doublet. The triplet is required to yield specified amounts of lens power, primary spherical aberration, central coma, longitudinal chromatic aberration and secondary spectrum. The three element powers of the triplet are first obtained by solving the ...
VIII. IX. X. XI. XII. Sign Conventions Aberration-Free Image Spherical Wavefront, Defocus, and Lateral Shift Angular, Transverse, and Longitudinal Aberration Seidel Aberrations A. Spherical Aberration B. Coma C. Astigmatism D. Field Curvature E. Distortion Zernike Polynomials Relationship between Zernike Polynomials and Third-Order Aberrations Peak-to-Valley and RMS Wavefront Aberration Strehl ...
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