منابع مشابه
CataraCt Surgery aStigmatiC CorreCtion
By Eric D. DonnEnfElD, MD Astigmatic management is the step that most often keeps patients from achieving optimal visual quality after refractive cataract surgery. Residual astigmatism of 0.50 D and sometimes less may result in glare, symptomatic blur, ghosting, and halos. A recent study of 4,540 eyes of 2,415 patients showed that corneal astigmatism was present in the majority of patients unde...
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Adapting to blurred or sharpened images alters the perceived focus of subsequently viewed images. We examined whether these adaptation effects could arise from actual sphero-cylindrical refractive errors, by testing aftereffects in images simulating second-order astigmatism. Image blur was varied from negative (vertical) through isotropic to positive (horizontal) astigmatism while maintaining c...
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T he treatment of moderate to high astigmatism is challenging for the refractive surgeon. Even in experienced hands, 40% of patients who undergo penetrating keratoplasty (PKP) are left with more than 4.00 D of astigmatism.1 Spectacles, contact lenses, excimer laser ablation, toric IOLs, and tissue-relaxing procedures have been used for a long time in the treatment of preexisting and postsurgica...
متن کاملSegment aberration effects on contrast.
High-contrast imaging, particularly the direct detection of extrasolar planets, is a major science driver for the next generation of telescopes. This science requires the suppression of scattered starlight at extremely high levels and that telescopes be correctly designed today to meet these stringent requirements in the future. The challenge increases in systems with complicated aperture geome...
متن کاملAmblyopia in astigmatic preschool children
Best-corrected acuity was measured for vertical and horizontal gratings and for recognition acuity optotypes (Lea Symbols) in a group of three- to five-year-old children with a high prevalence of astigmatism. Results showed meridional amblyopia (MA) among children with simple/compound myopic or mixed astigmatism, due to reduced acuity for horizontal gratings. Children with simple/compound hyper...
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ژورنال
عنوان ژورنال: Proceedings of the Physical Society of London
سال: 1902
ISSN: 1478-7814
DOI: 10.1088/1478-7814/18/1/356