PURPOSE To investigate corneal spherical aberration and corneal asphericity after small incision lenticule extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK). METHODS This study enrolled 70 patients having SMILE and 64 subjects receiving FS-LASIK. The preoperative spherical equivalent (SE) was -5.83 ± 1.23 diopters (D) and -6.20 ± 1.52 D, respectively. T...

PURPOSE To evaluate the visual outcomes and fourth-order Zernike spherical aberrations induced with a customized change in corneal asphericity (ΔQ) correction of presbyopia combined with monovision for hyperopic patients. METHODS Consecutive hyperopic patients who underwent presbyopic LASIK between September 2013 and July 2014 were included. For the non-dominant eyes, the aspheric ablation pr...

PURPOSE To evaluate changes induced by standard laser in situ keratomileusis (LASIK) for hyperopia on total and corneal optical quality. METHODS Total and corneal aberrations were measured before and after standard hyperopic LASIK in 13 eyes (preoperative spherical equivalent refractive error +3.17 +/- 1.10 D). The Chiron Technolas 217C laser with PlanoScan was used. Total aberrations (measur...

This paper concerns the slow viscous flow through a swarm of concentric clusters of porous spherical particles. An aggregate of clusters of porous spherical particles is considered as a hydro-dynamically equivalent to a porous spherical shell enclosing a solid spherical core. The Brinkman equation inside and the Stokes equation outside the porous spherical shell in their stream function formula...

This Letter reports experiments on the shape and path of air bubbles ~diameter range 0.1–0.2 cm! rising in clean water. We find that bubbles in this diameter range have two steady shapes, a sphere and an ellipsoid, depending on the size of the capillary tube from which they detach. The spherical bubbles move significantly slower than the ellipsoidal ones of equivalent volume. Bubbles with diame...

Three types of manifolds, spherical, fiat, and hyperbolic, are paradigms of geometric behavior. These are the Riemannian manifolds of constant positive, zero, and negative sectional curvatures, respectively. (The positive and negative sectional curvatures may be assumed, after scaling, to be + 1 and -1.) There is an equivalent synthetic geometric definition of them in terms of coordinate charts...

Obviously, toric lenses have to remain in stable positions after implantation bearing in mind that for every 10 degrees of misalignment, there is one third loss of toric correction. While some time ago this was still a problem, toric IOLs of today are significantly less affected by lens rotation. Another disturbing issue with toric lenses has also been fixed in the meantime: according to a new ...